Re: some question about wmb in mips

[Ralf Baechle <ralf@linux-mips.org>]

On Mon, Jun 28, 2010 at 12:16:06AM +0800, loody wrote:

> Dear all:
> AFAIK, wmb in mips is implemented by calling sync,
> wmb->fast_wmb->__sync, which makes sure Loads and stores executed
> before the SYNC are completed before loads
> and stores after the SYNC can start
> But will this instruction write the cache back too?

No.

> take usb example, it will call this maco before it let host processing
> the commands on dram, so I wondering whether sync will write the cache
> back to memory.

SYNC is for memory consistency, not coherency.

  Ralf