Messages in this thread | | | Date | Thu, 14 Mar 2002 13:24:19 -0800 (PST) | From | Linus Torvalds <> | Subject | Re: IO delay, port 0x80, and BIOS POST codes |
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On Thu, 14 Mar 2002, John Heil wrote: > > No, the better/correct port is 0xED which removes the conflict.
Port ED is fine for a BIOS, which (by definition) knows what the motherboard devices are, and thus knows that ED cannot be used by anything.
But it _is_ an unused port, and that's exactly the kind of thing that might be used sometime in the future. Remember the port 22/23 brouhaha with Cyrix using it for their stuff, and later Intel getting into the fray too?
So the fact that ED works doesn't mean that _stays_ working.
The fact that 80 is the post code register means that it is fairly likely to _stay_ that way, without any ugly surprises.
Now, if there is something _else_ than just the fact that it is unused that makes ED a good choice in the future too, that might be worth looking into (like NT using it for the same purpose as Linux does port 80),
Linus
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