Re: ARM with /proc/ioports?

Steven Woody <narkewoody@xxxxxxxxx> wrote:
there is an ARM board on my hand with a 2.4.x linux runing on it.
before i got the board, i heard, ARM architecture never use IO ports as
what x86 do, but in the /proc directory i still found a ioports file,
which contains,

d0000300-d000031f : eth0
d31002f8-d31002ff : serial
d31003f8-d31003ff : serial

what this mean? if ARM never use ioports, why the ioports file exists
in the OS?

They certainly have IO ports otherwise you'd never getting anything in or
out :-) But instead of having a IO address space separate to the memory
address space, they are accessing via portions of the memory address
space.

All the /proc/ioports is showing is the addresses used (in the one
address
space) by certain registered devices.

another confusion is, this board was equipped with PC/104 bus, and i
know PC/104 is actually ISA up to the term of architecture, but ISA
itself is architecture denpendent and tied with x86. my question is
that why PC/104 can be used on an ARM board? to accessing PC/104
resources, i believe the system need to issue seperated IO instructions
which is abvious impossible for ARM. am i right?

they fake it :-)

such a board would map part of its memory address range for PC104 IO use
and part for PC104 mem use, using glue logic to make sure the right
interface signals signals are generated to cmake it look like there were

separate IO and mem address spaces.

.

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