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Subject: Re: [Qemu-devel] [PATCH] set vidmode in linux kernel header when
	boot x86 using qemu bootloader
From: Mark McLoughlin <markmc@redhat.com>
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Date: Tue, 26 May 2009 15:26:48 +0100
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To: joy zhao <yanhwizhao@gmail.com>
Cc: qemu-devel@nongnu.org

On Tue, 2009-05-26 at 18:22 +0800, joy zhao wrote:
> hi,
> I made a patch to have qemu parse vga field in kernel command line and
> set the vid_mode field of real-mode kernel header.
> This patch is necessary because vga is one of the special command line
> options that should be parsed in bootloader, as in linux kernel
> Documentation/x86/i386/boot.txt. After bootloader write the passed vga
> value into the vid_mode field of linux real-mode kernel header, this
> vid_mode will be handled by linux/x86/boot/video.c in linux kernel to
> select vesa graphics mode, and only in this mode can vesafb be
> registered(in vesafb_probe()).
> So, if we decide to launch linux directly from qemu command line as
> "qemu -kernel ... -initrd... -append "..." ", (use qemu bootloader)
> and use vesafb as framebuffer driver, this patch to qemu is required,
> otherwise, the screen should just blank since the vesafb fails to
> register itself.

FWIW, I agree we do need this - see also:

  https://bugzilla.redhat.com/501935
    qemu-kvm -kernel should parse "vga=" cmdline option

Cheers,
Mark.