Messages in this thread |  | | Date | Fri, 17 Nov 2000 20:20:09 -0500 | From | Olivier Galibert <> | Subject | Re: VGA PCI IO port reservations |
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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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