ARM with /proc/ioports? - Embedded

This is a discussion on ARM with /proc/ioports? - Embedded ; 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 ...

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Thread: ARM with /proc/ioports?

  1. ARM with /proc/ioports?

    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?

    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?

    thanks.
    -
    woody


  2. Re: ARM with /proc/ioports?

    Steven Woody 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.


  3. Re: ARM with /proc/ioports?


    Jim Jackson wrote:
    > Steven Woody 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.
    >


    thank you. another question is, there is neither a 'pci' file under the
    /proc nor a lspci command in the system, does this mean the board
    doesn't equip a pci bus?

    > > 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.


    1, what measn PC104 IO use and PC104 mem use?
    2, can a program use inb() outb() when it running on the board to
    access extended PC104 peripherals?

    thank you.


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