Re: qemu-xen-dir + PCI passthrough = BOOM

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Wed, Dec 18, 2013 at 04:13:05PM +0000, Ian Campbell wrote:
> On Wed, 2013-12-18 at 10:22 -0500, Konrad Rzeszutek Wilk wrote:
> > load_roms and bios_load are not set - so it wouldn't even do it.
> > It only does it for Bochs BIOS.
> 
> Right, this is deliberate.
> 
> For ROMBIOS (AKA BOchs BIOS) hvmloader loads the options roms. and I
> think ROMBIOS subsequently loads them.
> 
> For SeaBIOS it is the BIOS itself which both loads and executes the
> ROMS, which is why it is NULL in hvmloader.

Aha!
> 
> The SeaBIOS way is far more like how systems normally work and because
> the BIOS is in charge it can do a better job than splitting it between
> two entities.
> 
> Seems like perhaps I was mistaken about hvmloader+rombios not supporting
> loading from the ROM BAR of the device, it does seem to have some
> limited support for that (serial controllers and disk controllers only)
> 
> hvmloader+rombios does hardcode the VGA bios (rather than getting it
> from the emulated devices ROM bar), which is probably what I was
> thinking of, that's why people doing VGA passthrough with rombios need
> to grab the bios image and build it into hvmloader.

Right, which I hope to fix to make this work without this madness.
> 
> hvmloader+rombios also hardcodes the etherboot rom.
> 
> Ian.
>