Messages in this thread | | | From | "H. Peter Anvin" <> | Subject | Re: memcpy_toio on i386 using byte writes even when n%2==0 | Date | Mon, 29 May 2006 00:38:05 -0700 (PDT) |
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Followup to: <44779358.9010703@shaw.ca> By author: Robert Hancock <hancockr@shaw.ca> In newsgroup: linux.dev.kernel > > It does seem a little bit less efficient, but I don't know think it's > necessarily a bug. There's no guarantee of what size writes will be used > with the memcpy_to/fromio functions. >
There are only a few semantics that make sense: fixed 8, 16, 32, or 64 bits, plus "optimal"; the latter to be used for anything that doesn't require a specific transfer size. Logically, an unqualified "memcpy_to/fromio" should be the optimal size (as few transfers as possible) -- we have a qualified "memcpy_to/fromio32" already, and 8- and 16-bit variants could/should be added.
However, having the unqualified version do byte transfers seems like a really bad idea.
-hpa
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