hard disk dirver

hard disk dirver

[horseriver]

hi:)

  At booting time ,bootloader loads kernel from hard disk too memory.
  During this period,does it need hd driver's support .

thanks!

hard disk dirver

[horseriver]

 
  Thanks for your reply!

  After grub load kernel and initrd , it get around root filesystem mounting ,
  but failed with no finding root device ,from which kernel and initrd have been 
  located .
  
  ls /dev/ ;  there is no disk device node  .  

  Why?  


  

hard disk dirver

[horseriver]

On Wed, Feb 06, 2013 at 02:35:47AM -0500, Valdis.Kletnieks at vt.edu wrote:
> On Wed, 06 Feb 2013 05:37:41 +0800, horseriver said:
> >   After grub load kernel and initrd , it get around root filesystem mounting ,
> >   but failed with no finding root device ,from which kernel and initrd have been
> >   located .
> >
> >   ls /dev/ ;  there is no disk device node  .
> >
> >   Why?
> 
> Any number of possible reasons, anything from an improperly configured
> kernel, to a misbuilt initrd, to a root= parameter that points 

  root = ?   You mean the aasignment at grub command line  ?

  thanks!

hard disk dirver

[Valdis.Kletnieks at vt.edu]

On Wed, 06 Feb 2013 02:53:11 +0800, horseriver said:
>   At booting time ,bootloader loads kernel from hard disk too memory.
>   During this period,does it need hd driver's support .

Think for a bit - at that point, the hd driver hasn't been loaded
yet, so it *can't* need the hd driver's support.  So instead, the
bootloader has a very dumb simplistic driver that's stripped down
(for instance, no queued command support, one I/O in flight at a
time, very little error handling, read operations only , etc etc)
that's just enough to load the kernel and initrd. (There's often
also a very stupid filesystem driver, just enough to read files.
So for instance 'grub' can find the files for the kernel and initrd.
Some bootloaders are too stupid for even that, and you have to
run a special program to tell the boot loader where all the blocks
of the file are (I'm looking at you, LILO :)

Once the bootloader gets the kernel and initrd loaded, *then* the
kernel can initialize the production driver with all the bells and
whistles needed.
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hard disk dirver

[horseriver]

hi:)

   I have a newbie question about hard ware.
   At booting stage,kernel need to detect the hard device before mount it,
   does this work  need pci's surport?

   At loading stage ,boot loader need to move binaries from hard disk partition
   to ram,does this work need pci's surport?

thanks! 

hard disk dirver

[Valdis.Kletnieks at vt.edu]

On Wed, 06 Feb 2013 05:37:41 +0800, horseriver said:
>   After grub load kernel and initrd , it get around root filesystem mounting ,
>   but failed with no finding root device ,from which kernel and initrd have been
>   located .
>
>   ls /dev/ ;  there is no disk device node  .
>
>   Why?

Any number of possible reasons, anything from an improperly configured
kernel, to a misbuilt initrd, to a root= parameter that points someplace
broken, to....
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hard disk dirver

[Valdis.Kletnieks at vt.edu]

On Wed, 06 Feb 2013 13:21:17 +0800, horseriver said:
>    At booting stage,kernel need to detect the hard device before mount it,
>    does this work  need pci's surport?

That depends.  Is the controller for the hard drive a PCI-based controller? On
most x86-based boxes, it is (and I'm not sure it's even possible to build an
x86 kernel that doesn't have PCI as a =y in the config).  However, very old
units may still have ISA based disk controllers, and other archs may have other
I/O buses.

>    At loading stage ,boot loader need to move binaries from hard disk partition
>    to ram,does this work need pci's surport?

Same as above.
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hard disk dirver

[Valdis.Kletnieks at vt.edu]

On Wed, 06 Feb 2013 12:30:37 +0800, horseriver said:

>   root = ?   You mean the aasignment at grub command line  ?

For instance, the grub entry for the kernel I'm running right now:

title 3.8.0-rc6-next-20130206
        kernel /vmlinuz-3.8.0-rc6-next-20130206 ro root=/dev/mapper/vg_blackice-root log_buf_len=2M vga=893 loglevel=4 thre
adirqs intel_iommu=off LANG=en_US.UTF-8
        initrd /initramfs-3.8.0-rc6-next-20130206.img

(Strictly speaking, it's not the grub command line, it's the kernel command
line that is passed to the kernel by grub or lilo or grub2 or syslinux
or whatever boot loader happens to float your boat).
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hard disk dirver

[Greg Freemyer]

On Wed, Feb 6, 2013 at 12:50 PM, <Valdis.Kletnieks@vt.edu> wrote:

> On Wed, 06 Feb 2013 13:21:17 +0800, horseriver said:
> >    At booting stage,kernel need to detect the hard device before mount
> it,
> >    does this work  need pci's surport?
>
> That depends.  Is the controller for the hard drive a PCI-based
> controller? On
> most x86-based boxes, it is (and I'm not sure it's even possible to build
> an
> x86 kernel that doesn't have PCI as a =y in the config).  However, very old
> units may still have ISA based disk controllers, and other archs may have
> other
> I/O buses.


Most new MB's have a SATA controller directly on the MB connected directly
to either the North or South bridge (I don't know which).

I don't think any PCI is support needed to talk to the boot disk.

Greg
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hard disk dirver

[Valdis.Kletnieks at vt.edu]

On Wed, 06 Feb 2013 13:20:13 -0500, Greg Freemyer said:

> Most new MB's have a SATA controller directly on the MB connected directly
> to either the North or South bridge (I don't know which).
>
> I don't think any PCI is support needed to talk to the boot disk.

Yes, but said SATA controller and north/southbridge are usually emulating
a PCI:

% lspci
00:00.0 Host bridge: Intel Corporation Mobile 4 Series Chipset Memory Controller Hub (rev 07)
00:01.0 PCI bridge: Intel Corporation Mobile 4 Series Chipset PCI Express Graphics Port (rev 07)
....
00:1f.2 RAID bus controller: Intel Corporation 82801 Mobile SATA Controller [RAID mode] (rev 03)

So no actual PCI slots involved there, but that PCI bridge is going to require
PCI support to program all the BARs and other stuff to talk to that 82801.
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hard disk dirver

[Peter Teoh]

On Wed, Feb 6, 2013 at 1:21 PM, horseriver <horserivers@gmail.com> wrote:

> hi:)
>
>    I have a newbie question about hard ware.
>    At booting stage,kernel need to detect the hard device before mount it,
>    does this work  need pci's surport?
>

>    At loading stage ,boot loader need to move binaries from hard disk
> partition
>    to ram,does this work need pci's surport?
>

hard disk I/O is in ATA bus, and PCI has it own bus on the chipset (see
page 69):

http://downloadmirror.intel.com/19123/eng/d525mw_d525mwv_techprodspec.pdf

and page 14:

http://download.intel.com/support/motherboards/desktop/d865gsa/sb/d5600601us.pdf

But these are terminologies.   At the source code level, (and tools as
well), PCI and ATA are not differentiated much:

in drivers/ata/ata_piix.c, and in drivers/pci/quirks.c both directory u can
see 82801 symbols exists.

For your problem i think it is a BOCHS problem...mixing with recent linux
kernel (older kernel should be fine)...eg,

http://forums.gentoo.org/viewtopic-t-915210-view-previous.html?sid=a003ebbc022d7f23399fc7f1c5dad424

(notice the 3.2 kernel) which is resolved via setting the PCI configuration
in BOCHS as well.   take a look.


> thanks!
>



-- 
Regards,
Peter Teoh
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