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CMEM /dev/cmem got lost after crashing user application

JT4589
Intellectual 330 points


I have a situation where I do not know the caused yet. The cmemkk.ko is loaded and working OK. But, for some reason when the userspace application got crashes, the device node for cmemkk (/dev/cmem) is disappeared. The userspace application is not directly connected to cmem, instead it uses the DMAI.

Any idea pointers why /dev/cmem is disappearing?.

Thanks,

John

  • 0
    TI__Mastermind 37340 points

    mmm, can you see /dev/cmem before the crash?  I assume you can, which is why you are aking this, but am less sure our software deliverables create such a device node, which is why I had to ask.

    That said, /dev/xxxx nodes represent a virtual file-system created during boot (and sometimes after boot) process; the only way I can think of a device node dissapearing are either manually removing it via script or command line, or maybe trashing the area of memory where this virtual file-system stores the device nodes,... in which case more than one device node may have been trashed...

  • 0 in reply to Juan Gonzales
    Intellectual 330 points

    The /dev/cmem is automatically created by udev upon loading the cmemk.ko.

    I used tmpfs for my /dev, I have only 87 device nodes and the size of tmpfs is only 1M.

    Do you think is there a problem using tmpfs for /dev and it's size?

    One more thing, when I used the cmemk.ko with debug enabled. Upon loading of the module, the /dev/cmem does not automatically created, instead I have to create it manually.

    Any explanation why the two version (release and debug) has a  different behavior?.

    john