Problem Changing LOCAL_MEM_LOCAL_ADRS on PPC750GX Board - VxWorks

This is a discussion on Problem Changing LOCAL_MEM_LOCAL_ADRS on PPC750GX Board - VxWorks ; I'm trying to relocate VxWorks and the application code to the upper half of memory. This is in preparation to get the second PPC750GX running on an dual PPC 750GX board. But, I can't change LOCAL_MEM_LOCAL_ADRS without the board hanging ...

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Thread: Problem Changing LOCAL_MEM_LOCAL_ADRS on PPC750GX Board

  1. Problem Changing LOCAL_MEM_LOCAL_ADRS on PPC750GX Board

    I'm trying to relocate VxWorks and the application code to the upper
    half of memory. This is in preparation to get the second PPC750GX
    running on an dual PPC 750GX board. But, I can't change
    LOCAL_MEM_LOCAL_ADRS without the board hanging up. I don't get any
    serial output at all...

    I'm not trying to relocate the vector table. I was told moving the
    LOCAL_MEM_LOCAL_ADRS should resolve vector table addresses. When we
    eventually turn on the second processor and run in dual processor mode
    modifications to the table will be needed to notify the handler where
    the code was executing prior to the interrupt...

    I'm booting from vxWorks.st_rom from flash. I've also modified
    RAM_LOW_ADRS and RAM_HIGH_ADRS to above address specified by
    LOCAL_MEM_LOCAL_ADRS. Also, I've modified LOCAL_MEM_SIZE to specify
    the amount of memory above LOCAL_MEM_LOCAL_ADRS (actually I've tried
    pretty much every combination of these define values).

    Here are some of the specifics about the board:
    Two PPC750GX processors
    MV64460 System Controller
    256MB DDR SDRAM
    32MB 32-bit wide Flash
    Two 100BASE-TX Ethernet ports
    Two 16550 compatible serial ports

    Any insight would be appreciated!

    Robert


  2. Re: Problem Changing LOCAL_MEM_LOCAL_ADRS on PPC750GX Board

    RAM_LOW_ADRS RAM_HIGH_ADRS must be right in makefile and project.

    LOCAL_MEM_LOCAL_ADRS LOCAL_MEME_ZIZE USER_SAVE STACK_SAVE must be
    right


  3. Re: Problem Changing LOCAL_MEM_LOCAL_ADRS on PPC750GX Board

    I finally figured it out. When I changed LOCAL_MEM_LOCAL_ADRS this
    affected the sysPhysMemDesc[] table. This define is used to provide
    MMU coverage for memory from the beginning of memory (where the PPC
    vector table is) to the top of memory. Moving this value left the
    lower area of memory unmapped.

    Actually the ICE led me to a bcopy() that was trying to setup these
    vectors. This is where the system would hang. By putting entries in
    the sysBatDesc[] table for instruction and data accesses to lower
    memory this solved the problem.

    Now I can put the VxWorks image wherever I want.

    Robert


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