Re: [Qemu-devel] Cirrus bugs vs endian: how two bugs cancel each other out

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Mon, 2012-08-06 at 16:02 +0200, Gerd Hoffmann wrote:
> 
> A vbe rom isn't a big deal.  You probably want support the 0x01CE and
> 0x01CF ports (on x86) so the vgabios running in real mode can easily
> reach the bochs interface registers without a protected mode round
> trip
> for mmio access.
> 
> I *think* for seavgabios this needs just a rebuild with an approximate
> configuration (see roms/Makefile and roms/config.vga.*).  The code
> already checks whenever bar 0 is actually memory not mmio because this
> is needed for the vmware vga too. 

My current layout is

 BAR 0 : virtio (including commands to access all the registers)

 BAR 1 : MMIO regs (there just in case, they might come in handy
                    to make the DRM driver more oops-resistant,
                    but they are unused by my WIP code)

 BAR 2 : framebuffer for scanout

I have legacy VGA & Bochs VBE ports wired up as well (it's trivial), did
a quick vgabios change and that works, I haven't looked at seabios yet
but it looks trivial enough.

I have a port of SLOF that uses the virtio channel to configure the
linear mode (using the VBE regs via the virtio tunnel) and that works.

I've started putting together a DRM +fb driver for the guest side, but
that's not done yet.

I've also done a trivial 2D blitter mostly for use by the fb and/or SLOF
but I haven't wired it up yet.

Cheers,
Ben.