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Change the replacement stratege of cache

xiaochang yu
Note: This was originally posted on 6th August 2010 at http://forums.arm.com

Hi,all.
For the design of system, I want to change the repalcement stratege of cache from random replacement to predictable replacement. So I need to change the bit[14] in control register(c1) of cp15 from 0 to 1. But the property of this bit is secure modify only. Could tell me how could I modify it? The arm system  i used is arm11 with wince6.0.
Thanks.
  • Note: This was originally posted on 18th August 2010 at http://forums.arm.com

    My ARM is ARM1176JFZ-S. So can you tell the system calls WINCE6.0 provide? Thanks.
  • Arm Employee Badge
    Note: This was originally posted on 18th August 2010 at http://forums.arm.com

    My ARM is ARM1176JFZ-S. So can you tell the system calls WINCE6.0 provide? Thanks.


    You could try changing it at boot-time in the bootstrap code, I doubt the OS code tries to set the cache replacement policy.

    Failing that you could try to implement some for of priviledged mode driver (something like a a character driver should do the trick), but letting user-space apps change settings like this is usually deemed a "bad idea", so perhaps it is something you could change in the board-support-package code which enables the cache in the first place.
  • Arm Employee Badge
    Note: This was originally posted on 9th August 2010 at http://forums.arm.com

    Which ARM11 are you using?  Only the ARM1176JFZ-S supports TrustZone, and has the Secure access only restriction.

    Assuming it is an 1176...  Unless the design is actively using TrustZone, it is probably running in the Secure world already.  You will also need to be in a privileged mode - which means its under the control of the OS.  So the question becomes what system calls does WinCE 6.0 provide to let you manipulate it.