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SubjectRe: [PATCH] x86 bitops.h commentary on instruction reordering
On Fri, 6 Aug 2004, Marcelo Tosatti wrote:

> Yes correct. *mb() usually imply barrier().
>
> About the flush, each architecture defines its own instruction for doing so,
> PowerPC has "sync" and "isync" instructions (to flush the whole cache and instruction
> cache respectively), MIPS has "sync" and so on..

JFTR, in the absence of an external write-back buffer (which some
processors have) the MIPS "sync" instruction has exactly the semantics of
mb(). There is no MIPS instruction to perform writeback, invalidation,
etc. operations on whole caches -- such operations can only be performed
in the kernel mode on a line-by-line basis and are model-specific, though
some standardisation exists.

Maciej
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