Post-halloween doc updates.

Post-halloween doc updates.

[Dave Jones]

I couldn't resist the irony of posting a post-halloween document
just before halloween. Quite a few changes since last posting here,
and with each posting I tend to get a lot of useful feedback for
the next round of changes.

		Dave



                     The post-halloween document. v0.46
                        (aka, 2.6 - what to expect)

                    Dave Jones <davej@codemonkey.org.uk>

                          (Updated as of 2.6.0test9)

This document explains some of the new functionality to be found in the 2.6
Linux kernel, some pitfalls you may encounter, and also points out some new
features which could really use testing.
Note, that "contact foo@bar.com" below also implies that you should also
cc: linux-kernel@vger.kernel.org.

Latest version of this document can always be found at
http://www.codemonkey.org.uk/docs/post-halloween-2.6.txt

Thanks to many [far too many to list] people for valuable feedback.

Note, that this document is somewhat x86-centric, but most features
documented here affect all platforms anyway.

Translations:
Spanish - http://www.terra.es/personal/diegocg/post-halloween-2.6.es.txt
German  - http://www.kubieziel.de/computer/halloween-german.html
Polish  - http://soltysiak.com/linux/post-halloween-2.6.pl.txt
pt_BR - www.maluco.com.br/thiago/docs/post-halloween-2.6-pt_BR.txt


Applying patches.
~~~~~~~~~~~~~~~~~
- In 2.4 and previous kernels, the recommended way to apply patches was
  to use a command line such as ...
  gzip -cd patchXX.gz | patch -p0
  In 2.6, Linus started adding an extra path element to the diffs,
  so using -p1 in the untarred 'to be patched' directory is necessary.


Known gotchas.
~~~~~~~~~~~~~~
Certain known bugs are being reported over and over. Here are the
workarounds.
- Blank screen after decompressing kernel?
  Make sure your .config has
   CONFIG_INPUT=y
   CONFIG_VT=y
   CONFIG_VGA_CONSOLE=y
   CONFIG_VT_CONSOLE=y
  A lot of people have discovered that taking their .config from 2.4 and
  running make oldconfig to pick up new options leads to problems, notably
  with CONFIG_VT not being set.
- An additional bug biting some people is that NICs fail to receive packets
  (usually notable by a NIC not getting a DHCP lease for eg, despite being
   sent one by the server). Booting with "noapic" "acpi=off" or a combination
  of both fixes this for most people. Additional breakage reports should go
  to Jeff Garzik <jgarzik@pobox.com>
- (Possibly linked to above bug) VIA APIC routing is currently broken.
  boot with 'noapic'.
- Can't load any modules? You need updated tools (See modules section below).


Regressions.
~~~~~~~~~~~~
(Things not expected to work just yet)
- The hptraid/promise drivers for proprietary RAID formats are currently
  non functional, and will probably be converted to use device-mapper.
- Some filesystems still need work (Intermezzo, UFS, HFS, HPFS..)
- A number of drivers don't compile currently due to them needing various
  work to convert them to the new APIs
- UMSDOS fs is currently missing, pending rewrite.
- The format of /proc/stat changed, which could break some
  applications that still depend on the old layout.
  Currently the only known application to break is the java 
  'DOTS' app. (http://bugme.osdl.org/show_bug.cgi?id=277)
- Some people seem to have trouble running rpm, most notably Red Hat 9 users.
  This is a known bug of rpm.
  Workaround: run "export LD_ASSUME_KERNEL=2.2.5", before running rpm.
  This is thought to be a bug related to db4 and O_DIRECT interaction.


Stuff needing forward porting from 2.4.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- HFSPlus
- SuperH 64


Removed features.
~~~~~~~~~~~~~~~~~
- khttpd is gone.
- Older Direct Rendering Manager (DRM) support (For XFree86 4.0)
  has been removed. Upgrade to XFree86 4.1.0 or higher.
- LVM1 has been removed. See Device-mapper below.
- The system call table is no longer exported. Any module that relied
  on this previously will no longer work.
- Soundmodem hamradio support has been removed. Its functionality
  has been superceded by a userspace replacement.
  http://www.baycom.org/~tom/ham/soundmodem
- Direct booting from floppy is no longer supported.
  You should now use a boot loader program instead.
- Callout tty devices (/dev/cua) have been deprecated since 2.1.90pre2.
  Support is now removed.


Deprecated/obsolete features.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- devfs has been obsoleted in favour of udev (http://www.kernel.org/pub/linux/utils/kernel/hotplug/)
- boot time root= parsing changed.
  ramdisks are now ram<n> instead of rd<n> and cm206 is cm206cd (instead of
  cm206).
- usbdevfs will be going away in 2.7. The same filesystem can
  be mounted as 'usbfs' in recent 2.4 kernels, and in 2.5.52
  and above, which is what the filesystem will furthermore be
  known as.
- elvtune is deprecated (as are the ioctl's it used).
  Instead, the io scheduler tunables are exported in sysfs (see below)
  in the /sys/block/<device>/queue/iosched directory.
  Jens wrote a document explaining the tunables of the new scheduler at
  http://www.lib.uaa.alaska.edu/linux-kernel/archive/2002-Week-44/att-deadline-iosched.txt
- Calling syscalls by numeric values is deprecated, and will go away
  in the next development series.


Modules.
~~~~~~~~
- The in-kernel module loader got reimplemented.
- You need replacement module utilities from
  http://www.kernel.org/pub/linux/kernel/people/rusty/modules/
- A backwards compatible set of module utilities is also available
  from the same URL in RPM format.
- Debian sid or Conectiva snapshot users can just use
  'apt-get install module-init-tools'
- Modules now free stuff marked with __init or __initdata.
- For Red Hat users, there's another pitfall in "/etc/rc.sysinit".
  During startup, the script sets up the binary used to dynamically load
  modules stored at "/proc/sys/kernel/modprobe". The initscript looks
  for "/proc/ksyms", but since it doesn't exist in 2.6 kernels, the
  binary used is "/sbin/true" instead.

  This, eventually, will keep modules from working. Red Hat users will
  have to patch the "/etc/rc.sysinit" script to set
  "/proc/sys/kernel/modprobe" to "/sbin/modprobe", even
  when "/proc/ksyms" doesn't exist.
- Modules now have a .ko suffix instead of .o


Kernel build system.
~~~~~~~~~~~~~~~~~~~~
- The build system is much improved compared to 2.4.
  You should notice quicker builds, and less spontaneous rebuilds
  of files on subsequent builds from already built trees.
- There are new graphical config tools.
  "make xconfig" now requires the qt libraries.
  "make gconfig" uses gtk libraries.
- Make menuconfig/oldconfig has no user-visible changes other than speed,
  whilst numerous improvements have been made.
- Several new debug targets exist: 'allyesconfig' 'allnoconfig' 'allmodconfig'.
- Note: The new configuration system is not CML2 related.
- Also note: Whilst some ideas were taken from it, Keith Owens'
  kbuild-2.5 project was not integrated.
- "make" is now the preferred command, without a target; it does <arch-zimage>
  and modules.
- "make -jN" is now the preferred parallel-make execution.
  Do not bother to provide "MAKE=xxx"
- The build is now much less verbose.  If you want to see exactly what's
  going on, try "make V=1" or set KBUILD_VERBOSE=1 in your environment.
- 'make kernel/mm.o' will build the named file, provided a
  corresponding source exists. This also works for (non-composite)
  modules. (FIXME: broken for modules right now?)
- 'make kernel/' will compile all files in a subdirectory and below.
- There is no need to run 'make dep' at any stage.
- 'make help' provides a list of typical targets, including debugging targets.


IO subsystem.
~~~~~~~~~~~~~
- You should notice considerable throughput improvements over 2.4 due
  to much reworking of the block and the memory management layers.
- Report any regressions in this area to Jens Axboe <axboe@suse.de>
  and Andrew Morton <akpm@osdl.org>
- Two different IO elevators are available. The default is the
  anticipatory IO scheduler. You can select the deadline scheduler by
  booting with "elevator=deadline" on the kernel command line.
- For some workloads the anticipatory scheduler is around 10% slower
  than deadline. Most notably, database workloads which seek all over the
  disk performing reads and synchronous writes. Database folks will likely
  want to boot with elevator=deadline to get that last bit of performance back.
- Assorted changes throughout the block layer meant various block
  device drivers had a large scale cleanup whilst being updated to
  newer APIs.
- The size and alignment of O_DIRECT file IO requests now matches that
  of the device, not the filesystem.  Typically this means that you
  can perform O_DIRECT IO with 512-byte granularity rather than 4k.
  But if you rely upon this, your application will not work on 2.4 kernels
  and will not work on some devices.


block device size support.
~~~~~~~~~~~~~~~~~~~~~~~~~~
- Thanks to work done by Peter Chubb, block devices can now access up to
  16TB on 32-bit architectures, and up to 8EB on 64-bit architectures.
- To use the new BLKGETSZ64 ioctls, you'll need updated file-utils.
  (Currently only jfsutils 1.0.20 has this change, patches for other
   filesystems are still pending merging)
- The old 'struct statfs' is not able to describe large devices - the
  statfs() system call will now return -EOVERFLOW for such devices.
  A new system call called statfs64() with a new structure has been added
  to support large devices. It it unknown at time of writing how many
  userspace utilities have been converted to take advantage of this
  syscall when available.


POSIX ACLs & Extended attributes.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- Userspace tools available at http://acl.bestbits.at


VM Changes.
~~~~~~~~~~~
- Version zero swap partitions are no longer supported (everything is
  using v1 now anyway - rerun mkswap if in doubt).
  Linux 2.0.x requires v0 swap space, Linux v2.1.117 and later
  support v1.  mkswap(8) can format swap space in either format.
- The actual 'reverse mappings' part of Rik van Riel's rmap vm was merged.
  VM behaviour under certain loads should improve.
- VM misbehaviour should be reported to linux-mm@kvack.org
- The VM explicitly checks for sparse swapfiles, and aborts if one is found.
- /proc/sys/vm/swappiness defines the kernel's preference for pagecache over
  mapped memory. Setting it to 100 (percent) makes it treat both types of
  memory equally. Setting it to zero makes the kernel very much prefer to
  reclaim plain pagecache rather than mapped-into-pagetables memory.
- The bdflush() syscall is now officially deprecated. The syscall
  does nothing, and prints a stern warning to users. The functionality
  is replaced by the pdflush daemons.
- Due to various changes, swap files should be just as fast as swap partitions.
- In 2.4, up to 64 swap files were possible. In 2.6, this number is reduced
  to 32.  Like 2.4, these files can be up to 64GB in size, though you will
  need a recent util-linux to have a mkswap utility that supports >2GB


Kernel preemption.
~~~~~~~~~~~~~~~~~~
- The much talked about preemption patches made it into 2.6.
  With this included you should notice much lower latencies especially
  in demanding multimedia applications. 
- Note, there are still cases where preemption must be temporarily disabled
  where we do not. These areas occur in places where per-CPU data is used.
- If you get "xxx exited with preempt count=n" messages in syslog,
  don't panic, these are non fatal, but are somewhat unclean.
  (Something is taking a lock, and exiting without unlocking)
- If you DO notice high latency with kernel preemption enabled in
  a specific code path, please report that to Andrew Morton <akpm@osdl.org>
  and Robert Love <rml@tech9.net>.
  The report should be something like "the latency in my xyz application
  hits xxx ms when I do foo but is normally yyy" where foo is an action
  like "unlink a huge directory tree".


