Re: RFC: outb 0x80 in inb_p, outb_p harmful on some modern AMD64with MCP51 laptops
From: H. Peter Anvin
Date: Mon Dec 10 2007 - 20:52:28 EST
David Newall wrote:
Exactly. You think it's 2us, but the documentation doesn't say. The _p
functions are generic inasmuch as they provide an unspecified delay.
Drivers which work across platforms, and which use _p, therefore have
different delays on different platforms. Should the length of the delay
be unimportant? I wouldn't have thought so. If it is important, does
that mean that such drivers are buggy on some platforms?
That the _p delay is different across platforms is actually to be
expected, since it pretty much amounts to a platform delay. And yes, if
it is used as a specific walltime delay that has nothing to do with the
bus architecture of the system then I would classify that as a driver bug.
-hpa
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