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From:   Ramana Radhakrishnan <ramana.gcc@googlemail.com>
Date:   Fri, 3 Aug 2018 10:37:29 +0100
Message-ID: <CAJA7tRahXGuPK=ktS5h86MZuV_o5cA3x1JbbyuwVspAHLKdP9g@mail.gmail.com>
Subject: Re: framebuffer corruption due to overlapping stp instructions on arm64
To:     Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc:     Florian Weimer <fweimer@redhat.com>,
        Thomas Petazzoni <thomas.petazzoni@free-electrons.com>,
        GNU C Library <libc-alpha@sourceware.org>,
        Andrew Pinski <pinskia@gmail.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Russell King <linux@armlinux.org.uk>,
        LKML <linux-kernel@vger.kernel.org>,
        Mikulas Patocka <mpatocka@redhat.com>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
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< snip>

> I guess the semantics of a framebuffer are not strictly defined, but
> the current reality is that it is expected to have memory semantics
> (by Linux/glibc)
>
> Matt is saying fundamental properties of the underlying interconnects
> (AMBA) make that impossible on ARM, but I'd like to understand better
> if that is universally the case, and whether such a system is still
> PCIe compliant.

I don't know that side of the architecture enough to make any
definitive statements.

>
> The discussion about whether memcpy() should rely on unaligned
> accesses, and whether you should use it on device memory is orthogonal
> to that, and not the heart of the matter IMO

Then maybe take libc-alpha off if it isn't relevant.

regards
Ramana