> 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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