[RFC PATCH v2 0/2] Documentation/admin-guide: remove use of "rdev"

[RFC PATCH v2 0/2] Documentation/admin-guide: remove use of "rdev"

[Randy Dunlap]

Remove mention of using "rdev" to set boot device, video mode,
or ramdisk information for the booting kernel.


Cc: Karel Zak <kzak@redhat.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Martin Mares <mj@ucw.cz>
Cc: linux-video@atrey.karlin.mff.cuni.cz
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org


 [RFC PATCH 1/2] Documentation/admin-guide: README & svga: remove use of "rdev"
 [RFC PATCH 2/2] Documentation/admin-guide: blockdev/ramdisk: remove use of "rdev"

 Documentation/admin-guide/README.rst            |    6 -
 Documentation/admin-guide/blockdev/ramdisk.rst  |   70 ++++----------
 Documentation/admin-guide/kernel-parameters.txt |    9 -
 Documentation/admin-guide/svga.rst              |    6 -
 4 files changed, 33 insertions(+), 58 deletions(-)

[RFC PATCH v2 1/2] Documentation/admin-guide: README & svga: remove use of "rdev"

[Randy Dunlap]

"rdev" is considered antiquated, ancient, archaic, obsolete, deprecated
{choose any or all}.

Remove use of "rdev" and "vidmode" (a symlink to rdev) in
admin-guide/README.rst and admin-guide/svga.rst.

"rdev" was removed from util-linux in 2010:
  https://git.kernel.org/pub/scm/utils/util-linux/util-linux.git/commit/?id=a3e40c14651fccf18e7954f081e601389baefe3f

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Karel Zak <kzak@redhat.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Martin Mares <mj@ucw.cz>
Cc: linux-video@atrey.karlin.mff.cuni.cz
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
---
v2: Modify when the Video Mode Selection feature is available (thanks, Peter).

No email address for these:
 nCc: Werner Almesberger
 nCc: Stephen Tweedie
 nCc: Peter MacDonald

 Documentation/admin-guide/README.rst |    6 +++---
 Documentation/admin-guide/svga.rst   |    7 ++++---
 2 files changed, 7 insertions(+), 6 deletions(-)

--- lnx-59-rc5.orig/Documentation/admin-guide/README.rst
+++ lnx-59-rc5/Documentation/admin-guide/README.rst
@@ -322,9 +322,9 @@ Compiling the kernel
    reboot, and enjoy!
 
    If you ever need to change the default root device, video mode,
-   ramdisk size, etc.  in the kernel image, use the ``rdev`` program (or
-   alternatively the LILO boot options when appropriate).  No need to
-   recompile the kernel to change these parameters.
+   etc. in the kernel image, use your bootloader's boot options
+   where appropriate.  No need to recompile the kernel to change
+   these parameters.
 
  - Reboot with the new kernel and enjoy.
 
--- lnx-59-rc5.orig/Documentation/admin-guide/svga.rst
+++ lnx-59-rc5/Documentation/admin-guide/svga.rst
@@ -12,7 +12,8 @@ Intro
 This small document describes the "Video Mode Selection" feature which
 allows the use of various special video modes supported by the video BIOS. Due
 to usage of the BIOS, the selection is limited to boot time (before the
-kernel decompression starts) and works only on 80X86 machines.
+kernel decompression starts) and works only on 80X86 machines that are
+booted through BIOS firmware (as opposed to through UEFI, kexec, etc.).
 
 .. note::
 
@@ -23,7 +24,7 @@ kernel decompression starts) and works o
 
 The video mode to be used is selected by a kernel parameter which can be
 specified in the kernel Makefile (the SVGA_MODE=... line) or by the "vga=..."
-option of LILO (or some other boot loader you use) or by the "vidmode" utility
+option of LILO (or some other boot loader you use) or by the "xrandr" utility
 (present in standard Linux utility packages). You can use the following values
 of this parameter::
 
@@ -41,7 +42,7 @@ of this parameter::
       better to use absolute mode numbers instead.
 
    0x.... - Hexadecimal video mode ID (also displayed on the menu, see below
-      for exact meaning of the ID). Warning: rdev and LILO don't support
+      for exact meaning of the ID). Warning: LILO doesn't support
       hexadecimal numbers -- you have to convert it to decimal manually.
 
 Menu

[RFC PATCH v2 2/2] Documentation/admin-guide: blockdev/ramdisk: remove use of "rdev"

[Randy Dunlap]

Remove use of "rdev" from blockdev/ramdisk.rst and update
admin-guide/kernel-parameters.txt.

