[vfio-users] Is stolen memory wasted after IGD passed through into guest os?

[Acewind]

May I reduce the 128M to 8M in host BIOS, and set it to 128M by some
arguments when call seabios firmware?

Alex Williamson <alex.williamson at redhat.com> 于2018年9月25日周二 上午9:57写道：

> On Tue, 25 Sep 2018 09:44:24 +0800
> Acewind <acewind at gmail.com> wrote:
>
> > In my host os, command of ' lspci -v -s 00:02.0' will show:
> > Memory at e8000000 (64-bit, prefetchable) [size=128M]
> >
> > Is this 128M memory called 'stolen memory'?
>
> No, stolen memory is system memory dedicated to graphics use, it is not
> represented by a PCI BAR.
>
> > If this IGD device is passed through into guest os, will it be deserted
> and
> > wasted? Or mapped into and resused in guest os?
>
> PCI BARs are mapped to the VM.  SeaBIOS will attempt to allocate new
> stolen memory in the VM, so the host stolen memory is wasted, but it's
> not represented in a BAR.  Re-using the host stolen memory is difficult
> because it's not actually a resource associated with the device except
> through IGD usage and it's physical address space is immovable,
> creating holes in the VM address space at host specific addresses.
> Thanks,
>
> Alex
>
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