Re: [Xen-devel] Unable to boot Xen 4.8 with iommu=0

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

. snip..
> >> > Given this commit is pretty old, I'm also curious why it's only reported
> >> > on 4.8. Tamas, did you succeed with iommu=0 pre 4.8, or 4.8 happens
> >> > to be the one upon which you first tried iommu=0 on a platform supporting
> >> > interrupt remapping?
> >>
> >> It just happens to be the one I tried. VT-d was spamming my console
> >> with faults like this:
> >>
> >> (XEN) [VT-D]DMAR:[DMA Write] Request device [0000:00:02.0] fault addr
> >> 277e28000, iommu reg = ffff82c000201000
> >> (XEN) [VT-D]DMAR: reason 05 - PTE Write access is not set
> >>
> >> So I figured I can just turn it off to clean up my console. I still
> >> don't know what these VT-d faults are about..
> >
> > What is the 0:02.0 device? Is it being passed in to your guest?
> 
> Nope, there is no pass-through to any guests. The device is:
> 
> 00:02.0 Display controller: Intel Corporation 2nd Generation Core
> Processor Family Integrated Graphics Controller (rev 09)

Let me guess, you have an SandyBridge motherboard and were using
Intel AMT?

I see those all the time on that box (and I think my Haswell
one too). The best I could narrow it down was that the card decided that
certain area should be in the RMRR regions. With Venu/Elen's patch
in (see 431685e8deb660976d8e986c41a647944e410c6c) you should be able
to provide an rmrr paramater to include these addresses.



I see those
> 
> Tamas

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