2008-11-26 01:39:27     Memory Protection

Document created by Aaronwu Employee on Aug 8, 2013
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2008-11-26 01:39:27     Memory Protection


Message: 65813   




I have used a couple of uclinux based blackfin products:


bluetechnix core modules, http://tinyboards.com/rainbow2006/site/blackfin_family/__core_modules/__cm-bf537e/313/cm-bf537e.aspx


SRV1: http://www.surveyor.com/blackfin/#blackfin2


Now SRV code seems to access the memory mapped registers directly from user-space. The MPU seems to be turned off. When I try to do the same on the blue-technix, the code crashes and gives a dump. I have been trying to figure where the MPU could be turned off but I ave not been able to figure it out.


Is there any way I can turn off the MPU and recompile the kernel without the MPU? Also the kernel disttribution for both SRV and bluetechnix is the same. Hence the SRV must be doing this by some configuration file only and not hacking the kernel directly right? If it is some config file then is it available on menuconfig??






2008-11-26 02:17:02     Re: Memory Protection

Mike Frysinger (UNITED STATES)

Message: 65814   


however you think the SRV is working, it is not.  it is literally impossible to allow userspace to directly access MMRs.  this is enforced in hardware and cannot be changed.