Re: [Xen-devel] [BUG] After upgrade to Xen 4.12.0 iommu=no-igfx

[Roman Shaposhnik <roman@xxxxxxxxxx>]

On Wed, Jul 31, 2019 at 1:43 AM Roger Pau Monné <roger.pau@xxxxxxxxxx> wrote:
>
> On Wed, Jul 31, 2019 at 10:36:31AM +0200, Roger Pau Monné wrote:
> > On Tue, Jul 30, 2019 at 10:55:24AM -0700, Roman Shaposhnik wrote:
> > > Sorry -- got a bit distracted yesterday. Attached is the log with only
> > > your latest patch attached. Interestingly enough the box booted fine
> > > without screen artifacts. So I guess we're getting closer...
> > >
> > > Thanks for all the help!
> >
> > That's quite weird, there's no functional changes between the
> > previous patches and this one, the only difference is that this patch
> > has more verbose output.
> >
> > Are you sure you didn't have any local patches on top of Xen that
> > could explain this difference in behaviour?
>
> FWIW, can you please try the plain patch again:
>
> https://lists.xenproject.org/archives/html/xen-devel/2019-07/msg01547.html
>
> And report back?
>
> I would like to get this committed ASAP if it does fix your issue.

I'd like to say that it did -- but I tried it again just now and it
still garbled screen and tons of:

(XEN) printk: 26665 messages suppressed.
(XEN) [VT-D]DMAR:[DMA Read] Request device [0000:00:02.0] fault addr
8e14c000, iommu reg = ffff82c0008de000

I'm very much confused by what's going on, but it seems that's the
case -- adding those debug print statements make the issue go away

Here are the patches that are being applied:
   NOT WORKING:
https://github.com/rvs/eve/blob/xen-bug/pkg/xen/01-iommu-mappings.patch

   WORKING: 
https://github.com/rvs/eve/blob/a1291fcd4e669df2a63285afb5e8b4841f45c1c8/pkg/xen/01-iommu-mappings.patch

At this point I'm really not sure what's going on.

Thanks,
Roman.

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