"rdev" is considered antiquated, ancient, archaic, obsolete, deprecated
{choose any or all}.

"rdev" was removed from util-linux in 2010:
  https://git.kernel.org/pub/scm/utils/util-linux/util-linux.git/commit/?id=a3e40c14651fccf18e7954f081e601389baefe3f

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Karel Zak <kzak@redhat.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Martin Mares <mj@ucw.cz>
Cc: linux-video@atrey.karlin.mff.cuni.cz
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
---
v2: modify Changelog date format.

No email address for these:
 nCc: Werner Almesberger
 nCc: Stephen Tweedie
 nCc: Peter MacDonald

 Documentation/admin-guide/blockdev/ramdisk.rst  |   70 ++++----------
 Documentation/admin-guide/kernel-parameters.txt |    9 -
 2 files changed, 27 insertions(+), 52 deletions(-)

--- lnx-59-rc5.orig/Documentation/admin-guide/blockdev/ramdisk.rst
+++ lnx-59-rc5/Documentation/admin-guide/blockdev/ramdisk.rst
@@ -6,7 +6,7 @@ Using the RAM disk block device with Lin
 
 	1) Overview
 	2) Kernel Command Line Parameters
-	3) Using "rdev -r"
+	3) Using "rdev"
 	4) An Example of Creating a Compressed RAM Disk
 
 
@@ -59,51 +59,27 @@ default is 4096 (4 MB).
 	rd_size
 		See ramdisk_size.
 
-3) Using "rdev -r"
-------------------
+3) Using "rdev"
+---------------
 
-The usage of the word (two bytes) that "rdev -r" sets in the kernel image is
-as follows. The low 11 bits (0 -> 10) specify an offset (in 1 k blocks) of up
-to 2 MB (2^11) of where to find the RAM disk (this used to be the size). Bit
-14 indicates that a RAM disk is to be loaded, and bit 15 indicates whether a
-prompt/wait sequence is to be given before trying to read the RAM disk. Since
-the RAM disk dynamically grows as data is being written into it, a size field
-is not required. Bits 11 to 13 are not currently used and may as well be zero.
-These numbers are no magical secrets, as seen below::
-
-  ./arch/x86/kernel/setup.c:#define RAMDISK_IMAGE_START_MASK     0x07FF
-  ./arch/x86/kernel/setup.c:#define RAMDISK_PROMPT_FLAG          0x8000
-  ./arch/x86/kernel/setup.c:#define RAMDISK_LOAD_FLAG            0x4000
-
-Consider a typical two floppy disk setup, where you will have the
-kernel on disk one, and have already put a RAM disk image onto disk #2.
-
-Hence you want to set bits 0 to 13 as 0, meaning that your RAM disk
-starts at an offset of 0 kB from the beginning of the floppy.
-The command line equivalent is: "ramdisk_start=0"
-
-You want bit 14 as one, indicating that a RAM disk is to be loaded.
-The command line equivalent is: "load_ramdisk=1"
-
-You want bit 15 as one, indicating that you want a prompt/keypress
-sequence so that you have a chance to switch floppy disks.
-The command line equivalent is: "prompt_ramdisk=1"
-
-Putting that together gives 2^15 + 2^14 + 0 = 49152 for an rdev word.
-So to create disk one of the set, you would do::
-
-	/usr/src/linux# cat arch/x86/boot/zImage > /dev/fd0
-	/usr/src/linux# rdev /dev/fd0 /dev/fd0
-	/usr/src/linux# rdev -r /dev/fd0 49152
+"rdev" is an obsolete, deprecated, antiquated utility that could be used
+to set the boot device in a Linux kernel image.
 
-If you make a boot disk that has LILO, then for the above, you would use::
+Instead of using rdev, just place the boot device information on the
+kernel command line and pass it to the kernel from the bootloader.
+
+You can also pass arguments to the kernel by setting FDARGS in
+arch/x86/boot/Makefile and specify in initrd image by setting FDINITRD in
+arch/x86/boot/Makefile.
 
