[vfio-users] PCI-Stub still needed for now?

[Blank Field]

It is possible to bind needed devices to vfio-pci on the kernel command
line now.
Alex himself, afair, uses e3-1245v3, it has IGD and the ACS is almost fine
there.
Usually only processor root ports have ACS and isolation between devices,
so they get grouped into separate groups.
If there is no isolation between devices, they end up in one group: you
must patch your kernel and hope it helps or bind every device to vfio-pci.
The problem is - we don't know if the new motherboard+chipset+cpu provides
the needed isolation, it is only guaranteed on E5 series of CPUs, which are
expensive as hell.

Intel graphics don't like multiple vga arbitration participants: you can
work around this by the following methods:
1. Patch i915 driver.
2. Use OVMF and disable vga on the discrete card via vfio-pci module option.
3. Use full UEFI on the host and make i915 forget about VGA and it's
arbitration.
On Sep 20, 2015 5:29 PM, "Eddie Yen" <missile0407 at gmail.com> wrote:

> Hello, guys, long time no see.
> I have a long time that following updates about VFIO.
>
> As I read AW's blog, I found that there is no pci-stub needed for now.
> Looks like vfio-pci can get video card for 'greedy' graphic driver.
> Is that true?
>
> Because I'm still using the old method to launch VM with X79 platform.
> (Using pci-stub and QEMU command.)
> But I may got a case that may using IGD as host video output to run KVM.
> May use Z97 or new Z170 as platform.
>
> According to blog, if using the mainstream platform, it's better to use E3
> series.
> Because E3 series had ACS module inside.
> And I know E3 had some models that included IGD.
> So it nay not have IOMMU Group problem? Or it depends on motherboard
> design?
>
>
> Apologize my bad English again.
>
> AKSN74
>
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