[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [RFC PATCH 8/8] Use Linux's PAT
On Tue, Dec 06, 2022 at 01:01:41PM -0500, Demi Marie Obenour wrote: > On Tue, Dec 06, 2022 at 11:38:03AM +0000, Andrew Cooper wrote: > > On 06/12/2022 04:33, Demi Marie Obenour wrote: > > > This is purely for testing, to see if it works around a bug in i915. It > > > is not intended to be merged. > > > > > > NOT-signed-off-by: DO NOT MERGE > > > > Following up on Marek's report on IRC/Matrix, you're saying that this > > change does actually fix screen corruption issues on AlderLake, and > > something on TigerLake too? > > Correct > > > If that is actually the case, then one of two things is happening. Either, > > > > 1) Drivers in Linux are bypassing the regular caching APIs, or > > This would not surprise me at all. > > > 2) The translation logic between Linux's idea of cacheability and Xen's > > PAT values is buggy. > > How could I check for this? See Andy's unit test idea on #xendevel: as a pretty simple "unit" test in dom0, it might be a good idea to have a module which watches the PTE in question, and cycles through various of the memremap_*() APIs and checks the raw PTE that gets written after Linux and Xen are done fighting with it -- Best Regards, Marek Marczykowski-Górecki Invisible Things Lab Attachment:
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