Messages in this thread |  | | Date | Tue, 6 Nov 2001 20:39:12 +0100 (MET) | From | "Maciej W. Rozycki" <> | Subject | Re: ioport range of 8259 aka pic1 |
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On Tue, 6 Nov 2001, Randy.Dunlap wrote:
> The Intel chipset specs say that PIC1 uses: > (all hex:) 20-21, 24-25, 28-29, 2c-2d, 30-31, 34-35, 38-39, 3c-3d. > > Some of the older chipset specs say that all of these other than > 20-21 are just aliases of 20-21 (like the 440MX spec). > Later specs don't say this (as in all of the 800-model ICH0/ICH2 > specs).
These are chipset implementation details (i.e. address decoder's shortcomings) only. An 8259A only uses two I/O ports; in PC/AT systems, these are 0x20, 0x21 and 0xa0, 0xa1 for the two PICs, respectively. Since the 0x00-0xff range is assigned to motherboard devices, there is no problem with leaving aliases free -- they are never used by Linux. You still need to verify your extra devices are really present there.
-- + Maciej W. Rozycki, Technical University of Gdansk, Poland + +--------------------------------------------------------------+ + e-mail: macro@ds2.pg.gda.pl, PGP key available +
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