Re: [PATCH] x86_64: fix problems due to use of "outb" to port 80on some AMD64x2 laptops, etc.

[H. Peter Anvin]

Alan Cox wrote:
> > > i dont think this should matter: old systems that truly _need_ the ISA 
> > > delay will be slow enough to not trip up. (nor are they really affected 
> > > by these early delays - the delays were more for crappy ISA devices that 
> > > get initialized later down, when the delay loop is already calibrated)
> > 8253 (DMAC) and 8254 (PIT) have been reported in earlier versions of the 
> > thread. By Alan, I believe.
>
> They've been seen to be problems up to PII era machines. I'm not aware of
> any newer than that with this problem. We also don't need to touch the
> DMAC that early anyway that I can see - just the PIT.
>
> In fact if we have a fast processor we have a TSC and APIC so we don't
> need the PIT ?

Well, the TSC may be unstable and the APIC may be disabled.

	-hpa
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