[SeaBIOS] [PATCH 3/6] qemu: add bochs-display support

[Gerd Hoffmann]

On Thu, May 31, 2018 at 10:44:55AM -0400, Kevin O'Connor wrote:
> On Thu, May 31, 2018 at 08:33:50AM +0200, Gerd Hoffmann wrote:
> > Use coreboot text mode emulation to also support the qemu bochs-display
> > device.  This is a new display device supporting simple linear
> > framebuffers, using the bochs register interface.  No support for legacy
> > vga (text modes, planar modes, cga modes, 8bpp palette modes all
> > dropped).  The bochs interface is compatible with the qemu stdvga.
> 
> Thanks.
> 
> Is "display bochs" the official name for this device?

It is "qemu -device bochs-display".

> I find the name
> a little confusing because it is both similar to regular "bochs" and
> similar to the "dispi" interface in the regular bochs driver.

Well, it actually is related.  In qemu 1.3 stdvga got a 32bit mmio bar,
and both vga and bochs dispi registers can be accessed using that
bar[1], in addition to the classic vga and bochs dispi io ports.

bochs-display has that mmio bar too, and it is the only way to program
the device.  Only the bochs dispi registers are available though as the
vga emulation is excluded.

> > +int
> > +bochs_display_setup(void)
> > +{
> > +    dprintf(1, "bochs-display: setup called\n");
> 
> Instead of adding this to cbvga.c could we add it to a new file?  (It
> and cbvga.c could still be linked together into the final vgabios
> binary.)

Sure.

cheers,
  Gerd

[1] details: https://git.qemu.org/?p=qemu.git;a=blob;f=docs/specs/standard-vga.txt;hb=HEAD