Failed to open /dev/mem from Anroid opencore framework

by Ling Wan » Fri, 07 Aug 2009 02:36:50 GMT

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We try to open "/dev/mem" from user space, within the opencore multimedia 
framework. The purpose is to allow access to hardware register of a 
peripheral, as well as map chunks of DMA safe memory between kernel and user 

 int fd = open("/dev/mem", O_RDONLY);

 While we can open and use "/dev/mem" under busybox (2.6.27 kernel and we have 
root permission), we got file descriptor -1 , when it's done from the opencore 
framework, where device driver is supposed to be added. We tried changing 777 
on "/dev/mem", no improvement.

What is the likely reason for that ? Is this due to Android's security
 restriction or some other reason? (We didn't enable SELinux option)

 And how do we solve it, or any alternative on sharing buffer between user / 
kernel space ? Some pointers / links would be great.




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