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    SubjectRe: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code
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    From: Scott Wood <scottwood@freescale.com>
    Date: Tue, 20 May 2008 17:43:58 -0500

    > David Miller wrote:
    > > The __volatile__ in the asm construct disallows movement of the
    > > inline asm relative to statements surrounding it.
    > >
    > > The only reason barrier() in kernel.h needs a memory clobber is
    > > because of a bug in ancient versions of gcc. In fact, I think
    > > that memory clobber might even be removable.
    >
    > Current versions of GCC seem quite happy to move non-asm memory accesses
    > around a volatile asm without a memory clobber; see the test Trent posted.

    Indeed, and even the GCC manual is clear about this.


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