Process scheduler improvements.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- Another much talked about feature. Ingo Molnar reworked the process
  scheduler to use an O(1) algorithm.  In operation, you should notice
  no changes with low loads, and increased scalability with large numbers
  of processes, especially on large SMP systems.
- Scheduler is now Hyperthreading SMP aware and will disperse processes
  over physically different CPUs, instead of just over logical CPUs.
- Robert Love wrote various utilities for changing behaviour of the
  scheduler (binding processes to CPUs etc). You can find these tools at
  http://tech9.net/rml/schedutils
- The behavior of sched_yield() changed a lot.  A task that uses
  this system call should now expect to sleep for possibly a very
  long time.  Tasks that do not really desire to give up the
  processor for a while should probably not make heavy use of this
  function.  Unfortunately, some GUI programs (like Open Office)
  do make excessive use of this call and under load their
  performance is poor.  It seems this new 2.6 behavior is optimal
  but some user-space applications may need fixing.
- The above applies to use of yield() in the kernel, too.
- 2.6 adds system calls for manipulating a task's processor
  affinity: sched_getaffinity() and sched_setaffinity()
- Regressions to mingo@redhat.com and rml@tech9.net
- Debian users who encounter effects such as skips in mp3
  playback, jerky mouse movement may want to stop the
  X server from renicing itself to -10
  You can alter this permanently with 'dpkg-reconfigure xserver-common';
  if you elect not to have /etc/X11/Xwrapper.config managed by debconf,
  simply edit it directly.
- Balancing of IRQs between multiple CPUs should be handled using the
  irqbalance (http://people.redhat.com/arjanv/irqbalance/) program.
- David Mosberger maintains a webpage containing some current 'known gotchas'
  of the O(1) scheduler at http://www.hpl.hp.com/research/linux/kernel/o1.php


PCI.
~~~~
- PCI domain support has been added.  For most people, this just means that
  all PCI slot names are extended with "0000:" on the front, but for people
  with bigger servers it means they're able to access all their PCI devices.
- More hotplug drivers have been added, including a fake PCI hotplug driver
  so people without specialised hardware can test hotplug features.

Random.
~~~~~~~
- /dev/hwrandom got support for some new hardware (now also backported to 2.4)
  such as the HW RNG on newer VIA Cyrix CPUs.
- rng-tools can be found at http://sourceforge.net/projects/gkernel


Fast userspace mutexes (Futexes).
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- Rusty Russell added functionality that allows userspace to have
  fast mutexes that only use syscalls when there is contention. Used by
  NPTL.
- Bert Hubert has written some documentation on this functionality
  at http://ds9a.nl/futex-manpages


epoll
~~~~~
Davide Libenzi wrote an event based poll replacement that got
included in 2.6.  More info available at
http://www.xmailserver.org/linux-patches/nio-improve.html
http://lwn.net/Articles/13587/


Threading improvements.
~~~~~~~~~~~~~~~~~~~~~~~
- Ingo Molnar put a lot of work into threading improvements for 2.6.
  Some of the features of this work are:
  -  Generic pid allocator (arbitrary number of PIDs with no slowdown,
     unified pidhash).
  -  Thread Local Storage syscalls
  -  sys_clone() enhancements (CLONE_SETTLS, CLONE_PARENT_SETTID, CLONE_SETTID,
     CLONE_CLEARTID, CLONE_DETACHED)
  -  POSIX thread signals stuff (atomic signals, shared signals, etc.)
  -  Per-CPU GDT
  -  Threaded coredumping support
  -  sys_exit() speedups (O(1) exit)
  -  Generic, improved futexes, vcache
  -  New, threading related ptrace features
  -  exit/fork task cache
  -  /proc updates for threading
  -  API changes for threading.
- Users should notice a significant speedup in basic thread operations.
  This is true to a lesser extent even for old-threading userspace libraries 
  such as LinuxThreads.
- Regressions should go to Ingo Molnar <mingo@redhat.com> and
  phil-list@redhat.com.  Regressions could happen in the area of signal
  handling and related threading semantics, plus coredumping.
- Native Posix Threading Library (NPTL).
  Ulrich Drepper worked closely with Ingo on the threading enhancements, and
  developed a 1:1 model threading library. You can find out more about NPTL at
  http://people.redhat.com/drepper/nptl-design.pdf


Enhanced coredumping. 
~~~~~~~~~~~~~~~~~~~~~
- 2.6 offers you the ability to configure the way core files are
  named through a /proc/sys/kernel/core_pattern file.
  You can use various format identifiers in this name to affect
  how the core dump is named.

    %p - insert pid into filename
    %u - insert current uid into filename
    %g - insert current gid into filename
    %s - insert signal that caused the coredump into the filename
    %t - insert UNIX time that the coredump occurred into filename
    %h - insert hostname where the coredump happened into filename
    %e - insert coredumping executable name into filename

  You should ensure that the string does not exceed 64 bytes.
- Multithreaded processes can now dump core


Input layer.
~~~~~~~~~~~~
- Possibly the most visible change to the end user. If misconfigured,
  you'll find that your keyboard/mouse/other input device will no longer work.
  2.6 offers a much more flexible interface to devices such as keyboards.
- The downside is more confusing options.
  In the "Input device support" menu, be sure to enable at least the following.

                    --- Input I/O drivers
                    < > Serial i/o support
                    < >   i8042 PC Keyboard controller
                    [ ] Keyboards
                    [ ] Mice

  (Also choose the relevant keyboard/mouse from the list)

- If you find your keyboard/mouse still don't work, edit the file
  drivers/input/serio/i8042.c, and replace the #undef DEBUG
  with a #define DEBUG

  When you boot, you should now see a lot more debugging information.
  Forward this information to Vojtech Pavlik <vojtech@suse.cz>

- If you use a KVM switcher, and experience problems, booting with the boot
  time argument 'psmouse_noext' should fix your problems.
- Users of multimedia keys without X will see changes in how the kernel
  handles those keys. People who customize keymaps or keycodes in 2.4
  may need to make some changes in 2.6
- Users wanting support for the PC speaker need to enable CONFIG_INPUT_PCSPKR,
  or you won't get a single beep.
- Synaptics touchpad users may be interested to check out
  http://w1.894.telia.com/~u89404340/touchpad/


PnP layer.
~~~~~~~~~~
- Support for plug and play devices such as early ISAPnP cards has improved a
  lot in the 2.6 kernel. The new code behaves more closely to the code
  handling PCI devices (probe, remove etc callbacks), and also merges
  PnP BIOS access code.
- Report any regressions in plug & play functionality to
  Adam Belay <ambx1@neo.rr.com>


ALSA.
~~~~~
- The advanced linux sound architecture got merged into 2.6.
  This offers considerably improved functionality over the older OSS drivers,
  but requires new userspace tools.
- Several distros have shipped ALSA for some time, so you may already have the
  necessary tools. If not, you can find them at http://www.alsa-project.org/
- ALSA can emulate OSS interface using the snd_pcm_oss/snd_pcm_mixer
  modules, if your card produces nothing but silence, you may need to run
  alsamixer to unmute channels wich /dev/mixer doesn't see
- Note that the OSS drivers are also still functional, and still present.
  Many features/fixes that went into 2.4 are still not applied to these
  drivers, and it's still unclear if they will remain when 2.6 ships.
  The long term goal is to get everyone moved over to (the superior) ALSA.


AGP.
~~~~
- The agpgart driver got a long overdue cleanup which involved
  splitting it into an agpgart core, and per-chipset drivers.
  You may need to adjust your modules configuration to autoload
  the chipset drivers on loading the agpgart module.
- Generic AGP 3.0 support is now included.

DRI.
~~~~
- Direct rendering in 2.6 hasn't had much (if any?) testing on
  older versions of XFree86. Feedback on whether 4.1 works would
  be useful.


Faster system calls.
~~~~~~~~~~~~~~~~~~~~
- Systems that support the SYSENTER extension (Basically Intel Pentium-II
  and above, and AMD Athlons) now have a faster method of making the
  transition from userspace to kernelspace when a syscall is performed.
- Pentium Pro also has SYSENTER, but due to errata, is unusable.
- Without an updated glibc, this will not be noticable.
- VMWare 4 users may get crashes due to this.
  Zwane Mwaikambo wrote a patch for a "nosysenter" option which is worth
  googling for if there isn't a vmware update available.
- Regressions to torvalds@osdl.org and libc-alpha@redhat.com


procps.
~~~~~~~
- The 2.6 /proc filesystems changed some statistics, which confuse older
  versions of procps. Rik van Riel and Robert Love have been maintaining a
  version of procps during the development of 2.6 which tracks changes to
  /proc which you can find at http://tech9.net/rml/procps/
- Alternatively, the procps by Albert Cahalan now supports the altered formats
  since v3.0.5  -- http://procps.sf.net/
- The /proc/meminfo format changed slightly which also broke gtop in strange
  ways. Likely this also broke some of the KDE/GNOME panel applets.


Framebuffer layer.
~~~~~~~~~~~~~~~~~~
- James Simmons has reworked the framebuffer/console layer considerably for
  2.6. Support for some cards is still lagging a little, but it should be
  functionally no different than previous incarnations.
- boot time arguments may have changed depending on your driver.
  an example of the change is..
    append = "video=radeon:1024x768-24@100"
  needs to become..
    append = "video=radeonfb:1024x768-24@100"
- Current userspace tools (fbset for eg) are not yet updated,
  and won't function as expected.
- The VESA framebuffer now enables MTRRs for the framebuffer memory range during
  initialisation (Note: PCI cards only).
  If you notice screen corruption, please report this, along with an lspci output,
  so your card can be blacklisted.
- Any problems should go to <jsimmons@infradead.org>


IDE.
~~~~
- The IDE code rewrite was subject to much criticism in early 2.5.x, which
  put off a lot of people from testing. This work was then subsequently
  dropped, and reverted back to a 2.4.18 IDE status.
  Since then additional work has occurred, but not to the extent
  of the first cleanup attempts.
- Known problems with the current IDE code. 
  o  Simplex IDE devices (eg Ali15x3) are missing DMA sometimes
  o  Most PCMCIA devices have unload races and may oops on eject
  o  Modular IDE does not yet work, modular IDE PCI modules sometimes
     oops on loading
  o  ide_scsi is completely broken in 2.6 currently. Known problem.
     If you need it either use 2.4 or fix it 8)
- IDE disk geometry translators like OnTrack, EZ Partition, Disk Manager
  are no longer autodetected. The only way forward is to remove the translator
  from the drive, and start over, or use boot parameters depending on the
  type of remapper used :-
    hdx=remap63   - add 63 to each sector (For OnTrack DM)
    hdx=remap     - remap 0->1 (For EZDrive)


