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Re: Grub2 almost does what I want

From: Jordan Uggla
Subject: Re: Grub2 almost does what I want
Date: Tue, 5 Feb 2013 15:04:46 -0800

On Sun, Feb 3, 2013 at 1:59 AM, Felix Miata <address@hidden> wrote:
> On 2013-02-03 04:24 (GMT-0500) Felix Miata composed:
>> On 2013-02-03 12:28 (GMT+0400) Andrey Borzenkov composed:
>>> 02 Feb 2013 16:04:18 -0500 Felix Miata composed:
>>>> 1-Get rid of the vga= is deprecated message. It has nothing to do with
>>>> Grub2
>>>> function.
>>> No quite. From Documentation/kernel-parameters.txt:
>>>                          This is actually a boot loader parameter; the
>>> value is
>>>                          passed to the kernel using a special protocol.
>> Either that doc is wrong, or it serves more than one purpose....
> On reflection I believe a third interpretation is the correct one, that is,
> "passed to the kernel" confirms that it is a kernel parameter, which the
> kernel can only acquire by virtue of its presence on cmdline, which makes it
> a "boot loader parameter". That is not to say it gets used for the boot
> loader's own function, because it isn't. The only thing the boot loader does
> with it is provide it to the kernel for the kernel's use. Consequently, the
> boot loader itself has no business complaining about its presence. It is not
> a valid purpose of a bootloader to report suitability or not of a particular
> kernel cmdline parameter to any particular kernel, even if one was known to
> be deprecated, or even unsupported, when the boot loader was built.

Your interpretation is completely incorrect. The kernel's
documentation means exactly what it says, vga= is a parameter
interpreted by the bootloader, which then switches to a given video
mode before handing off to the kernel, and passes information about
this mode via other means. The linux kernel does not interpret the
vga= parameter, and if grub simply ignored it (but still passed it on
as part of the linux cmdline) you would not get the desired effect.
Since this is a parameter interpreted by the bootloader rather than
the kernel it really doesn't make sense for it to be in the linux
cmdline at all. That is why grub instead uses GRUB_GFXPAYLOAD (or
$gfxpayload when working directly with a grub.cfg) as the means of
telling grub what mode it should hand off to the kernel.
GRUB_GFXPAYLOAD and $gfxpayload also take simple resolutions in
readable strings like "1024x768x32" rather than arcane VESA mode
numbers, making it even more appropriate to use. vga= is deprecated
but (for now) is still handled by grub for backwards compatibility, it
should not be used in new installations.

Jordan Uggla (Jordan_U on

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