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Device driver module MMAP issue from user space application

Question asked by johnp on Feb 6, 2012
Latest reply on Feb 8, 2012 by Aaronwu

When I mmap from a user space application for a specific device mmap returns an address not associated with the device or the memory allocated by the device.  After adding debug to the mmap routine in the module it seems as though the mmap from the module's file operations is never called.  open, custom ioctl's work fine. 

 

I run into the same problem when use the sample module example provided on:

 

https://docs.blackfin.uclinux.org/doku.php?id=mmap#mmap_system_call

 

This simple applications thinks it mmap'ed properly, but when I add debug to the mmap routine for this module, it never shows up.

 

Has anyone occurred a similar proper or have any thoughts on what the issue might be?

 

I am using uClinux-dist-2010R1-RC2.

 

Also my custom device module works as expected on the standard Linux machines.

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