[vfio-users] Intel igd passthrough / rom

[nicolas prochazka]

Hello,
I'm facing of a strange phenomenon, if someone can explain me :

I'm starting a vm ( Windows guest) with intel igd passthrough :

<hostdev mode='subsystem' type='pci' managed='yes'>
                        <source>
                         <address domain='0x0000' bus='0x00'
slot='0x02' function='0x0'/>
                        </source>
                        <address type='pci' domain='0x0000' bus='0x00'
slot='0x02' function='0x0'/>
                </hostdev>

It"s working well, the Vm is booting, display a standard Vga boot (
windows logo ) , then after sometime windows detect intel card and
change resolution.

Now, i've dump igd rom (  /sys/devices/pci0000:00/0000:00:02.0/rom )
and i'm starting the  Vm with :

      <hostdev mode='subsystem' type='pci' managed='yes'>
                        <source>
                                <address domain='0x0000' bus='0x00'
slot='0x02' function='0x0'/>
                        </source>
                        <address type='pci' domain='0x0000' bus='0x00'
slot='0x02' function='0x0'/>

<rom file='/data/romIgd'/>

                </hostdev>

it's working but, the Vm is booting, then the screen seems to be pass
into standby mode, then after sometime windows detect intel card and
screen is ok.

So my question is :  When no rom file is provide, qemu load a standard
vga bios before ? then load rom ?

Regards,
Nicolas Prochazka