[vfio-users] "options vfio disable_vga=1"

[Alex Williamson]

On Sun, Nov 1, 2015 at 5:41 AM, Torbjorn Jansson <
torbjorn.jansson at mbox200.swipnet.se> wrote:

> Hi
>
> i guess this is a question for Alex Williamson.
> after reading part 3 of Alex vfio blog i have a question about the
> disablel_vga module option.
>
> in the blog there is one section that talks about "options vfio
> disable_vga=1"
> but if i do a modinfo on vfio i see no parameters at all but if i do a
> modinfo on vfio-pci i see  the parameter disable_vga.
>
> was this a typo in the blog?
>

Yes, fixed.


> if i use gfx cards with uefi only then this option can be considered a
> safety feature to prevent problems?
> or?


Depending on the Xorg driver used in the host, features like DRI may be
disabled if there are multiple VGA arbitration participants.  Using
disable_vga will allow any VGA devices bound to vfio-pci to opt-out of VGA
arbitration leaving fewer participants.  For instance, if you use Intel
graphics for the host and have a second graphics card for assignment,
supporting UEFI, disable_vga allows the Intel driver in the host to get
exclusive VGA access.
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