Re: [linux-fbdev] ISA memory space on != ia32

From: Bernd Harries (bha@gmx.de)
Date: Sat May 06 2000 - 16:46:29 EDT

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    Hi Geert,

    Some thoughts on your ISA ideas:

    Geert Uytterhoeven wrote:

    > On most other machines (ARM, MIPS, PPC), ISA memory
    > space is located somewhere else in PCI memory space.

    - What qualifies a 16 MB region to be called ISA space?
    - Can there only be 1 of these regions? 4 GB could hold 256 spaces a 16
    MB

    > However, there are still some problems left:
    >
    > 1. How to allocate ISA memory space?
    >
    > Some drivers do
    >
    > request_mem_region(0xA0000, 65535, ...)

    If start is a long int it it could easyly be 0x7F0A0000 or 0xFE0A0000.

    > request_isa_region(start,n,name)
    > release_isa_region(start,n)

    > check_isa_region(start,n,name)

    > What do you think?

    Perhaps an additional (enum) Parameter to select the ISA space?
    Or an additional function to globally select a 16 MB range as THE ISA
    space?

    What would it be like to access ISA IO space on archs which have mmapped
    IO?
    Some even have ISA IO inside 64K of _each_ ISA MEM space. 

    -- 
Bernd Harries

    bha@gmx.de           http://www.freeyellow.com/members/bharries
bha@nikocity.de       Tel. +49 421 809 7343 priv.  | MSB First!
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