IDE TCQ.
~~~~~~~~
- Tagged command queueing for IDE devices has been included.
- Not all combinations of controllers & devices may like this,
  so handle with care.
  READ AS: ** Don't use IDE TCQ on any data you value.
  It's likely bad combinations will be blacklisted as and when discovered.

- If you didn't choose the "TCQ on by default" option, you can enable
  it by using the command

    echo "using_tcq:32" > /proc/ide/hdX/settings

  (replacing 32 with 0 disables TCQ again).

- Report success/failure stories to Jens Axboe <axboe@suse.de> with
  inclusion of hdparm -i /dev/hdX, and lspci output.


SCSI.
~~~~~
- Various SCSI drivers still need work, and don't even compile.
- Various drivers currently lack error handling.
  These drivers will cause warnings during compilation due to
  missing abort: & reset: functions.
- Note, that some drivers have had these members removed, but still
  lack error handling. Those noticed so far are ncr53c8xxx, sym53c8xx
- large dev_t support allowing thousands of disks to be
  supported (was 128 or 256 in the 2.4 series)
- major code cleanup, initially to support the block layer (bio)
  improvements have led to:
   - better throughput (?) [less double handling of data]
   - per HBA locks (there was a single io_request_lock in
     the 2.4 series)
   - more flexible interface to HBA drivers
   - better hotplug support, especially for USB mass storage
     and ieee1394 sbp2 devices [well it's work_in_progress]
- improved error processing and scanning code (support for
  large, sparse lun spaces)
- lots of scsi driver internals available via sysfs


v4l2.
~~~~~
- The video4linux API finally got its long awaited cleanup.
- xawtv, bttv and most other existing v4l tools are also compatible
  with the new v4l2 layer. You should notice no loss in functionality.
- See http://bytesex.org/v4l/ for more information.


Quota reworking.
~~~~~~~~~~~~~~~~
The new quota system needs new tools. Supports 32 bit uids.
http://www.sf.net/projects/linuxquota/


CD Recording.
~~~~~~~~~~~~~
- Jens Axboe added the ability to use DMA for writing CDs on
  ATAPI devices. Writing CDs should be much faster than it
  was in 2.4, and also less prone to buffer underruns and the like.
- With a recent cdrecord, you also no longer need ide-scsi in order to use
  an IDE CD writer.
- Ripping audio tracks off of CDs now also uses DMA and should be
  notably faster. You can also find an updated cdda2wav at:
  *.kernel.org/pub/linux/kernel/people/axboe/tools/
- Send good/bad reports of audio extraction with cdda2wav and burning with
  the cdrecord to Jens Axboe <axboe@suse.de>
- Currently only 'open by device name' works in cdrecord.
  cdrecord -dev=/dev/hdX -inq
- More info at http://lwn.net/Articles/13538/ & http://lwn.net/Articles/13160/


USB:
~~~~
- USB host controller drivers got renamed in 2.6. They are now
   uhci-hcd for UHCI controllers.
   ohci-hcd for OHCI controllers.
   ehci-hcd for EHCI (USB 2.0) controllers.
- Very little user visible changes, the only noticable 'major' change
  is that there is now only one UHCI driver. As noted elsewhere, usbdevfs 
  got renamed to usbfs.
- USB-storage has changed behaviour. A device which is disconnected and
  then reconnected is not reassociated with the old /dev node.
- USB storage also got several performance enhancements.


Nanosecond stat:
~~~~~~~~~~~~~~~~
The stat64() syscall got changed to return jiffies granularity.
This allows make(1) to make better decisions on whether or not it
needs to recompile a file. Not all filesystems may support such precision.


Filesystems:
~~~~~~~~~~~~
A number of additional filesystems have made their way into 2.6.
Currently it supports: ext2, ext3, reiserfs, jfs, xfs, minix, romfs,
iso9660, udf, msdos, vfat, ntfs (ro), adfs, amiga ffs, apple macintosh hfs,
BeOS befs (ro), bfs, efs (ro), cramfs, free vxfs, os/2 hpfs, qnx4fs,
sysvfs, ufs.
Whilst these have had testing out of tree, the level of testing
after merging is unparalleled. Be wary of trusting data to immature
filesystems.  A number of new features and improvements have also
been made to the existing filesystems from 2.4.

Reports of stress testing with the various tools available would
be beneficial.


Generic VFS changes.
~~~~~~~~~~~~~~~~~~~~
- Since Linux 2.5.1 it is possible to atomically move a subtree to
  another place. The call is...
   mount --move olddir newdir
- Since 2.5.43, dmask=value sets the umask applied to directories only.
  The default is the umask of the current process.
  The fmask=value sets the umask applied to regular files only.
  Again, the default is the umask of the current process.
- Directories can now be marked as synchronous using chattr +S,
  so that all changes will be immediately written to disk.
  Note, this does not guarantee atomicity, at least not for all filesystems
  and for all operations.  You *can* be guaranteed that system calls will
  not return until the changes are on disk; note though that this does have
  has some significant performance impacts.



devfs.
~~~~~~
- devfs got somewhat stripped down and a lot of duplicate functionality
  got removed. You now need to enable CONFIG_DEVPTS_FS=y and mount
  the devpts filesystem in the same manner you would if you were not
  using devfs.


EXT2.
~~~~~
- 2.5.49 included an extension to ext2 which will cause it to not attach
  buffer_head structures to file or directory pagecache at all, ever.
  This is for the big highmem machines.  It is enabled via the `-o nobh'
  mount option.
- The ext2 filesystem is now using finer-grained locking which yields reduced
  context switch rates and higher throughput on large SMP machines.


EXT3.
~~~~~
- The ext3 filesystem has gained indexed directory support, which offers
  considerable performance gains when used on filesystems with directories
  containing large numbers of files.
- In order to use the htree feature, you need at least version 1.32 of
  e2fsprogs.
- Existing filesystems can be converted using the command

    tune2fs -O dir_index /dev/hdXXX

- The latest e2fsprogs can be found at
  http://prdownloads.sourceforge.net/e2fsprogs
- The ext2 and ext3 filesystems have new file allocations policies (the "Orlov
  allocator") which will place subdirectories closer together on-disk.  This
  tends to mean that operations which touch many files in a directory tree are
  much faster if that tree was created under a 2.6 kernel.

Reiserfs.
~~~~~~~~~
- Reiserfs now supports inode attributes such as immutable.
  (Also included in 2.4.17, so not really 'new').
- Relocated/non-standard size journal support (also backported
  to 2.4.22pre3)
- Support for writes larger than 4KB in size, which means speedups
  on large file writes, esp in append mode, should also be more
  SMP friendly.
- Variable blocksize support. (Ie, you can choose any blocksize
  in the range of 1024 .. PAGE_CACHE_SIZE, must be power of 2).


NFS.
~~~~
- Basic support has been added for NFSv4 (server and client)
- Additionally, kNFSD now supports transport over TCP.
  This experimental feature is also backported to 2.4.20
- Interoperability reports with other OS's would be useful.
- v1.0.3 of nfs-utils supports the newer 2.6 kernels change
  of kdev_t type. You can grab it at http://nfs.sourceforge.net
- Problems to nfs@lists.sourceforge.net


NTFS.
~~~~~
- A new, rewritten NTFS driver got merged for 2.6. It has the
  following main benefits over the old driver:
  - SMP and reentrant safe
  - support bigger than 4 kB cluster sizes
  - full support for sparse files on W2K/XP/W2K3
  - mmap() support
  - More stable, and much faster than the previous NTFS driver.
  - Still read-only, but with safe file overwrite support without changes
  to the file size
  - More information is available at http://linux-ntfs.sf.net


sysfs.
~~~~~~
In simple terms, the sysfs filesystem is a saner way for
drivers to export their innards than /proc.
This filesystem is always compiled in, and can be mounted
just like another virtual filesystem. No userspace tools
beyond cat and echo are needed.

    mount -t sysfs none /sys

See Documentation/filesystems/sysfs.txt for more info.


JFS.
~~~~
IBM's JFS got merged for 2.6. (And backported to 2.4.20, but
it was still a new feature here first. You can read more about JFS at
http://www-124.ibm.com/developerworks/oss/jfs/index.html


XFS.
~~~~
The SGI XFS filesystem has been merged, and has a number of userspace
features. Users are encouraged to read http://oss.sgi.com/projects/xfs
for more information.
The various utilities for creating and manipulating XFS volumes can
be found on SGI's ftp server:
ftp://oss.sgi.com/projects/xfs/download/download/cmd_tars/xfsprogs-2.5.4.src.tar.gz


CIFS.
~~~~~
Support utilities and documentation for the common internet file system (CIFS)
can be found at http://us1.samba.org/samba/Linux_CIFS_client.html


FAT.
~~~~
CVF (Compressed VFAT) support has been removed. This means you
will no longer be able to access DriveSpace partitions.


HugeTLBfs.
~~~~~~~~~~
Files in this filesystem are backed by large pages if the CPU
supports them. See Documentation/vm/hugetlbpage.txt for more details.


Internal filesystems.
~~~~~~~~~~~~~~~~~~~~~
/proc/filesystems will contain several filesystems that are not
mountable in userspace, but are used internally by the kernel
to keep track of things. Amongst these filesystems are futexfs 
and eventpollfs.


Kernel Asynchronous I/O (AIO) Support
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Support for kernel AIO has been included in 2.6. 

AIO enables even a single application thread to overlap I/O 
operations with other processing, by providing an interface
for submitting one or more i/o requests in one system call
(io_submit) without waiting for completion, and a separate 
interface (io_getevents) to reap completed i/o operations
associated with a given completion group.

The following is a quick summary of what works today as 
expected:
- AIO read and write on raw (and O_DIRECT on blockdev)
- AIO read and write on files opened with O_DIRECT on
  ext2, ext3, jfs, xfs

And what doesn't work as expected or is not currently 
supported:
- AIO read and write on files opened without O_DIRECT
  (i.e. normal buffered filesystem AIO). On ext2, ext3,
  jfs, xfs and nfs, these do not return an explicit
  error, but quietly default to synchronous or rather 
  non-AIO behaviour (i.e io_submit waits for i/o to complete 
  in these cases). For most other filesystems, -EINVAL is 
  reported.
- AIO fsync (not supported for any filesystem)
- AIO read and write on sockets (doesn't return an
  explicit error, but quietly defaults to synchronous
  or rather non-AIO behaviour)

You need to install libaio-0.3.92 (available at 
http://www.kernel.org/pub/linux/kernel/people/bcrl/aio/) 
if you are writing AIO applications which use the native 
AIO interfaces.

More info is available at http://lse.sf.net/io/aio.html


Profiling.
~~~~~~~~~~
- A system wide performance profiler (Oprofile) has been included in 2.6.
  With this option compiled in, you'll get an oprofilefs filesystem
  which you can mount, that the userspace utilities talk to.
  You can find out more at http://oprofile.sf.net/
- You need a fixed readprofile utility for 2.6.
  Present in util-linux as of 2.11z



Improved BIOS table support.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- Linux now supports various new BIOS extensions.


Simple boot flag support.
~~~~~~~~~~~~~~~~~~~~~~~~~
The SBF specification is an x86 BIOS extension that allows improved
system boot speeds. It does this by marking a CMOS field to say
"I booted okay, skip extensive POST next reboot".
Userspace tool is at http://www.codemonkey.org.uk/projects/sbf/sbf.c
More info on SBF is at http://www.microsoft.com/hwdev/resources/specs/simp_bios.asp


EDD Support.
~~~~~~~~~~~~
- Support for BIOS Enhanced Disk Drive Services (EDD) was added,
  which exports information on what the BIOS thinks is the boot
  drive and other useful info to /sys/firmware/edd
- Matt Domsch is interested in hearing success/fails on this code
  with some simple tests decribed at http://domsch.com/linux/edd30/results.html


Improved system monitoring.
~~~~~~~~~~~~~~~~~~~~~~~~~~~
- lm_sensors.
  - Shipped in vendors kernels for years, lm_sensors is now part of mainline.
    It does however have a different interface. (/sysfs instead of /proc
  - http://www.xs4all.nl/~thospel/ASIS/bin/psensors is a handy script
    for parsing the new sysfs fields.
- IPMI. (Intelligent Platform Management Interface)
  - IPMI is a standard for monitoring the hardware in a system.
  - Project home page: http://openipmi.sourceforge.net
  - Specification: http://www.intel.com/design/servers/ipmi/spec.htm


x86 CPU detection.
~~~~~~~~~~~~~~~~~~
- The CPU detection code got a pretty hefty shake up. To be certain your
  CPU has all relevant workarounds applied, be sure to check that it was
  detected correctly. cat /proc/cpuinfo will tell what the kernel thinks it is.
- Likewise, the x86 MTRR driver got a considerable makeover.
  Check that XFree86 sets up MTRRs in the same way it did in 2.4
  (Failures will get logged in /var/log/XFree86.log)
- Early PII Xeon processors and possibly other early PII processors
  require microcode updates either from the BIOS or the microcode driver
  to work around CPU bugs the O(1) scheduler exposes.
  You can find the relevant microcode tools at
  http://www.urbanmyth.org/microcode/
- Any regressions in both should go to mochel@osdl.org Cc: davej@codemonkey.org.uk


Extra tainting.
~~~~~~~~~~~~~~~
Running certain AMD processors in SMP boxes is out of spec, and will taint
the kernel with the 'S' flag.  Running 2 Athlon XPs for example may seem to
work fine, but may also introduce difficult to pin down bugs.
In time it's likely this tainting will be extended to cover other out of
spec cases.

