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

[H. Peter Anvin]

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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/