[PATCH v5 2/6] arch: unify ioremap prototypes and macro aliases

On Tue, Jul 7, 2015 at 12:13 PM, Russell King - ARM Linux
[off-list ref] 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 at 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