Additionally, the new modules interface will taint the kernel if you try
to 'force' a module to load with insmod -f.


Power management.
~~~~~~~~~~~~~~~~~
- 2.6 contains a more up to date snapshot of the ACPI driver. Should
  you experience any problems booting, try booting with the argument
  "acpi=off" to rule out any ACPI interaction. ACPI has a much more involved
  role in bringing the system up in 2.6 than it did in 2.4
- The old "acpismp=force" boot option is now obsolete, and will be ignored
  due to the old "mini ACPI" parser being removed.
- software suspend is still in development, and in need of more work.
  Use with SMP and/or PREEMPT not advised.
- The ACPI code will do basic sanity checks on the DMI structure in the BIOS
  to determine the date it was written. BIOSes older than year 2000 are
  assumed to be broken. In some circumstances, this assumption is wrong.
  If you see a message saying ACPI is disabled for this reason, try booting
  with acpi=force. If things work fine, send the output of dmidecode
  (http://www.nongnu.org/dmidecode/) to acpi-devel@lists.sf.net
  with an explanation of why your BIOS shouldn't be blacklisted.

CPU frequency scaling.
~~~~~~~~~~~~~~~~~~~~~~
Certain processors have the facility to scale their voltage/clockspeed.
2.6 introduces an interface to this feature, see Documentation/cpufreq
for more information. This functionality also covers features like
Intel's speedstep, and the Powernow! feature present in mobile AMD Athlons.
In addition to x86 variants, this framework also supports various ARM CPUs.
You can find a userspace daemon that monitors battery life and
adjusts accordingly at: http://sourceforge.net/projects/cpufreqd


Background polling of MCE.
~~~~~~~~~~~~~~~~~~~~~~~~~~
The machine check handler has been extended so that it regularly polls
for any problems on AMD Athlon, and Intel Pentium 4 systems.
This may result in machine check exceptions occuring more frequently
than they did in 2.4 on out of spec systems (Overclocking/inadequate
cooling/underated PSU etc..).


LVM2 - DeviceMapper.
~~~~~~~~~~~~~~~~~~~~
The LVM1 code got removed wholesale, and replaced with a much better
designed 'device mapper'.
- This is backwards compatible with the LVM1 disk format.
- Device mapper does require new tools to manage volumes however.
  You can get these from ftp://ftp.sistina.com/pub/LVM2/tools/


Debugging options.
~~~~~~~~~~~~~~~~~~
During the stabilising period, it's likely that the debugging options
in the kernel hacking menu will trigger quite a few problems.
Please report any of these problems to linux-kernel@vger.kernel.org
rather than just disabling the relevant CONFIG_ options.

Merging of kksymoops means that the kernel will now spit out
automatically decoded oopses (no more feeding them to ksymoops).
For this reason, you should always enable the option in the
kernel hacking menu labelled "Load all symbols for debugging/kksymoops".

Testing with CONFIG_PREEMPT will also increase the amount of debug
code that gets enabled in the kernel. Kernel preemption gives us
the ability to do a whole slew of debugging checks like sleeping
with locks held, scheduling while atomic, exiting with locks held, etc.


Compiler issues.
~~~~~~~~~~~~~~~~
- The recommended compiler (for x86) is still 2.95.3.
- When compiled with a modern gcc (Ie gcc 3.x), 2.6 will use additional
  optimisations that 2.4 didn't. This may shake out compiler bugs that
  2.4 didn't expose.
- Do not use gcc 3.0.x on x86 due to a stack pointer handling bug.
- gcc 2.96 is not supported with CONFIG_FRAME_POINTER=y due to a stack
  pointer handling bug.


Security concerns.
~~~~~~~~~~~~~~~~~~
Several security issues solved in 2.4 may not yet be forward ported
to 2.6. For this reason 2.6.x kernels should not be tested on
untrusted systems.  Testing known 2.4 exploits and reporting results
is useful.

SELinux.
~~~~~~~~
NSA Security-Enhanced Linux (SELinux) got merged in 2.6.
It is disabled by default and can be enabled with a boot time parameter
selinux=1.
You can obtain SELinux tools and an example policy configuration from
http://www.nsa.gov/selinux

Networking.
~~~~~~~~~~~
- ebtables
  The bridging firewall code got merged. To manage these you'll
  need the ebtables tool available from
  http://users.pandora.be/bart.de.schuymer/ebtables/
  More on bridge-nf can be found at http://bridge.sourceforge.net
- Bridged packets can now be 'seen' by iptables.
- IPSec
  Linux finally has IPSec support in mainline.  Use the KAME tools port on
  http://sourceforge.net/projects/ipsec-tools
  For more info see http://www.lib.uaa.alaska.edu/linux-kernel/archive/2002-Week-44/1127.html
  Also Bert Hubert has a howto at http://lartc.org/howto/lartc.ipsec.html
  Additionally, ipsec-utils is at http://sourceforge.net/projects/ipsec-tools
  Herbert Xu also has patches against FreeSWAN 2.00 to allow its userspace
  to use the 2.6 IPSec functionality. They can be downloaded from
  http://gondor.apana.org.au/~herbert/freeswan/
  An additional HOWTO is at http://www.ipsec-howto.org
- Some applications may trigger the kernel to spit out warnings about
  'process xxx using obsolete setsockopt SO_BSDCOMPAT' .
  - Bind 9.2.2 checks for #ifdef SO_BSDCOMPAT in <asm/socket.h> correctly,
    so a recompile is all that is needed.
  - bind9-host from debian testing triggers, though the 'host' package doesn't.
  - process `snmpd' is using obsolete setsockopt SO_BSDCOMPAT
  - process `snmptrapd' is using obsolete setsockopt SO_BSDCOMPAT
  - ntop uses obsolete (PF_INET,SOCK_PACKET)
- Users of boxes with >1 NIC may find that for eg, eth0 and eth1 refer to
  the opposites of what they did in 2.4.   This is a bug that will be fixed
  before 2.6.0.  One option (or management workaround) for this is to use
  'nameif' to name Ethernet interfaces.  There is a HOWTO for doing this at
  <http://xenotime.net/linux/doc/network-interface-names.txt>
- Support for various new RFCs.
  - RFC3173 (IP Payload Compression).
  - RFC3041 (IPv6 Privacy Extensions).
  - RFC2473 (IPv6 in IPv6 tunnels).
  - RFC2960 (SCTP - see below).
- Linux reaches congestion collapse when subjected to heavy network load.
  NAPI fixes this amongst other things and therefore improving network
  performance.
  More info at http://www.cyberus.ca/~hadi/usenix-paper.tgz and
  ftp://robur.slu.se/pub/Linux/net-development/NAPI/
- IPVS (IP Virtual Server)
  http://www.linuxvirtualserver.org/
- SCTP (Stream Control Transport Protocol)
  SCTP is an IP based, message oriented reliable transport protocol with
  congestion control, support for transparent multi-homing and multiple
  ordered streams of messages. RFC2960 defines the core protocol.
  More information about the protocol can be found at
    http://www.ietf.org/rfc/rfc2960.txt
  and about the Linux kernel implementation at
    http://lksctp.sourceforge.net
- ANSI/IEEE 802.2 LLC type 2 Support
  Full implementation of LLC 1 and 2 stack, used by Appletalk, IPX and Token
  Ring, also needed for the out of the tree, not yet functional NetBEUI
  stack and for the for Linux SNA.
                                                                                
  This is based on the stack released under the GPL by Procom Inc. for the
  2.0.30 Linux kernel.


Crypto
~~~~~~
- A generic crypto API has been merged, offering support for various
  algorithms (HMAC,MD4,MD5,SHA-1,SHA256,SHA384,SHA512,DES,Triple DES EDE,
  Blowfish, Twofish, Serpent, AES, CAST5, CAST6)

- This functionality is used by IPSec and the crypto-loop.  It's possible
  that it will later also be available for use in userspace through a crypto
  device, possibly compatible with the OpenBSD crypto userspace.

- The in-kernel loopback device can now do crypto using the CryptoAPI.
  May need new userspace tools.


