Re: [Qemu-devel] [PATCH] hw/display: Add basic ATI VGA emulation

[Gerd Hoffmann <kraxel@redhat.com>]

  Hi,

> > Which linux driver is this?
> 
> Those in linux/drivers/video/fbdev/aty/. This ati-vga model defaults to Rage
> 128 Pro (what PoweMac3,1 has, device id 0x5046) which is handled by the
> aty128fb driver under Linux. MIPS fulong2e has Mobility Radeon M6 (RV100,
> device id 0x5159) that you can also use as -device ati-vga,device_id=0x5159
> which is driven by radeonfb under Linux.

So it could be tested with linux guests on x86 too I guess?
Can the radeon drm driver handle the devices too?

I'd also use model=<name> instead of device_id=... to switch between
different devices.

> > If linux has a native driver it might make sense to also enable it on
> > x86.  Makes testing easier.
> 
> Yes it could work on all archs under Linux but I've only enabled it on the
> two I've tried. It could be added instead to the same place where vga is
> added in pci.mak if you like.

Makes sense IMHO.

> > You can add the driver to default_list[] in vl.c, then you don't need
> > -vga none to remove the default vga when adding -device ati-vga.
> 
> I could do that but since it's a bit unfinished (lacks advanced features
> such as video overlay, 3D accel, command FIFO, etc.) and only a basic
> implementation at the moment to work with Linux framebuffer that doesn't use
> these features I thought it might be a godd idea to make it a bit harder to
> access yet to avoid problem of someone trying it with a Windows guest with
> drivers from ATI which probably will result in bad picture. But it's up to
> you to decide if you want to add it to -vga option from the start or have it
> as optional device and only add to -vga when it's more fully implemented and
> tested.

It's not about "-vga ati".  This is about adding ati-vga to the list of
display devices, so qemu will not try to add a vga automatically in case
it finds "-device ati-vga" on the command line.  That way "qemu -device
ati-vga" will work fine, without "-vga none".

Adding -vga ati indeed only makes sense once the implementation is more
complete.

cheers,
  Gerd