Messages in this thread | | | Date | Fri, 18 Dec 1998 12:56:35 +0100 (MET) | From | "Maciej W. Rozycki" <> | Subject | Re: proper ioport space allocation |
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On Fri, 18 Dec 1998, Kurt Garloff wrote:
> On Thu, Dec 17, 1998 at 06:04:12PM -0600, Bob McElrath wrote: > > > Does anyone know if the PCI-ISA bridge blocks addresses with something other > > than zero in the high word from reaching the ISA devices? (I assume PCI I/O > > ports are 32-bits) > > PCI I/O is 32 bits (or even 64 on some architectures) and I think all > addresses are forwarded to PCI bus, but the ones with the high word == 0 > also to ISA. Maybe there are optimizations to prevent the low addresses to > be seen (and block?) the PCI bus ... I don't know.
PCI I/O address space is 16-bit. 32-bit I/O addresses may work if a single PCI bus is present but they cannot cross PCI-PCI bridges.
-- + Maciej W. Rozycki, Technical University of Gdansk, Poland + +--------------------------------------------------------------+ + e-mail: macro@ds2.pg.gda.pl, PGP key available +
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