[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
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 æåïOn 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=47591dfLets CC JuergenScreenshot when the system run in single user mode: https://bugs.freedesktop.org/attachment.cgi?id=115079Are 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? I'd continue with sending the new information to the Intel graphics team. Juergen _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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