Hi David,

On Sun, 2011-02-27 at 17:38 +0000, David Brown wrote:

Per the gcc manual:

    If your assembler instructions access memory in an unpredictable
   fashion, add `memory' to the list of clobbered registers.  This will
   cause GCC to not keep memory values cached in registers across the
   assembler instruction and not optimize stores or loads to that
   memory.  You will also want to add the `volatile' keyword if the
   memory affected is not listed in the inputs or outputs of the `asm',
   as the `memory' clobber does not count as a side-effect of the `asm'.
   If you know how large the accessed memory is, you can add it as input
   or output but if this is not known, you should add `memory'.  As an
   example, if you access ten bytes of a string, you can use a memory
   input like:

Right, so if you neglected to check the output from the smc block then
it would be a candidate for removal even with a memory clobber. Now I
see why you want a volatile in there!

For what it's worth:

Acked-by: Will Deacon <redacted>

Will