On Thu, 27 Mar 2003, Edgardo Hames wrote:
> El Mar 25 Mar 2003 13:21, Richard B. Johnson escribió:
>
> > On Tue, 25 Mar 2003, Edgardo Hames wrote:
> > > Hi everybody. I'm trying to write a simple device driver to read and
> > > write memory at addresses beween 0xc0000 and 0x100000, but when I try to
> > > load the module I get the following error:
> >
> > Check out ioremap(). Although the addresses you show are already
> > mapped, you need to access them with the "cookie" returned from
> > ioremap().
>
> I tried ioremap'ing the addresses and now it doesn't oops, but I keep reading
> 255 no matter what I write to that address. I have no device at that
> addresses, but what I'm trying to do is reading and writing to that memory
> area like it was a file.
>
> Thanks,
> Edgardo
Do you know that there are RAM where you are reading/writing?
If there is nothing there, your read will have all bits set.
Also, the cookie returned from ioremap() is __not__ a pointer!
You need to read/write using the appropriate macros. See
../linux-n.n/include/asm/io.h for details.
Cheers,
Dick Johnson
Penguin : Linux version 2.4.20 on an i686 machine (797.90 BogoMips).
Why is the government concerned about the lunatic fringe? Think about it.
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This archive was generated by hypermail 2b29 : Mon Mar 31 2003 - 22:00:28 EST