Messages in this thread | | | Subject | Re: IO delay, port 0x80, and BIOS POST codes | From | (Eric W. Biederman) | Date | 15 Mar 2002 04:30:44 -0700 |
| |
Linus Torvalds <torvalds@transmeta.com> writes:
> 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),
Does the logic outb_p uses continue to work if you have a PCI post card (possibly on the motherboard). And an ISA device?
Systems without ISA slots but with ISA or LPC devices onboard must use a PCI post card so I have trouble believing that outb_b and friends really work as expected....
Eric - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |