[virt-tools-list] vga passthrough

Cole Robinson crobinso at redhat.com
Wed Oct 17 17:34:45 UTC 2012


On 09/27/2012 07:22 AM, Martin Wolf wrote:
> hello,
> 
> im using kvm with virt-manager and i really like the interface you provide.
> but i would like to know if there is a way to supply a romfile to a passed through
> device like shown here.
> 
> http://www.linux-kvm.org/page/VGA_device_assignment
> *VBIOS ROM access*
> To re-run the POST procedures of the assigned adapter inside the guest, the
> proper VBIOS ROM image has to be used. However, when passing through the
> primary adapter of the host, Linux provides only access to the shadowed
> version of the VBIOS which may differ from the pre-POST version (due to
> modification applied during POST). This has be been observed with NVDIA Quadro
> adapters. A workaround is to retrieve the VBIOS from the adapter while it is
> in secondary mode and use this saved image (-device
> pci-assign,...,romfile=...). But even that may fail, either due to problems of
> the host chipset or BIOS (host kernel complains about unmappable ROM BAR).
> 
> thank you in advance
> 

virt-manager doesn't support that option. You can set it with libvirt though,
use virsh edit to add something like this to your <hostdev> block:

<rom file='/etc/fake/bootrom.bin'/>

How to use virsh edit:

http://wiki.libvirt.org/page/FAQ#What_is_the_.27virsh_edit.27_command_and_how_do_I_use_it.3F


- Cole




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