-	append = "ramdisk_start=0 load_ramdisk=1 prompt_ramdisk=1"
+Some of the kernel command line boot options that may apply here are::
 
-Since the default start = 0 and the default prompt = 1, you could use::
+  ramdisk_start=N
+  ramdisk_size=M
 
-	append = "load_ramdisk=1"
+If you make a boot disk that has LILO, then for the above, you would use::
 
+	append = "ramdisk_start=N ramdisk_size=M"
 
 4) An Example of Creating a Compressed RAM Disk
 -----------------------------------------------
@@ -151,12 +127,9 @@ f) Put the RAM disk image onto the flopp
 
 	dd if=/tmp/ram_image.gz of=/dev/fd0 bs=1k seek=400
 
-g) Use "rdev" to set the boot device, RAM disk offset, prompt flag, etc.
-   For prompt_ramdisk=1, load_ramdisk=1, ramdisk_start=400, one would
-   have 2^15 + 2^14 + 400 = 49552::
-
-	rdev /dev/fd0 /dev/fd0
-	rdev -r /dev/fd0 49552
+g) Make sure that you have already specified the boot information in
+   FDARGS and FDINITRD or that you use a bootloader to pass kernel
+   command line boot options to the kernel.
 
 That is it. You now have your boot/root compressed RAM disk floppy. Some
 users may wish to combine steps (d) and (f) by using a pipe.
@@ -167,11 +140,14 @@ users may wish to combine steps (d) and
 Changelog:
 ----------
 
+SEPT-2020 :
+
+                Removed usage of "rdev"
+
 10-22-04 :
 		Updated to reflect changes in command line options, remove
 		obsolete references, general cleanup.
 		James Nelson (james4765@gmail.com)
 
-
 12-95 :
 		Original Document
--- lnx-59-rc5.orig/Documentation/admin-guide/kernel-parameters.txt
+++ lnx-59-rc5/Documentation/admin-guide/kernel-parameters.txt
@@ -2441,8 +2441,7 @@
 
 	memblock=debug	[KNL] Enable memblock debug messages.
 
-	load_ramdisk=	[RAM] List of ramdisks to load from floppy
-			See Documentation/admin-guide/blockdev/ramdisk.rst.
+	load_ramdisk=	[RAM] [Deprecated]
 
 	lockd.nlm_grace_period=P  [NFS] Assign grace period.
 			Format: <integer>
@@ -3921,9 +3920,7 @@
 			Param: <number> - step/bucket size as a power of 2 for
 				statistical time based profiling.
 
-	prompt_ramdisk=	[RAM] List of RAM disks to prompt for floppy disk
-			before loading.
-			See Documentation/admin-guide/blockdev/ramdisk.rst.
+	prompt_ramdisk=	[RAM] [Deprecated]
 
 	prot_virt=	[S390] enable hosting protected virtual machines
 			isolated from the hypervisor (if hardware supports
@@ -3981,6 +3978,8 @@
 	ramdisk_size=	[RAM] Sizes of RAM disks in kilobytes
 			See Documentation/admin-guide/blockdev/ramdisk.rst.
 
+	ramdisk_start=	[RAM] RAM disk image start address
+
 	random.trust_cpu={on,off}
 			[KNL] Enable or disable trusting the use of the
 			CPU's random number generator (if available) to

Re: [RFC PATCH v2 1/2] Documentation/admin-guide: README & svga: remove use of "rdev"

[Martin Mareš]

Hello!

> "rdev" is considered antiquated, ancient, archaic, obsolete, deprecated
> {choose any or all}.
> 
> Remove use of "rdev" and "vidmode" (a symlink to rdev) in
> admin-guide/README.rst and admin-guide/svga.rst.

Acked-by: Martin Mares <mj@ucw.cz>

				Have a nice fortnight
-- 
Martin `MJ' Mareš                        <mj@ucw.cz>   http://mj.ucw.cz/
United Computer Wizards, Prague, Czech Republic, Europe, Earth, Universe
Press any key to quit or any other key to continue

Re: [RFC PATCH v2 0/2] Documentation/admin-guide: remove use of "rdev"

[Jonathan Corbet]

On Thu, 17 Sep 2020 18:56:38 -0700
Randy Dunlap <rdunlap@infradead.org> wrote:

> Remove mention of using "rdev" to set boot device, video mode,
> or ramdisk information for the booting kernel.
> 
> 
> Cc: Karel Zak <kzak@redhat.com>
> Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
> Cc: Jens Axboe <axboe@kernel.dk>
> Cc: linux-block@vger.kernel.org
> Cc: Alexander Viro <viro@zeniv.linux.org.uk>
> Cc: Martin Mares <mj@ucw.cz>
> Cc: linux-video@atrey.karlin.mff.cuni.cz
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> Cc: Jonathan Corbet <corbet@lwn.net>
> Cc: linux-doc@vger.kernel.org
> 
> 
>  [RFC PATCH 1/2] Documentation/admin-guide: README & svga: remove use of "rdev"
>  [RFC PATCH 2/2] Documentation/admin-guide: blockdev/ramdisk: remove use of "rdev"

Applied, thanks.

jon