Re: RFC: outb 0x80 in inb_p, outb_p harmful on some modern AMD64 with MCP51 laptops

H. Peter Anvin
2007-12-11T01:52:24Z

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