Re: [PATCH] Document Linux's memory barriers
From: H. Peter Anvin
Date: Thu Mar 09 2006 - 19:47:26 EST
Followup to: <28393.1141823992@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>
By author: David Howells <dhowells@xxxxxxxxxx>
In newsgroup: linux.dev.kernel
>
> However, on i386, for example, you've actually got at least two different I/O
> access domains, and I don't know how they impinge upon each other (IN/OUT vs
> MOV).
>
You do, but those aren't the ones.
What you have is instead MOVNT versus everything else. IN/OUT are
total sledgehammers, as they imply not only nonposted operation, but
the instruction implies wait for completion; this is required since
IN/OUT support emulation via SMI.
-hpa
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