Re: /dev/mem and highmem

Nicolas George (
Thu, 6 Mar 2003 17:22:08 +0100

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Le tridi 13 vent=F4se, an CCXI, Nicolas George a =E9crit=A0:
> Is there any hope to have access to the highmem through /dev/mem, or a
> similar device? Or did I miss an already existing method?

Since nobody answered, I suppose that at least I did not miss something
obvious. Si I tried to write it.

What I understoud is that the way to access the byte at physical address
a is to kmap(mem_map[o >> PAGE_SHIFT]), and access at offet
o % PAGE_SHIFT (and then kunmap it). Perharps it is very ix86-centered.
Since it did not crash my PC, and it gave the same data as /dev/mem, I
think I was not totally wrong.

The code is available at <URL: >. The write
part is not yet done, but since it is very similar to read, it should be
really straightforward. Nevertheless I will wait a bit before trying it.


Nicolas George

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