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OMAP L137 and L138 boot-loader

Arthur Cartier
Intellectual 410 points
Other Parts Discussed in Thread: OMAPL138

Hello,

I'm trying to develop a boot-loader for an OMAP L137 or L138, and I would like to clarify few points :

  • The TI primary boot-loader and AIS script interpreter is located in the ROM of the ARM core and there is no way to modify it or to replace it by my boot-loader ?
  • The TI primary boot-loader and AIS script interpreter is using all the ROM of the ARM core and my boot-loader cannot be placed in this ROM next to the TI boot-loader ?
  • If I use an AIS script to load my secondary  boot-loader will always load it to the Shared memory starting at the address 0x80000000 ?

Cordially

Arthur CARTIER

  • 0
    TI__Guru** 116170 points

    Arthur,

    Both OMAPL138 and OMAPL137 are different in the boot sequence. OMAPL137 is a DSP boot device wherein the AIS script parsing runs on the ROM is run on the DSP which is the first to power up on reset. OMAPL138 is a ARM boot device where the AIS script parsing resides in the ROM and will be executed on the ARM. The ROM code on both the devices is fixed and there is no option to write user boot loader along side the TI bootloader. However you can use the ROM code only to initialize the device PLL, PINMUX and SDRAM settings and then run a secondary bootloader from RAM that can essentially implement the changes required in the boot process. The secondary bootloader doesn`t require the AIS script interpreter implemented in it as essentially ROM code exits after parsing the initial boot image and loading the secondary bootloader in RAM.

    The location of the secondary bootloader doesn`t have to be in shared memory. you can place the secondary bootloader in exernal memory, L2 or L3 memory. This is controlled using the linker command file or the memory configuration file you use while building the secondary bootloader.

    Regards,

    Rahul