Réf. : Re: Réf. : RE: mmap : please help !

scarayol at assystembrime.com scarayol at assystembrime.com
Fri Apr 15 00:37:53 EST 2005

Hello Jean-Christophe,

That's right, I verify all the useful parameters in my driver and
everything seems OK.
But, the real question is : if you use the /dev/mem (with open() and mmap
()), could you use, in the user space, the pointer returned by the mmap
function to access the physical memory or do you have to use read/write (on
the file descriptor) to access physical memory because i haven't the same
results according to the used method.
Thanks for 'od' but i haven't in my packages.


                    he Dubois            Pour :  scarayol at assystembrime.com                                                                   
                    <jdubois at mc.c        cc :    linuxppc-embedded at ozlabs.org                                                                 
                    om>                  Objet :      Re: Réf. : RE: mmap : please help !                                                     

Hello Sophie,

On Thu, 2005-04-14 at 11:38 +0200, scarayol at assystembrime.com wrote:
> Stéphane,
> thanks for your help.
> But I think that, except instruction eieio,  I do similar things. You use
> the virtual address returned by mmap but have you the same values if you
> use write/read(axs_mem_fd,...) instead of in_8/out_8.
> That is  my problem : I want to be sure that when I use the virtual
> returned by mmap, I access really to the physical memory mapped area.

As the /dev/map_mc is your custom driver it should be fairly easy for
you to check the parameters you pass to remap_page_range().

> Do you know a shell command in order to dump the memory and verify what I
> do ?

try "od"


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> Sophie CARAYOL
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