Sophie CARAYOL wrote: >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.
The read/write method is a heavy weight method, while the pointer returned by mmap is light and very efficient way in user-space, and It just works(tm). Have you made sure the read/write is bypassing caching/speculative mode? Can some timing issues explain the difference? Are you reading/writing the right number of bytes? Can you check both methods on a ReadOnly hardware register, with a known value to be read? >Thanks for 'od' but i haven't in my packages. Anything else from dd with hexdump to your own built peek & poke? What about mempoke from Conor McLoughlin? http://ozlabs.org/pipermail/linuxppc-embedded/2004-October/015871.html Regards, -- Stephane
