Re: [Qemu-devel] [PATCH 0/3] Add BIOS splash image support

Laurent Vivier
2008-12-17T13:09:36Z

Le mercredi 17 décembre 2008 à 01:10 +0100, Carl-Daniel Hailfinger a
écrit :
> On 16.12.2008 22:51, Laurent Vivier wrote:
> > Le mardi 16 décembre 2008 à 22:46 +0200, Blue Swirl a écrit :
> >
> >> On 12/16/08, Anthony Liguori <anthony@codemonkey.ws> wrote:
> >>
> >>> Blue Swirl wrote:
> >>>
> >
> >
> >>>> The control channel may still be needed.
> >>>>
> >>>> Alternatively the BIOS could load the image and fade parameters from a
> >>>> new ROM or from the configuration device and draw it to screen. This
> >>>> would need some PNG support to BIOS, or that the image stored in raw
> >>>> form.
> >>>>
> >>>>
> >>>>
> >>> Yeah, having QEMU render to the VGA directly is a bit ugly. It would be
> >>> nicer if the BIOS actually rendered the image but I'm not sure I think we
> >>> should reject the patch just because it doesn't.
> >>>
> >> Actually this way the image can be in full color even if the emulated
> >> device was an EGA in text mode.
> >>
> >
> > And you can provide the image name on the command line, and complexity
> > is in Qemu, not in BIOS.
> >
>
> If one of the goals of QEMU is to be somewhat similar to hardware, this
> should be done in the BIOS.

A lot of things in Qemu are already not similar to hardware: virtio,
firmware configuration device, instruction timing...

> What happens if the BIOS provides a splash screen? Will it override the
> QEMU splash screen?

Yes. The BIOS asks Qemu to display the image... or not.

> > But in fact, my first idea was to read the image data from the
> > configuration device (which is always possible with LOGO_CMD_OFFSET),
> > but when I saw how it has been done in VirtualBox, I though it was a
> > good idea.
> >
>
> Modern x86 BIOSes read the splash screen from the BIOS ROM and the
> settings from NVRAM (sometimes the BIOS ROM is used for that as well by
> reflashing a sector of the ROM on every boot).

A BIOS, by definition, is not modern... ;-)
(Openfirmware is...)

Laurent
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