Ports.
~~~~~~
- 2.6 features support for several new architectures.
  - x86-64 (AMD Hammer)
  - ppc64
  - UML (User mode Linux)
    See http://user-mode-linux.sf.net for more information.
  - uCLinux: m68k(w/o MMU), h8300 and v850.  sh also added a uCLinux option.
- The 64 bit s390x port got collapsed into a single port, appearing
  as a config option in the base s390 arch.
- In the opposite direction, arm26 was split out from arm.
- x86 architecture also got 'subarch' support to support 'strange' x86
  boxes (usually big boy toys). Currently supported subarchs include
  - ES7000
  - PC9800 (incomplete merge)
  - VISWS (Was in 2.4, but now maintained again)
  - Voyager. (http://www.hansenpartnership.com/voyager/)


- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Revision history:
0.46 - Update akpm's email address.
       Mention LLC in the networking section.
       Added link to 2.6 migration guide.
0.45 - DEVFS is obsolete.
       Add pt_BR translation.
0.44 - lm_sensors.
       x86 subarch support.
       Add link to Joseph Pranevich's 2.6 doc.
       Mention chattr +S
       Update dmidecode URL
       Fix sbf.c URL
       Fix typos (s/proprietory/proprietary/)
       add URL to patched cdda2wav.
       Mention which filesystems does 2.6 actually supports.
       Add a small note about SELinux
       Add a few more RFCs which we now support in the Networking section
       Change IPVS to IPVS (IP Virtual Server)
       Mention additional encryption algorithms that crypto api supports
       Add a few things to TODO section
       Add URL to AIO.
       Polish translation URL added.
       Fix up a stray davej@suse.de that I missed.
	   Update spanish translation URL.
0.43 - oprofile URL changed.
       Update Linus' email       
       Drop report of buggy Red Hat 3.2.2-5 gcc.
       Remove reference to Jens' hacked cdrecord, standard version is now ok.
       PC Speaker note added.
       Mention elevator=deadline for database folks.
       Merge two deprecated sections.
       Update URL to xfsprogs.
       Mention Conectiva module-init-tools
       Mention acpi=force, and DMI blacklist.
       DRI CFT on X4.1
       Pentium Pro SYSENTER is broken.
       Update Alans list of IDE bugs
       Add geometry translator workarounds.
       Mention swapfile limitations.
       Update Reiserfs new features.
       Move some features marked as 'deprecated' to 'removed'.
       Add 'needs forward porting' section.
       Pointer to synaptics touchpad driver webpage.
       Update ipsec utils URL.
       Mention usb-storage changes.
       Modules are now .ko instead of .o
       Mention how to change elevator on command line.
       Document statfs64()
       ext3 data=journal mode should now be fixed.
       Fix iosched pathname.
       Document USB changes.
       Add SCTP to Networking.
       s/2.5/2.6/ in most of the doc.
       Mention AIO.
       Add additional IPSEC howto URL.
       Deprecate numeric sysctls
0.42 - CONFIG_LOG_BUF_SHIFT is now sanity checked by Kconfig
       Hyperthreading scheduler improvements.
       ALSA OSS emulation.
       32bit uids in new quota.
       Not all filesystems support nanosecond stat.
       Note that NTFS still isn't R/W
       Mention CryptoLoop.
0.41 - V=0 is now default. Document V=1
       s/Redhat/Red Hat/ everywhere.
       Added vmware sysenter note.
       MTRR for vesafb
       Various grammar fixes.
       Selectable elevators.
       PCI domains
0.40 - Callout tty devices are removed.
       Added note about modules in Red Hat 9
0.39 - irqbalance note added.
       Added ntop, snmp tools obsolete messages.
       Added link to David Mosberger's O(1) page.
       Mention Herbert Xu's FreeSWAN patches.
       Add CONFIG_VGA_CONSOLE to the list of gotchas.
       Add note about 2.4 .config's to gotchas.
       Reword devpts note.
0.38 - Fixed URL to nameif
0.37 - devfs users now need to mount devpts.
       mention h8300 port.    
       mentioned NTFS rewrite.
0.36 - Include Doug Gilberts 'positive SCSI spin'.
       Mention NAPI.
       Reword the CPU bug workaround that the O(1) scheduler exposes.
       Added 'Known Gotchas' section
0.35 - Note about KDE panel applets.
       mount --move, dmask, fmask
       Removed note about oprofile utilities being underdeveloped.
       Mention ext2 locking, and ext2/ext3 orlov allocator.
0.34 - Remove people.redhat.com NPTL URLs on Ulrich Dreppers request.
       Added note about s390x going away.
       Various kbuild updates.
       Note about swap files.
       Added note about -p1 vs -p0
       Lots of typo fixes from Randy Dunlap.
       RPM from RH9 seems to have problems.
0.33 - Networking RFCs section added.
0.32 - Added Soundmodem userspace replacement URL.
0.31 - ext3 data=journal breakage noted.
0.30 - Athlon powernow is now supported.
0.29 - Mention NIC renumbering and ACPI/APIC NIC bugs. 
0.28 - SO_BSDCOMPAT obsolete messages, nfsutils.
0.27 - radeon -> radeonfb
0.26 - Added info about readprofile.
0.25 - Added cdrecord example. Added URL to Spanish translation.
0.1->0.24 - Unrecorded history

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Other Links.
http://www.kernelnewbies.org/status/
http://bugzilla.kernel.org/
http://www.kniggit.net/wwol26.html
http://thomer.com/linux/migrate-to-2.6.html


TODO:  (Please mail me a few lines about these if you are
         the owner of these).

 PCI IDs (new_id, agpgart try_unsupported)
 gadgetfs
 libsysfs
 kdev_t changes?
 ISDN rewrite?
 AFS
 DVB
 Hangcheck timer
 /proc/sysrq-trigger
 libata

Re: Post-halloween doc updates.

[Jeff Garzik]

Dave Jones wrote:
> - An additional bug biting some people is that NICs fail to receive packets
>   (usually notable by a NIC not getting a DHCP lease for eg, despite being
>    sent one by the server). Booting with "noapic" "acpi=off" or a combination
>   of both fixes this for most people. Additional breakage reports should go
>   to Jeff Garzik <jgarzik@pobox.com>

As this is a symptom of irq routing failure, I dunno if bug reports 
should necessarily go to me :)



> Stuff needing forward porting from 2.4.
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> - HFSPlus

I think Roman Zippel updated this recently?


> - Direct booting from floppy is no longer supported.
>   You should now use a boot loader program instead.

hmmm, what does this mean?

"make bzdisk" continues to work...  it requires syslinux, however, so 
that the makefile may install the syslinux bootloader on the floppy.



> Modules.
> ~~~~~~~~
> - For Red Hat users, there's another pitfall in "/etc/rc.sysinit".
>   During startup, the script sets up the binary used to dynamically load
>   modules stored at "/proc/sys/kernel/modprobe". The initscript looks
>   for "/proc/ksyms", but since it doesn't exist in 2.6 kernels, the
>   binary used is "/sbin/true" instead.
> 
>   This, eventually, will keep modules from working. Red Hat users will
>   have to patch the "/etc/rc.sysinit" script to set
>   "/proc/sys/kernel/modprobe" to "/sbin/modprobe", even
>   when "/proc/ksyms" doesn't exist.

Is this all still true?

Bill Nottingham graciously updated modutils to support 2.6.x, and 
locally all my Red Hat systems (with the updated modutils) work out of 
the box.


> IDE.
> ~~~~
> - The IDE code rewrite was subject to much criticism in early 2.5.x, which
>   put off a lot of people from testing. This work was then subsequently
>   dropped, and reverted back to a 2.4.18 IDE status.
>   Since then additional work has occurred, but not to the extent
>   of the first cleanup attempts.
> - Known problems with the current IDE code. 
>   o  Simplex IDE devices (eg Ali15x3) are missing DMA sometimes

I think this is fixed now...  Bart?


>   o  Most PCMCIA devices have unload races and may oops on eject
>   o  Modular IDE does not yet work, modular IDE PCI modules sometimes
>      oops on loading
>   o  ide_scsi is completely broken in 2.6 currently. Known problem.
>      If you need it either use 2.4 or fix it 8)

also perhaps add a mention of new and spiffy Serial ATA drivers :)



> CD Recording.
> ~~~~~~~~~~~~~
> - Jens Axboe added the ability to use DMA for writing CDs on
>   ATAPI devices. Writing CDs should be much faster than it
>   was in 2.4, and also less prone to buffer underruns and the like.
> - With a recent cdrecord, you also no longer need ide-scsi in order to use
>   an IDE CD writer.

Maybe add a pointer in the IDE section, pointing to this section?  Since 
they both mention ide-scsi...



> Generic VFS changes.
> ~~~~~~~~~~~~~~~~~~~~
> - Directories can now be marked as synchronous using chattr +S,
>   so that all changes will be immediately written to disk.
>   Note, this does not guarantee atomicity, at least not for all filesystems
>   and for all operations.  You *can* be guaranteed that system calls will
>   not return until the changes are on disk; note though that this does have
>   has some significant performance impacts.

Also, too, this is filesystem-specific, right?


> devfs.
> ~~~~~~
> - devfs got somewhat stripped down and a lot of duplicate functionality
>   got removed. You now need to enable CONFIG_DEVPTS_FS=y and mount
>   the devpts filesystem in the same manner you would if you were not
>   using devfs.

Wasn't this mentioned elsewhere in the document?



> Improved BIOS table support.
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> - Linux now supports various new BIOS extensions.

This is a bit vague.  Even I have no idea what this refers to :)



> Power management.
> ~~~~~~~~~~~~~~~~~
> - 2.6 contains a more up to date snapshot of the ACPI driver. Should
>   you experience any problems booting, try booting with the argument
>   "acpi=off" to rule out any ACPI interaction. ACPI has a much more involved
>   role in bringing the system up in 2.6 than it did in 2.4
> - The old "acpismp=force" boot option is now obsolete, and will be ignored
>   due to the old "mini ACPI" parser being removed.
> - software suspend is still in development, and in need of more work.
>   Use with SMP and/or PREEMPT not advised.
> - The ACPI code will do basic sanity checks on the DMI structure in the BIOS
>   to determine the date it was written. BIOSes older than year 2000 are
>   assumed to be broken. In some circumstances, this assumption is wrong.
>   If you see a message saying ACPI is disabled for this reason, try booting
>   with acpi=force. If things work fine, send the output of dmidecode
>   (http://www.nongnu.org/dmidecode/) to acpi-devel@lists.sf.net
>   with an explanation of why your BIOS shouldn't be blacklisted.

I dunno how much there is to add, but I just have a general feeling that 
software suspend and ACPI sleep state support has progressed since this 
was written.



> Compiler issues.
> ~~~~~~~~~~~~~~~~
> - The recommended compiler (for x86) is still 2.95.3.

I'm not sure this is still the case, in practice.  Recent times have 
seen people breaking 2.95.x, which did not support the C99/C++ style of 
mixing variable declarations and code.  People would forget this, and we 
only find out a few days later that the 2.95.x build was broken.



> Networking.
> ~~~~~~~~~~~
> - Some applications may trigger the kernel to spit out warnings about
>   'process xxx using obsolete setsockopt SO_BSDCOMPAT' .
>   - Bind 9.2.2 checks for #ifdef SO_BSDCOMPAT in <asm/socket.h> correctly,
>     so a recompile is all that is needed.
>   - bind9-host from debian testing triggers, though the 'host' package doesn't.
>   - process `snmpd' is using obsolete setsockopt SO_BSDCOMPAT
>   - process `snmptrapd' is using obsolete setsockopt SO_BSDCOMPAT
>   - ntop uses obsolete (PF_INET,SOCK_PACKET)

Wasn't there a recent lkml thread relating to this?

Re: Post-halloween doc updates.

[Holger Schurig]

> - Blank screen after decompressing kernel?
>   Make sure your .config has
>    CONFIG_INPUT=y
>    CONFIG_VT=y
>    CONFIG_VGA_CONSOLE=y
>    CONFIG_VT_CONSOLE=y
