From mboxrd@z Thu Jan 1 00:00:00 1970 From: pavel@ucw.cz (Pavel Machek) Date: Sun, 5 Aug 2018 23:51:50 +0200 Subject: framebuffer corruption due to overlapping stp instructions on arm64 In-Reply-To: References: <9acdacdb-3bd5-b71a-3003-e48132ee1371@redhat.com> <11f9185a-7f71-83df-3a57-0a0ae9c1f934@arm.com> Message-ID: <20180805215150.GB1862@amd> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi! > > Can you run the test program on x86 using the similar framebuffer > > setup? Does doing two writes (one aligned and one unaligned but > > overlapping with previous one) cause the same issue? I suspect it > > does, then using memcpy for frame buffers is wrong. I'm pretty sure it will work ok on x86. > Overlapping unaligned writes work on x86 - they have to, because of > backward compatibility. It is not that easy. 8086s (and similar) did not have MTRRs and PATs either. Overlapping unaligned writes _on main memory_, _with normal MTRR settings_ certainly work ok on x86. Chances is memory type can be configured to work similar way on your ARM/PCIe case? > 8086, 80286 and 80386 didn't have any cache at all. 386s had cache (but not on die). Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 181 bytes Desc: Digital signature URL: