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My newbie question is on request_mem_region() used to define RAM-mapped area. Assuming the call returns success, does it mean the memory region becomes available for read/write access for every process in the system? (Here I'm talking about the system without VM, i.e. we can directly address the memory). If yes, what are the ways to control the access to the area?

Thanks, Mark.

Mark
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  • Possible duplicate: http://stackoverflow.com/questions/7682422/what-does-request-mem-region-actually-do-and-when-it-is-needed/7738534#7738534 – sawdust Feb 08 '13 at 00:50
  • Do you want that region to be accessible for some kernel driver, for userspace, or both? – CL. Feb 08 '13 at 15:46

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request_mem_region() does not define a RAM-mapped area, it just requests one. In other words, if the call succeeds, nobody else will be able to request the same region.

This is just a mechanism to prevent multiple drivers from trying to grab the same device, it doesn't help with actually accessing that memory region. You still have to remap that region.

CL.
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