[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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