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Boot ROM Code for ARM Cortex A9 MP Core SoC

tushark tushark
Note: This was originally posted on 5th August 2011 at http://forums.arm.com

Hi,

I am working on ARM Cortex A9 MP Core SoC. As a part of software development, I need to understand how booting takes place in case ARM Cortex A9 considering the reset vector. I wanted to know more about the Boot ROM code which could be part of SoC. Can I get details / documentation / reference code about the Boot ROM code for ARM Cortex A9? Also I would like to know what are the steps involved in general booting sequence right from the RESET/Power ON till it loads the kernel.

Thanks & Regards,
TK
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  • Note: This was originally posted on 9th August 2011 at http://forums.arm.com


    Thanks Vaibhav for the information.
    I have one more question related to booting. As mentioned the execution of instructions after rest will start from address 0 or 0xFFFF0000. So If I am having NOR flash in my system, then do I need to map NOR flash to reset vector address? As NOR supports XIP, so all the initialization code should be placed in NOR at  address 0 or 0xFFFF0000 in assembly code. Is this understanding correct?

    Thanks,
    Tushark


    Yes, you need to map the Flash to reset vector address. Your NFlash(NOR/NAND) may need to be configured to fetch instruction at address 0. Regarding choosing the higher address or not, it is upto the memory map. The memory map address 0x00000000 is reserved for the vector table, a set of 32-bit words. On some processors the vector table can be optionally located at a higher address in memory (starting at the offset 0xffff0000). Operating systems such as Linux and Microsoft's embedded products can take advantage of this feature
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  • Note: This was originally posted on 9th August 2011 at http://forums.arm.com


    Thanks Vaibhav for the information.
    I have one more question related to booting. As mentioned the execution of instructions after rest will start from address 0 or 0xFFFF0000. So If I am having NOR flash in my system, then do I need to map NOR flash to reset vector address? As NOR supports XIP, so all the initialization code should be placed in NOR at  address 0 or 0xFFFF0000 in assembly code. Is this understanding correct?

    Thanks,
    Tushark


    Yes, you need to map the Flash to reset vector address. Your NFlash(NOR/NAND) may need to be configured to fetch instruction at address 0. Regarding choosing the higher address or not, it is upto the memory map. The memory map address 0x00000000 is reserved for the vector table, a set of 32-bit words. On some processors the vector table can be optionally located at a higher address in memory (starting at the offset 0xffff0000). Operating systems such as Linux and Microsoft's embedded products can take advantage of this feature
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