>   A lot of people have discovered that taking their .config from 2.4 and
>   running make oldconfig to pick up new options leads to problems, notably
>   with CONFIG_VT not being set.

Would a couple of "default y" entries in Kconfig be a cure against this?

Re: Post-halloween doc updates.

[Dave Jones]

On Thu, Oct 30, 2003 at 10:05:40AM -0500, Jeff Garzik wrote:

 > >  (usually notable by a NIC not getting a DHCP lease for eg, despite being
 > >   sent one by the server). Booting with "noapic" "acpi=off" or a 
 > >   combination
 > >  of both fixes this for most people. Additional breakage reports should go
 > >  to Jeff Garzik <jgarzik@pobox.com>
 > As this is a symptom of irq routing failure, I dunno if bug reports 
 > should necessarily go to me :)

Sorry, you just looked guilty 8-)
Removed that last bit.

 > >Stuff needing forward porting from 2.4.
 > >~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 > >- HFSPlus
 > I think Roman Zippel updated this recently?


 > >- Direct booting from floppy is no longer supported.
 > >  You should now use a boot loader program instead.
 > hmmm, what does this mean?

it means you now need syslinux.

 > "make bzdisk" continues to work...  it requires syslinux, however, so 
 > that the makefile may install the syslinux bootloader on the floppy.

Added a note mentioning that.

 > >- For Red Hat users, there's another pitfall in "/etc/rc.sysinit".
 > > .... deletia 
 > Is this all still true?

Possibly not, I'll look into this.
 
 > >  o  Most PCMCIA devices have unload races and may oops on eject
 > >  o  Modular IDE does not yet work, modular IDE PCI modules sometimes
 > >     oops on loading
 > >  o  ide_scsi is completely broken in 2.6 currently. Known problem.
 > >     If you need it either use 2.4 or fix it 8)
 > also perhaps add a mention of new and spiffy Serial ATA drivers :)

See the very last line of of the doc 8-)

 > >- Jens Axboe added the ability to use DMA for writing CDs on
 > >  ATAPI devices. Writing CDs should be much faster than it
 > >  was in 2.4, and also less prone to buffer underruns and the like.
 > >- With a recent cdrecord, you also no longer need ide-scsi in order to use
 > >  an IDE CD writer.
 > Maybe add a pointer in the IDE section, pointing to this section?  Since 
 > they both mention ide-scsi...

Done.

 > >devfs.
 > >~~~~~~
 > >- devfs got somewhat stripped down and a lot of duplicate functionality
 > >  got removed. You now need to enable CONFIG_DEVPTS_FS=y and mount
 > >  the devpts filesystem in the same manner you would if you were not
 > >  using devfs.
 > Wasn't this mentioned elsewhere in the document?

briefly in the 'obsolete' section. the filesystem changes section
typically has more info.
 
 > >Improved BIOS table support.
 > >~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 > >- Linux now supports various new BIOS extensions.
 > 
 > This is a bit vague.  Even I have no idea what this refers to :)

Then read on...
SBF, EDD & IPMI

 > I dunno how much there is to add, but I just have a general feeling that 
 > software suspend and ACPI sleep state support has progressed since this 
 > was written.

last I tried both were quite dismal, that was a few months back though.


 > >Compiler issues.
 > >~~~~~~~~~~~~~~~~
 > >- The recommended compiler (for x86) is still 2.95.3.
 > 
 > I'm not sure this is still the case, in practice.  Recent times have 
 > seen people breaking 2.95.x, which did not support the C99/C++ style of 
 > mixing variable declarations and code.  People would forget this, and we 
 > only find out a few days later that the 2.95.x build was broken.

*nod*, more and more distros are now shipping gcc3 as their stock compiler,
so it's likely at some point things are going to change.

 > >  'process xxx using obsolete setsockopt SO_BSDCOMPAT' .
 > >  - Bind 9.2.2 checks for #ifdef SO_BSDCOMPAT in <asm/socket.h> correctly,
 > >    so a recompile is all that is needed.
 > >  - bind9-host from debian testing triggers, though the 'host' package 
 > >  doesn't.
 > >  - process `snmpd' is using obsolete setsockopt SO_BSDCOMPAT
 > >  - process `snmptrapd' is using obsolete setsockopt SO_BSDCOMPAT
 > >  - ntop uses obsolete (PF_INET,SOCK_PACKET)
 > 
 > Wasn't there a recent lkml thread relating to this?

not that I recall.

Thanks for the comments.

		Dave

Re: Post-halloween doc updates.

[Dave Jones]

On Thu, Oct 30, 2003 at 04:15:25PM +0100, Holger Schurig wrote:
 > > - Blank screen after decompressing kernel?
 > >   Make sure your .config has
 > >    CONFIG_INPUT=y
 > >    CONFIG_VT=y
 > >    CONFIG_VGA_CONSOLE=y
 > >    CONFIG_VT_CONSOLE=y
 > >   A lot of people have discovered that taking their .config from 2.4 and
 > >   running make oldconfig to pick up new options leads to problems, notably
 > >   with CONFIG_VT not being set.
 > 
 > Would a couple of "default y" entries in Kconfig be a cure against this?

Reports of this problem seem to have tailed off over the last few months
so its entirely possible that this is now fixed.

		Dave

Re: Post-halloween doc updates.

[Randy.Dunlap]

On Thu, 30 Oct 2003 14:15:19 +0000 Dave Jones <davej@redhat.com> wrote:

|                      The post-halloween document. v0.46
|                         (aka, 2.6 - what to expect)
|                     Dave Jones <davej@codemonkey.org.uk>
|                           (Updated as of 2.6.0test9)

| Known gotchas.
| ~~~~~~~~~~~~~~
| Certain known bugs are being reported over and over. Here are the
| workarounds.
| - Can't load any modules? You need updated tools (See modules section below).

  - depmod reports Unresolved symbols?  depmod from modutils instead of
    depmod from module-init-tools is first in $PATH (might be different
    $PATHs as $USER and $ROOT)

| Regressions.
| ~~~~~~~~~~~~
| - Some filesystems still need work (Intermezzo, UFS, HFS, HPFS..)

    + EFS (has a blocksize problem, depending on the device that the
      filesystem is being mounted on)

| Modules.
| ~~~~~~~~
| - Modules now have a .ko suffix instead of .o

    Some (older) versions of 'mkinitrd' don't search for modules
    that end with .ko, so update your mkinitrd if this is a problem.

[
or is this invalid since initrd isn't used any more?
if that's the case, mention it in here somewhere...
need to add anything about initramfs?
]


| Nanosecond stat:
| ~~~~~~~~~~~~~~~~
| The stat64() syscall got changed to return jiffies granularity.
| This allows make(1) to make better decisions on whether or not it
| needs to recompile a file. Not all filesystems may support such precision.

General comment/change:  use 'was changed' instead of 'got changed' (above).
This is the second or third instance that I've noticed where 'got'
should/would better be 'was', so if you would do a global search and
conditional replace for those, that would be Good.


| Generic VFS changes.
| ~~~~~~~~~~~~~~~~~~~~
| - Since Linux 2.5.1 it is possible to atomically move a subtree to
|   another place. The call is...
                       s/call/usage/
|    mount --move olddir newdir


| sysfs.
| ~~~~~~
| In simple terms, the sysfs filesystem is a saner way for
| drivers to export their innards than /proc.
| This filesystem is always compiled in, and can be mounted
| just like another virtual filesystem. No userspace tools
| beyond cat and echo are needed.

  'tree' is also nice for viewing it.

|     mount -t sysfs none /sys
| 
| See Documentation/filesystems/sysfs.txt for more info.
| 
| 
| 
| SELinux.
| ~~~~~~~~
| NSA Security-Enhanced Linux (SELinux) got merged in 2.6.
| It is disabled by default and can be enabled with a boot time parameter
| selinux=1.
| You can obtain SELinux tools and an example policy configuration from
| http://www.nsa.gov/selinux

Somebody correct me here if needed...
selinux can't just be enabled by using 'selinux=1', if the config
options are set for checking that.
The way that I read security/selinux/Kconfig and hooks.c,
if SECURITY_SELINUX_BOOTPARAM is enabled, then the 'selinux'
boot option is also enabled.  However, it can be disabled by using
'selinux=0' as a kernel boot option.

| Networking.
| ~~~~~~~~~~~
| - Users of boxes with >1 NIC may find that for eg, eth0 and eth1 refer to
|   the opposites of what they did in 2.4.   This is a bug that will be fixed
|   before 2.6.0.  One option (or management workaround) for this is to use

It will be?  It's time to do it then, if it's not already done...

|   'nameif' to name Ethernet interfaces.  There is a HOWTO for doing this at
|   <http://xenotime.net/linux/doc/network-interface-names.txt>

| - SCTP (Stream Control Transport Protocol)

RFC 2960 - Stream Control Transmission Protocol



Overall a very good job, Dave.  Thanks for keeping this updated.

--
~Randy

Re: Post-halloween doc updates.

[John Bradford]

>  > >Compiler issues.
>  > >~~~~~~~~~~~~~~~~
>  > >- The recommended compiler (for x86) is still 2.95.3.
>  > 
>  > I'm not sure this is still the case, in practice.  Recent times have 
>  > seen people breaking 2.95.x, which did not support the C99/C++ style of 
>  > mixing variable declarations and code.  People would forget this, and we 
>  > only find out a few days later that the 2.95.x build was broken.
> 
> *nod*, more and more distros are now shipping gcc3 as their stock compiler,

That may be partially motivated by the fact that latest GLIBC no
longer compiles with GCC 2.95.x

> so it's likely at some point things are going to change.

Do you think that GCC > 2.95.x actually produces noticably better code
though?  I'm not convinced yet, and yet compile times can be a lot
higher.

By the way, it might be worth adding something to the input devices
section suggesting that people try forcing set 3 if they have a
keyboard which has keys that are not independently usable, and it's
not a regression since 2.4.  I have such a keyboard, and I saw a post
recently describing similar behavior with a VMS keyboard.

John.

Re: Post-halloween doc updates.

[Geert Uytterhoeven]

On Thu, 30 Oct 2003, Dave Jones wrote:
> Modules.
> ~~~~~~~~
> - Debian sid or Conectiva snapshot users can just use
>   'apt-get install module-init-tools'

It's in Debian sarge, too.

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds

Re: Post-halloween doc updates.

[Chris Wright]

* Randy.Dunlap (rddunlap@osdl.org) wrote:
> | SELinux.
> | ~~~~~~~~
> | NSA Security-Enhanced Linux (SELinux) got merged in 2.6.
> | It is disabled by default and can be enabled with a boot time parameter
> | selinux=1.
> | You can obtain SELinux tools and an example policy configuration from
> | http://www.nsa.gov/selinux
> 
> Somebody correct me here if needed...
> selinux can't just be enabled by using 'selinux=1', if the config
> options are set for checking that.
> The way that I read security/selinux/Kconfig and hooks.c,
> if SECURITY_SELINUX_BOOTPARAM is enabled, then the 'selinux'
> boot option is also enabled.  However, it can be disabled by using
> 'selinux=0' as a kernel boot option.

This is correct.  SELinux defaults to not being config'd in.  If you
config it in it defaults to enabled.  If you also config the bootparam
you can use that param to disable it, otherwise selinux=1 is redundant
as that's the default.

thanks,
-chris
-- 
Linux Security Modules     http://lsm.immunix.org     http://lsm.bkbits.net

Re: Post-halloween doc updates.

[Dave Jones]

On Thu, Oct 30, 2003 at 08:52:22AM -0800, Randy.Dunlap wrote:
 > Overall a very good job, Dave.  Thanks for keeping this updated.

Thanks for the feedback. I've updated the working version[1] of
the doc with your (and everyone elses so far) suggestions.

		Dave

[1] http://www.codemonkey.org.uk/docs/post-halloween-2.6.txt-devel

Re: Post-halloween doc updates.

[Randy.Dunlap]

On Thu, 30 Oct 2003 18:38:56 +0000 Dave Jones <davej@redhat.com> wrote:

| On Thu, Oct 30, 2003 at 08:52:22AM -0800, Randy.Dunlap wrote:
|  > Overall a very good job, Dave.  Thanks for keeping this updated.
| 
| Thanks for the feedback. I've updated the working version[1] of
