[OpenBIOS] [PATCH] Add support for accessing the LinuxBIOS CMOS settings from Open Firmware
Maciej W. Rozycki
macro at linux-mips.org
Fri Oct 12 15:10:33 CEST 2007
On Fri, 12 Oct 2007, Torsten Duwe wrote:
> The MC146818 is ISA legacy, so dev/isa has my vote. Pulling out any
> PC-specific or firmware-dependent semantics would be perfect, though.
Well, to be exact, MC146818 and anything in the 0x00-0xff port I/O space
is motherboard, not ISA. ISA port I/O space is 0x0100-0xffff in theory
(address lines up to the bit #15 are driven on I/O cycles) and 0x100-0x3ff
in reality (many cards did not decode address lines from the bit #10
And, unlike ISA (in most cases), it is still there in x86-based
PC/AT-class systems, usually in the south bridge. OTOH, the 0x100-0x3ff
stuff migrated to the so called LPC bus and typically got reduced to some
super-I/O chip hanging off there.
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