[Cbe-oss-dev] GCC inline memcpy() from local store causes bad page fault

Benjamin Herrenschmidt benh at kernel.crashing.org
Wed Mar 21 13:22:28 EST 2007

On Tue, 2007-03-20 at 22:19 -0400, David Edelsohn wrote:
> >>>>> Benjamin Herrenschmidt writes:
> Benjamin> This will also cause problems with userland. I though use of those
> Benjamin> string instructions was deprecated a long time ago for performance
> Benjamin> reasons anyway ... I'm surprised gcc still generates them.
> 	I'm not sure what you mean by "deprecated".  They are part of the
> PowerPC UISA.  If one is worried about code size, they are a good choice.
> -Os means optimize for size.

I missed the -Os bit. By deprecated, I meant shouldn't be generated by
default for performance reasons (though I suppose it's still acceptable
with -Os). Some newer freescale stuff don't implement them at all and
they are microcoded on pretty much everything new afaik.


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