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R5 MPU Background Region

ijahmad

I have a follow-up question from this.

I want to create a 4GB background region on R5 core. All I have to do is to fill following for region-0 in MPU?

starting address: 0

size: 2^32 = 0x100000000

Is anything else I need to do to declare a background region?

-ijaz

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  • +1 Arm Employee Badge in reply to ijahmad

    Register value of 0x3F => b0011_1111

    Dividing that into the fields:

    bit[0] = enable = b1 = Enabled
    bits[5:1] = RSize = b11111 = 31

    If you take a look at the description of RSize in the Armv7-A/R Architecture Reference Manual (Rev C.d, page 2720) it says "region size is 2^(N+1) bytes." (Where N is the value of the field)

    So 2^(31+1) = 4GB.

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  • +1 Arm Employee Badge in reply to ijahmad

    Register value of 0x3F => b0011_1111

    Dividing that into the fields:

    bit[0] = enable = b1 = Enabled
    bits[5:1] = RSize = b11111 = 31

    If you take a look at the description of RSize in the Armv7-A/R Architecture Reference Manual (Rev C.d, page 2720) it says "region size is 2^(N+1) bytes." (Where N is the value of the field)

    So 2^(31+1) = 4GB.

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