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Re: framebuffer corruption due to overlapping stp instructions on arm64
- From: Mikulas Patocka <mpatocka at redhat dot com>
- To: Ard Biesheuvel <ard dot biesheuvel at linaro dot org>
- Cc: Florian Weimer <fweimer at redhat dot com>, Andrew Pinski <pinskia at gmail dot com>, Richard Earnshaw <Richard dot Earnshaw at arm dot com>, Ramana Radhakrishnan <ramana dot gcc at googlemail dot com>, Thomas Petazzoni <thomas dot petazzoni at free-electrons dot com>, GNU C Library <libc-alpha at sourceware dot org>, Catalin Marinas <catalin dot marinas at arm dot com>, Will Deacon <will dot deacon at arm dot com>, Russell King <linux at armlinux dot org dot uk>, LKML <linux-kernel at vger dot kernel dot org>, linux-arm-kernel <linux-arm-kernel at lists dot infradead dot org>
- Date: Tue, 7 Aug 2018 10:14:13 -0400 (EDT)
- Subject: Re: framebuffer corruption due to overlapping stp instructions on arm64
- References: <alpine.LRH.2.02.1808021242320.31834@file01.intranet.prod.int.rdu2.redhat.com> <alpine.LRH.2.02.1808032046540.24748@file01.intranet.prod.int.rdu2.redhat.com> <CA+=Sn1=6F-fGLmXE0VqQHTqTCUKUT=Fz29mMT7349SPFisbZ9A@mail.gmail.com> <alpine.LRH.2.02.1808040611070.23762@file01.intranet.prod.int.rdu2.redhat.com> <fd2cae87-b2df-d8ef-8836-e6cbf8c5f851@redhat.com> <alpine.LRH.2.02.1808060325110.3756@file01.intranet.prod.int.rdu2.redhat.com> <CAKv+Gu_y6La77sWOSROrwfRy65jrFVYVvRZt+ewNheYhdhHCkQ@mail.gmail.com> <alpine.LRH.2.02.1808060626060.2986@file01.intranet.prod.int.rdu2.redhat.com> <CAKv+Gu87YqLM=FFZ6V8rHhuhskDdsBUuXFpqNKVbXWqdnuNEyA@mail.gmail.com> <alpine.LRH.2.02.1808060639200.2986@file01.intranet.prod.int.rdu2.redhat.com> <CAKv+Gu8HyHX8qjg1qHV2M9Re+RGQJigjdAFVC_yR4niGkk2ikA@mail.gmail.com> <alpine.LRH.2.02.1808060700070.10220@file01.intranet.prod.int.rdu2.redhat.com> <CAKv+Gu8384LZwL898wJ8BKjmJNzvd+-cSFUp4X4OpfmRDCP4Ng@mail.gmail.com>
On Mon, 6 Aug 2018, Ard Biesheuvel wrote:
> No that works fine for me. VDPAU acceleration works as well, but it
> depends on your chromium build whether it can actually use it, I
> think? In any case, mplayer can use vdpau to play 1080p h264 without
> breaking a sweat on this system.
>
> Note that the VDPAU driver also relies on memory semantics, i.e., it
> may use DC ZVA (zero cacheline) instructions which are not permitted
> on device mappings. This is probably just glibc's memset() being
> invoked, but I remember hitting this on another PCIe-impaired arm64
> system with Synopsys PCIe IP
DC ZVA can be disabled with the SCTRL_EL1.DZE bit, so that neither kernel
nor userspace will use it. If the mapping didn't support unaligned writes,
it would be worse.
Mikulas