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

From: Bernd Harries (bha@gmx.de)
Date: Sat May 06 2000 - 15:46:29 EST

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!
harries@stn-atlas.de       +49 421 457 3966 offi.  | Linux-m68k
bernd@linux-m68k.org      8.48'21" E  52.48'52" N  | Medusa T40

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