Messages in this thread | | | Date | Sat, 15 Dec 2007 12:25:20 -0800 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH] x86_64: fix problems due to use of "outb" to port 80 on some AMD64x2 laptops, etc. |
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Rene Herman wrote: > > It's really going to have to be a known _un_used register and (the write > direction of) port 0x80 is used exactly for that reason. Port 0xed is a > known "alternate diagnostic port" used by Phoenix BIOSes at least but > Peter Anvin reported trouble with that one -- probably for the outb > direction but assuming that means something was in fact responding, we'd > have the same timing problem. >
Yes, for the outbound direction.
> I believe we have two "good" options: > > 1) port 0xed was tested by the current reporter and found to be safe > (and provide slow enough timing). If DMI based quirk hacks are > available soon enough we can switch 0x80 to 0xed based on it. Are they?
DMI is just a data structure parked in memory, so it should at least be theoretically possible to get to it.
-hpa
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