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Date: Tue, 7 Jul 2015 12:27:43 +0200
Message-ID: <CAMuHMdX539+TRrZ+NtQNzJecVgT_Mc=CTZggixtcUg_GsFMjoQ@mail.gmail.com>
Subject: Re: [PATCH v5 2/6] arch: unify ioremap prototypes and macro aliases
From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: "Luis R. Rodriguez" <mcgrof@suse.com>, Christoph Hellwig <hch@lst.de>,
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On Tue, Jul 7, 2015 at 12:13 PM, Russell King - ARM Linux
<linux@arm.linux.org.uk> wrote:
> Another issue is... the use of memcpy()/memset() directly on memory
> returned from ioremap*().  The pmem driver does this.  This fails sparse
> checks.  However, years ago, x86 invented the memcpy_fromio()/memcpy_toio()
> memset_io() functions, which took a __iomem pointer (which /presumably/
> means they're supposed to operate on the memory associated with an
> ioremap'd region.)
>
> Should these functions always be used for mappings via ioremap*(), and
> the standard memcpy()/memset() be avoided?  To me, that sounds like a
> very good thing, because that gives us more control over the
> implementation of the functions used to access ioremap'd regions,
> and the arch can decide to prevent GCC inlining its own memset() or
> memcpy() code if desired.

Yes they should. Not doing that is a typical portability bug (works on x86,
not everywhere).

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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