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SubjectRe: [PATCH] x86_64: fix problems due to use of "outb" to port 80 on some AMD64x2 laptops, etc.
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On 14-12-07 19:02, H. Peter Anvin wrote:

> I believe this will suffer from the issue that was raised: this will use
> udelay() long before loop calibration (and no, we can't just "be
> conservative" since there is no "conservative" value we can use.)
>
> Worse, I suspect that at least the PIT, which may need to be used for
> udelay calibration, is one of the devices that may be affected. I have
> seen the Verilog for a contemporary chipset, and it can only access the
> PIT once per microsecond -- this actually has to do with the definition
> of the PIT; some of the PIT operations are ill-defined if allowed at a
> higher frequency than the PIT clock.

Was reported before indeed:

http://linux.derkeiler.com/Mailing-Lists/Kernel/2003-09/5764.html

Rene.



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