| the doc with your (and everyone elses so far) suggestions.
| 
| 		Dave
| 
| [1] http://www.codemonkey.org.uk/docs/post-halloween-2.6.txt-devel


Yes, looks good.  But please change this one also:

| - SCTP (Stream Control Transport Protocol)

          Stream Control Transmission Protocol

--
~Randy

Re: Post-halloween doc updates.

[Dave Jones]

On Thu, Oct 30, 2003 at 10:44:50AM -0800, Randy.Dunlap wrote:

 > | [1] http://www.codemonkey.org.uk/docs/post-halloween-2.6.txt-devel
 > Yes, looks good.  But please change this one also:
 > | - SCTP (Stream Control Transport Protocol)
 >           Stream Control Transmission Protocol

Done. Good work eagle-eyes 8-)

		Dave

Re: Post-halloween doc updates.

[Philipp Matthias Hahn]

Hi Dave, LKML!

On Thu, Oct 30, 2003 at 02:15:19PM +0000, Dave Jones wrote:
>                      The post-halloween document. v0.46
...
> Input layer.
...
> - If you find your keyboard/mouse still don't work, edit the file
>   drivers/input/serio/i8042.c, and replace the #undef DEBUG
>   with a #define DEBUG
                        , recompile and reinstall.
> 
>   When you boot, you should now see a lot more debugging information.
>   Forward this information to Vojtech Pavlik <vojtech@suse.cz>

BYtE
Philipp
-- 
  / /  (_)__  __ ____  __ Philipp Hahn
 / /__/ / _ \/ // /\ \/ /
/____/_/_//_/\_,_/ /_/\_\ pmhahn@titan.lahn.de

Re: Post-halloween doc updates.

[bd]

Dave Jones wrote:

> - The format of /proc/stat changed, which could break some
>   applications that still depend on the old layout.
>   Currently the only known application to break is the java
>   'DOTS' app. (http://bugme.osdl.org/show_bug.cgi?id=277)

'xosview' is also broken by this change.

Re: Post-halloween doc updates.

[Felipe Alfaro Solana]

On Thu, 2003-10-30 at 15:15, Dave Jones wrote:

> Process scheduler improvements.
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> - Another much talked about feature. Ingo Molnar reworked the process
>   scheduler to use an O(1) algorithm.  In operation, you should notice
>   no changes with low loads, and increased scalability with large numbers
>   of processes, especially on large SMP systems.

I think we should mention excellent Con Kolivas contributions to the 2.6
kernel scheduler. He did a great job in tunning the scheduler for
maximum interactive feeling.

Re: Post-halloween doc updates.

[Dave Jones]

On Fri, Oct 31, 2003 at 12:11:52AM +0100, Felipe Alfaro Solana wrote:
 > > Process scheduler improvements.
 > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 > > - Another much talked about feature. Ingo Molnar reworked the process
 > >   scheduler to use an O(1) algorithm.  In operation, you should notice
 > >   no changes with low loads, and increased scalability with large numbers
 > >   of processes, especially on large SMP systems.
 > 
 > I think we should mention excellent Con Kolivas contributions to the 2.6
 > kernel scheduler. He did a great job in tunning the scheduler for
 > maximum interactive feeling.

With no disrespect to Con, I'm not going to do this, or I'll end up
spending far too much time adding credits to everyone whoever improved
something in 2.5.  There's a place for such stuff, and it's aptly named
'CREDITS' in toplevel of src dir.

		Dave

Re: Post-halloween doc updates.

[Gene Heskett]

On Thursday 30 October 2003 17:16, bd wrote:
>Dave Jones wrote:
>> - The format of /proc/stat changed, which could break some
>>   applications that still depend on the old layout.
>>   Currently the only known application to break is the java
>>   'DOTS' app. (http://bugme.osdl.org/show_bug.cgi?id=277)
>
>'xosview' is also broken by this change.
>
I can confirm this, also xawtv and gnomeradio, neither can apparently 
see the devices registered in at boot time according to grepping 
/var/log/messages.

>-
>To unsubscribe from this list: send the line "unsubscribe
> linux-kernel" in the body of a message to majordomo@vger.kernel.org
>More majordomo info at  http://vger.kernel.org/majordomo-info.html
>Please read the FAQ at  http://www.tux.org/lkml/

-- 
Cheers, Gene
AMD K6-III@500mhz 320M
Athlon1600XP@1400mhz  512M
99.27% setiathome rank, not too shabby for a WV hillbilly
Yahoo.com attornies please note, additions to this message
by Gene Heskett are:
Copyright 2003 by Maurice Eugene Heskett, all rights reserved.

Re: Post-halloween doc updates.

[John Levon]

On Fri, Oct 31, 2003 at 12:16:08AM +0000, Dave Jones wrote:

>  > > - Another much talked about feature. Ingo Molnar reworked the process
>  > >   scheduler to use an O(1) algorithm.  In operation, you should notice
>  > >   no changes with low loads, and increased scalability with large numbers
>  > >   of processes, especially on large SMP systems.
>  > 
>  > I think we should mention excellent Con Kolivas contributions to the 2.6
>  > kernel scheduler. He did a great job in tunning the scheduler for
>  > maximum interactive feeling.
> 
> With no disrespect to Con, I'm not going to do this, or I'll end up
> spending far too much time adding credits to everyone whoever improved
> something in 2.5.  There's a place for such stuff, and it's aptly named
> 'CREDITS' in toplevel of src dir.

Given that Ingo's reworkings led to horrendous interactive performance
for many desktop users for a long time during 2.5, it seems a little odd
to prefer crediting Ingo over Con given what you've said. How about just
mentioning that we have an O(1) scheduler, plus there has been
significant work on interactive performance.

john
-- 
Khendon's Law:
If the same point is made twice by the same person, the thread is over.

Re: Post-halloween doc updates.

[Dave Jones]

On Fri, Oct 31, 2003 at 02:14:25AM +0000, John Levon wrote:

 > Given that Ingo's reworkings led to horrendous interactive performance
 > for many desktop users for a long time during 2.5, it seems a little odd
 > to prefer crediting Ingo over Con given what you've said.
 > mentioning that we have an O(1) scheduler, plus there has been
 > significant work on interactive performance.

Preference has nothing to do with it. It comes down to one
definitive source of information.

>From MAINTAINERS ..

SCHEDULER
P:  Ingo Molnar
M:  mingo@elte.hu
P:  Robert Love    [the preemptible kernel bits]
M:  rml@tech9.net
L:  linux-kernel@vger.kernel.org
S:  Maintained

Shall I add rml there too? How about the other dozen or so people
that hacked on O(1) over the last year or so?  Get real, I'm
not about to waste my time going over attributions, nor further
entertain any responses in this thread.

		Dave

Re: ide-scsi is working [was: Post-halloween doc updates.]

[Nuno Silva]

Hi!!


Dave Jones wrote:

[...]

> 
> IDE.
> ~~~~

[...]

>   o  ide_scsi is completely broken in 2.6 currently. Known problem.
>      If you need it either use 2.4 or fix it 8)


I have 2.6.0-test9 and I just recorded knoppix to CD with ide-scsi. In 
fact, it never stopped working, in this box, with several 2.6.* kernels.

Hmmmm maybe it's because my cdrecorder is USB?

The box has debian sid and cdrecord is:

puma:/# cdrecord -scanbus
Cdrecord-Clone 2.01a19 (i686-pc-linux-gnu) Copyright (C) 1995-2003 Jörg 
Schilling
Linux sg driver version: 3.5.29
Using libscg version 'schily-0.7'
scsibus2:
         2,0,0   200) 'HP      ' 'CD-Writer cd4f  ' '1.0A' Removable CD-ROM
         2,1,0   201) *
         2,2,0   202) *
         2,3,0   203) *
         2,4,0   204) *
         2,5,0   205) *
         2,6,0   206) *
         2,7,0   207) *
scsibus3:
         3,0,0   300) 'HP      ' 'psc 2210        ' '1.00' Removable Disk
         3,1,0   301) *
         3,2,0   302) *
         3,3,0   303) *
         3,4,0   304) *
         3,5,0   305) *
         3,6,0   306) *
         3,7,0   307) *
puma:/#

Just to be clear: I *can* record cd's! :-)

Can I provide any more info?

Regards,
Nuno Silva

Re: Post-halloween doc updates.

[Andreas Jellinghaus]

On Thu, 30 Oct 2003 14:19:47 +0000, Dave Jones wrote:
> Deprecated/obsolete features.
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> - devfs has been obsoleted in favour of udev (http://www.kernel.org/pub/linux/utils/kernel/hotplug/)

s/has been obsoleted/will be olsoleted some day/

many devices need to be added to sysfs,
before udev+sysfs can replace devfs.

Re: Post-halloween doc updates.

[Thierry Vignaud]

bd <bdonlan@users.sourceforge.net> writes:

> > - The format of /proc/stat changed, which could break some
> >   applications that still depend on the old layout.
> >   Currently the only known application to break is the java
> >   'DOTS' app. (http://bugme.osdl.org/show_bug.cgi?id=277)
> 
> 'xosview' is also broken by this change.

there's a patch around the net that fix it (alternatively, you got it
from the xosview source rpm from mandrake contribs)

Re: ide-scsi is working [was: Post-halloween doc updates.]

[Bartlomiej Zolnierkiewicz]

On Friday 31 of October 2003 08:34, Nuno Silva wrote:
> Hi!!
>
>
> Dave Jones wrote:
>
> [...]
>
> > IDE.
> > ~~~~
>
> [...]
>
> >   o  ide_scsi is completely broken in 2.6 currently. Known problem.
> >      If you need it either use 2.4 or fix it 8)
>
> I have 2.6.0-test9 and I just recorded knoppix to CD with ide-scsi. In
> fact, it never stopped working, in this box, with several 2.6.* kernels.
>
> Hmmmm maybe it's because my cdrecorder is USB?

So you don't even use ide-scsi... and it is broken.

--bartlomiej

Re: Post-halloween doc updates.

[Ian Soboroff]

And APM suspend seems to have broken in -test8.  Does it work for
anyone?

Ian

Dave Jones <davej@redhat.com> writes:

> Power management.
> ~~~~~~~~~~~~~~~~~
> - 2.6 contains a more up to date snapshot of the ACPI driver. Should
>   you experience any problems booting, try booting with the argument
>   "acpi=off" to rule out any ACPI interaction. ACPI has a much more involved
>   role in bringing the system up in 2.6 than it did in 2.4
> - The old "acpismp=force" boot option is now obsolete, and will be ignored
>   due to the old "mini ACPI" parser being removed.
> - software suspend is still in development, and in need of more work.
>   Use with SMP and/or PREEMPT not advised.
> - The ACPI code will do basic sanity checks on the DMI structure in the BIOS
>   to determine the date it was written. BIOSes older than year 2000 are
>   assumed to be broken. In some circumstances, this assumption is wrong.
>   If you see a message saying ACPI is disabled for this reason, try booting
>   with acpi=force. If things work fine, send the output of dmidecode
>   (http://www.nongnu.org/dmidecode/) to acpi-devel@lists.sf.net
>   with an explanation of why your BIOS shouldn't be blacklisted.

Re: Post-halloween doc updates.

[Russell King]

On Fri, Oct 31, 2003 at 10:06:31AM -0500, Ian Soboroff wrote:
> And APM suspend seems to have broken in -test8.  Does it work for
> anyone?

Doesn't work for me.

Now, taking off my "open source co-operative hat" and placing my
"reality" hat on, I'd suggest that anyone who finds that APM doesn't
work to consider it a dead loss - It's an obsolete technology, and
therefore no one is interested in it anymore.  I've reported the
problem multiple times here and there's been very little, if any,
reaction, so this seems to back that up.

Now, imagine the PCMCIA maintainer being unable to test the suspend/
resume functionality during the stability freeze.  Oh, sorry, you
don't have to imagine that hard. 8)

> Dave Jones <davej@redhat.com> writes:
> 
> > Power management.
> > ~~~~~~~~~~~~~~~~~
> > - 2.6 contains a more up to date snapshot of the ACPI driver. Should
> >   you experience any problems booting, try booting with the argument
> >   "acpi=off" to rule out any ACPI interaction. ACPI has a much more involved
> >   role in bringing the system up in 2.6 than it did in 2.4
> > - The old "acpismp=force" boot option is now obsolete, and will be ignored
> >   due to the old "mini ACPI" parser being removed.
> > - software suspend is still in development, and in need of more work.
