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SubjectRe: VGA PCI IO port reservations
On Fri, Nov 17, 2000 at 03:27:28PM -0500, Richard B. Johnson wrote:
> Then, you read the port as a WORD (16 bits). If nothing responds,
> you get the value of 0xffff. If somebody is responding, you will
> read something if it's enabled for writes by devices (reads by the CPU).

What guarantees you that:
1- No device will respond 0xffff for an address it decodes
2- No device will crap up on you simply because you've read one
particular address

If any of these if true for any device out there (I think I have one
in my computer that does the 1/ part in some cases), your code is
unsafe.

OG.

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