Re: Accessing ISA board memory

From: FORT David ou popo (fort@irin.univ-nantes.fr)
Date: Thu Apr 06 2000 - 07:23:05 EST


michel wrote:

> Hello,
>
> Just to clarify ma question.
> I want to access to memory : 0xe00000-0x1000000 which is located on a ISA board.
> I don't want Linux to use these adresses, so i need a kind of system exclusion,
> perhaps on memory initialisation and I also need to know what virtual adresses
> correspond to theses physical adresses.
>
> In my driver, I already try to use char *ptr=0xc0e00000 but it isn't ok.

                                                        ^^^^^^^^^^^^^^^^^^^^^
 This can't work because memory is mapped virtually...... You must use a function to
access real
physical mem( i don't remember which one it is.......). When you write such ptr, it got in
kernel mem
which is forbidden for usual users.................

>
> On my board, these adresses are flash and I know what values I have to find
> (0x55 and 0xAA on the first bytes)
>
> every suggestion will be welcomed
> regards,
> Michel
>
> For the previous suggestions, il don't find any Isa_(read,write) in my system.
> Where are they ?
> My board is a ISA bord on a 80386 PC and the board memory is directly accessed
> from lynx with char * ptr=0xe00c8000 on the same PC, just by Hard disk
> switching.
>
>

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