> >   Use with SMP and/or PREEMPT not advised.
> > - The ACPI code will do basic sanity checks on the DMI structure in the BIOS
> >   to determine the date it was written. BIOSes older than year 2000 are
> >   assumed to be broken. In some circumstances, this assumption is wrong.
> >   If you see a message saying ACPI is disabled for this reason, try booting
> >   with acpi=force. If things work fine, send the output of dmidecode
> >   (http://www.nongnu.org/dmidecode/) to acpi-devel@lists.sf.net
> >   with an explanation of why your BIOS shouldn't be blacklisted.

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 PCMCIA      - http://pcmcia.arm.linux.org.uk/
                 2.6 Serial core

Re: Post-halloween doc updates.

[Paul Dickson]

On Fri, 31 Oct 2003 13:25:08 +0100, Andreas Jellinghaus wrote:

> On Thu, 30 Oct 2003 14:19:47 +0000, Dave Jones wrote:
> > Deprecated/obsolete features.
> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > - devfs has been obsoleted in favour of udev (http://www.kernel.org/pub/linux/utils/kernel/hotplug/)
> 
> s/has been obsoleted/will be olsoleted some day/
> 
> many devices need to be added to sysfs,
> before udev+sysfs can replace devfs.

So the correct term should be deprecated rather than obsoleted.  Which can
be taken to mean "please which switch when possible".

	-Paul

Re: Post-halloween doc updates.

[Ingo Oeser]

Hi Dave,
hi lkml,

On Thursday 30 October 2003 15:15, Dave Jones wrote:
> Threading improvements.
> ~~~~~~~~~~~~~~~~~~~~~~~
> - Ingo Molnar put a lot of work into threading improvements for 2.6.
>   Some of the features of this work are:
>   -  Generic pid allocator (arbitrary number of PIDs with no slowdown,
>      unified pidhash).
>   -  Thread Local Storage syscalls
>   -  sys_clone() enhancements (CLONE_SETTLS, CLONE_PARENT_SETTID,
> CLONE_SETTID, CLONE_CLEARTID, CLONE_DETACHED)
>   -  POSIX thread signals stuff (atomic signals, shared signals, etc.)
>   -  Per-CPU GDT
>   -  Threaded coredumping support
>   -  sys_exit() speedups (O(1) exit)
>   -  Generic, improved futexes, vcache

vcache is gone. futex pages are swappable now and not pinned anymore.

Good work. I love this document ;-)

Regards

Ingo Oeser

Re: Post-halloween doc updates.

[Aristeu Sergio Rozanski Filho]

> > And APM suspend seems to have broken in -test8.  Does it work for
> > anyone?
> 
> Doesn't work for me.
works for me. it isn't rock solid as in 2.4 but most times it resumes
without problems even using dma on ide controller (in 2.4 i should
disable dma before suspend and couldn't enable it later).

> Now, taking off my "open source co-operative hat" and placing my
> "reality" hat on, I'd suggest that anyone who finds that APM doesn't
> work to consider it a dead loss - It's an obsolete technology, and
> therefore no one is interested in it anymore.  I've reported the
> problem multiple times here and there's been very little, if any,
> reaction, so this seems to back that up.
i guess it isn't exactly the problem. maybe there's no _developers_ with
time and skills to work on it. i would do it if i have enough skills.
when stock 2.6 comes out we'll have a lot of people complaining
about APM because there a lot of notebooks out there that still needs
it. including mine.

--
aris

Re: Post-halloween doc updates.

[Ian Soboroff]

Russell King <rmk+lkml@arm.linux.org.uk> writes:

> On Fri, Oct 31, 2003 at 10:06:31AM -0500, Ian Soboroff wrote:
>> And APM suspend seems to have broken in -test8.  Does it work for
>> anyone?
>
> Doesn't work for me.
>
> Now, taking off my "open source co-operative hat" and placing my
> "reality" hat on, I'd suggest that anyone who finds that APM doesn't
> work to consider it a dead loss - It's an obsolete technology, and
> therefore no one is interested in it anymore.  I've reported the
> problem multiple times here and there's been very little, if any,
> reaction, so this seems to back that up.

Well, ok, but the alternatives are ACPI, which has always been spotty,
and two competing power management schemes from Patrick and Pavel,
neither of which seem to actually work yet.  Wouldn't it be nice to
have at least one working method of putting a laptop to sleep?

Once I get some free time (maybe next week, who knows) I'll try
backing out bits of the -test8 patch to see what broke.  In the
meantime, -test7 works great.

Ian

Re: Post-halloween doc updates.

[Russell King]

On Fri, Oct 31, 2003 at 11:03:52AM -0500, Ian Soboroff wrote:
> Well, ok, but the alternatives are ACPI, which has always been spotty,

Wrong - there are systems out there which do not support ACPI (or maybe
the kernel doesn't support the ACPI which is implemented in them.)

> and two competing power management schemes from Patrick and Pavel,
> neither of which seem to actually work yet.  Wouldn't it be nice to
> have at least one working method of putting a laptop to sleep?

Indeed.  With 2.6 there are zero ways I can make my x86 laptop
suspend or hibernate.

> Once I get some free time (maybe next week, who knows) I'll try
> backing out bits of the -test8 patch to see what broke.  In the
> meantime, -test7 works great.

Oh, my problem goes back many kernel versions.  It's nothing new.
Somewhere during 2.5 development (current thinking is somewhere
around 2.5.3x) something changed which makes the APM BIOS believe
that the machine isn't in the correct state to suspend.

However, exactly what that is seems to be impossible to track down.
Building a kernel minimal driver support results in a system which
can't suspend... and by "minimal" that includes dropping stuff like
the input layer and console completely from the kernel.

It basically comes down to some really subtle change in what 2.6 is
does differently from 2.4.

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 PCMCIA      - http://pcmcia.arm.linux.org.uk/
                 2.6 Serial core

Re: Post-halloween doc updates.

[Michael Clark]

On 11/01/03 00:03, Ian Soboroff wrote:
> Russell King <rmk+lkml@arm.linux.org.uk> writes:
> 
> 
>>On Fri, Oct 31, 2003 at 10:06:31AM -0500, Ian Soboroff wrote:
>>
>>>And APM suspend seems to have broken in -test8.  Does it work for
>>>anyone?
>>
>>Doesn't work for me.

APM working here nicely with -test9 on Thinkpad A31. Stilling getting
1394 badness when suspending/resuming with my cardbus 1394 controller
plugged in. Other than that, works pretty seamlessy with no cardbus
cards plugged.

Even radeon with VESA suspend/resume, DRI and X 4.3 (using some
precarious vtswitch calls in /etc/apm/event.d/). wlan-ng works okay
although it requires rmmod/modprobe to wake up properly after resume.

>>Now, taking off my "open source co-operative hat" and placing my
>>"reality" hat on, I'd suggest that anyone who finds that APM doesn't
>>work to consider it a dead loss - It's an obsolete technology, and
>>therefore no one is interested in it anymore.  I've reported the
>>problem multiple times here and there's been very little, if any,
>>reaction, so this seems to back that up.

Hmmm, well for me; a working APM (here) is much prefered to non-
working ACPI suspend/resume. I'd prefer not to obsolete APM until
there is a working alternative (with mature userspace tools).

~mc

Re: Post-halloween doc updates.

[Junio C Hamano]

Could you add the following to the Regressions section?

- In 2.4 users of Japanese keyboards were able to type '|' or
  '\' characters without loading any custom keymap on the
  console.  With the keymap in 2.6, this is not possible
  anymore.  People with these keyboards have to load a keymap
  with loadkeys rebuilt from the source, since loadkeys in some
  vendor distributions cannot load keycodes larger than 127.
  There is a patch to fix this, but it has not been integrated
  (http://tinyurl.com/t75a).

Re: Post-halloween doc updates.

[Sam Ravnborg]

On Thu, Oct 30, 2003 at 02:15:19PM +0000, Dave Jones wrote:
> Modules.
> ~~~~~~~~
> - Modules now have a .ko suffix instead of .o
- Building external modules requires the use of kbuild, so a full kernel
  src package is needed. See also Documentation/kbuild/modules.txt

> Kernel build system.
> ~~~~~~~~~~~~~~~~~~~~
I suggest the following ordering and content:

 - The build system is much improved compared to 2.4.
   You should notice quicker builds, and no spontaneous rebuilds of files
   on subsequent builds from already built trees.
 - There are two new graphical config tools.
   "make xconfig" requires the qt libraries.
   "make gconfig" requires gtk libraries.
 - Make menuconfig/oldconfig has no user-visible changes other than speed,
   whilst numerous improvements have been made.
 - 'make help' provides a list of typical targets, including several new
   debugging targets ('allyesconfig' 'allnoconfig' 'allmodconfig' + more).
 - "make" is now the preferred command, without a target; it builds
   <arch-zimage> and modules. See 'make help' for what is built by default.
 - "make -jN" is now the preferred parallel-make execution.
   Do not bother to provide "MAKE=xxx"
 - Output files can be directed to an alternative directory. Use 'make O=dir'
   to locate all output files (including .config) in 'dir'.
 - The build is now much less verbose.  If you want to see exactly what's
   going on, try "make V=1" or set KBUILD_VERBOSE=1 in your environment.
 - 'make kernel/mm.o' will build the named file, provided a
   corresponding source exists. This also works for (non-composite)
   modules.
 - 'make kernel/' will recursively build all files in the specified
   subdirectory and below.
 - 'make dep' has been obsoleted and does no longer have any effect.
 - Note: The new configuration system is not CML2 related.
 - Also note: Whilst some ideas were taken from it, Keith Owens'
   kbuild-2.5 project was not integrated.

	Sam

Re: Post-halloween doc updates.

[Pavel Machek]

Hi!

> Doesn't work for me.
> 
> Now, taking off my "open source co-operative hat" and placing my
> "reality" hat on, I'd suggest that anyone who finds that APM doesn't
> work to consider it a dead loss - It's an obsolete technology, and
> therefore no one is interested in it anymore. 
Actually APM is so simple technology (very similar to ACPI S1)
that I'm reasonably sure we'll get it working in 2.6.5.

-- 
				Pavel
Written on sharp zaurus, because my Velo1 broke. If you have Velo you don't need...

Re: Post-halloween doc updates.

[bill davidsen]

In article <9cfn0bhjswn.fsf@rogue.ncsl.nist.gov>,
Ian Soboroff  <ian.soboroff@nist.gov> wrote:

| Well, ok, but the alternatives are ACPI, which has always been spotty,
| and two competing power management schemes from Patrick and Pavel,
| neither of which seem to actually work yet.  Wouldn't it be nice to
| have at least one working method of putting a laptop to sleep?

I have no problem putting the laptop to sleep. On the other hand, waking
it up...
-- 
bill davidsen <davidsen@tmr.com>
  CTO, TMR Associates, Inc
Doing interesting things with little computers since 1979.

Re: Post-halloween doc updates.

[Rob Landley]

On Monday 10 November 2003 17:43, bill davidsen wrote:
> In article <9cfn0bhjswn.fsf@rogue.ncsl.nist.gov>,
>
> Ian Soboroff  <ian.soboroff@nist.gov> wrote:
> | Well, ok, but the alternatives are ACPI, which has always been spotty,
> | and two competing power management schemes from Patrick and Pavel,
> | neither of which seem to actually work yet.  Wouldn't it be nice to
> | have at least one working method of putting a laptop to sleep?
>
> I have no problem putting the laptop to sleep. On the other hand, waking
> it up...

Which suspend version are you using?  echo -n "4">/proc/acpi/something or echo 
-n "disk" > sys/power/state?

The second works for me (for a slightly malleable value of "works": resume has 
never failed on me, suspend works maybe 9 times out of 10, and either 
immediately resumes without power down (apparently with no harm done, it just 
didn't work) or panics the rest of the time).

The first has never come close to working (for me).

Rob