[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Is: graphics corruption with 'xen: Support Xen pv-domains using PAT." Was:Re: [BUG] Characters on the screen are broken on Linux >= 3.19 with VT-d enabled
æ äï2015-06-16 æ 11:06 +0200ïJuergen Gross æåï > On 06/16/2015 10:55 AM, Ting-Wei Lan wrote: > > Juergen Gross æ èå2015å06æ16æ 12:30 åé: > > > On 06/15/2015 09:03 PM, Ting-Wei Lan wrote: > > > > æ äï2015-06-15 æ 14:55 -0400ïKonrad Rzeszutek Wilk æåï > > > > > On Sat, Jun 13, 2015 at 12:43:14AM +0800, Ting-Wei Lan wrote: > > > > > > When using Linux >= 3.19 as the dom0 kernel, characters on > > > > > > the > > > > > > screen become > > > > > > broken after the graphic driver is loaded. The commit that > > > > > > breaks > > > > > > it is > > > > > > (found by git bisect): > > > > > > > > > > > > > > > > > > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux > > > > > > .git/com > > > > > > mit/?id=47591df > > > > > > > > > > Lets CC Juergen > > > > > > > > > > > > > > > > > > Screenshot when the system run in single user mode: > > > > > > > > > > > > https://bugs.freedesktop.org/attachment.cgi?id=115079 > > > > > > Are those messages to be expected: > > > > > > (XEN) Scrubbing Free RAM on 1 nodes using 2 CPUs > > > (XEN) [VT-D]DMAR:[DMA Write] Request device [0000:00:02.0] fault > > > addr > > > b61eef000, iommu reg = ffff82c000203000 > > > (XEN) [VT-D]DMAR: reason 05 - PTE Write access is not set > > > (XEN) > > > ................................................................. > > > .done. > > > > > > I'm not familiar with VT-D internals, but seeing these messages > > > for the > > > video device during RAM scrubbing makes wonder if everything is > > > correct > > > regarding the VT-D and memory setup... > ... > > > > > > I still remember that there was a similar problem found two > > > > > > years > > > > > > ago on the > > > > > > same hardware with similar broken screen output and it also > > > > > > crashed > > > > > > after > > > > > > Xorg was started, but I cannot confirm that they are the > > > > > > same > > > > > > problems. I > > > > > > don't know whether error messages are simliar. > > > > > > > > > > > > The old problem happens on Linux 3.7 ~ 3.10 with VT-d > > > > > > enabled. It > > > > > > only > > > > > > happened when not using Xen, so I added 'intel_iommu=off' > > > > > > to Linux > > > > > > boot > > > > > > arguments to workaround it. > > > > > > Hmm, do you see any chance in finding the commit which made it > > > working > > > again? Perhaps there was some workaround for this hardware which > > > is > > > missing in Xen now... > > > > After some tests, I found the information I provided before was > > incorrect. It seems the problem happens on all Linux >= 3.7, > > including > > Linux 4.0.5, so the old problem was never fixed. Here are some > > 'dmesg | > > grep -i iommu' outputs. > > So a Xen-specific error is rather improbable, correct? But Linux provides 'intel_iommu=igfx_off' to workaround the problem. Does Xen provide similar things? > > I'd continue with sending the new information to the Intel graphics > team. I am going to reopen DRM/Intel bug 90037 on freedesktop bugzilla. > > > Juergen _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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