how to read/write registers of CPU or Device from user space

Hollis Blanchard hollisb at
Tue Jan 13 07:14:43 EST 2004

On Jan 12, 2004, at 9:31 AM, Hollis Blanchard wrote:

> On Jan 12, 2004, at 7:48 AM, Muhammad Sarwar wrote:
>> From user space access, use mmap.
> (Note that it won't work for RAM, but that's not what you're trying to
> do anyways.)

I misunderstood something here; you can in fact remap RAM via /dev/mem.
This mapping will be done with the VM_RESERVED flag set, which was not
acceptable in the context I heard it discussed, but I guess is ok
generally speaking.

Hollis Blanchard
IBM Linux Technology Center

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