Re: [PATCH] Improve handling of "keep" in gfxpayload

[Colin Watson]

On Mon, Aug 10, 2009 at 05:27:25PM +0200, Robert Millan wrote:
> On Mon, Aug 10, 2009 at 02:05:15PM +0200, Vladimir 'phcoder' Serbinenko wrote:
> > What is the linux behaviour with 0x0F04? Does it just keep the mode?
> > What if the same mode is passed as a value? Does linux redoes the
> > modesetting? If 0x0F04 works ok I would prefer to always pass it when
> > kernel is booted in graphical mode. VESA mode numbers are an artifact
> > and when grub2 has its own graphical drivers it won't correspond to
> > anything.
> 
> I might be missing something, but AFAICT VESA mode numbers are only passed
> by the user in the "vga=" option.
> 
> There's also the `vid_mode' parameter in Linux header, but it's only used by
> legacy code, and with the 32-bit boot protocol Linux doesn't read it.

Hmm. You seem to be right, on investigation (I'd missed the fact that
the 32-bit boot protocol skips a whole bunch of initialisation code),
but in that case I'm thoroughly confused about why setting it made any
difference at all in my tests. Back to the drawing board, I guess.

(It's not actually quite true that vid_mode isn't used *at all* with the
32-bit boot protocol; it's still saved for use with ACPI sleep.)

> Does 0x0F04 really do something when used in combination with Linux' vesafb?

It seems to be 16-bit boot protocol only. I withdraw this patch for the
time being as I'm obviously confused.

-- 
Colin Watson                                       address@hidden