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OTP Keywriter build workflow

Walter Stoll
Intellectual 490 points
Part Number: MCU-PLUS-SDK-AM243X
Other Parts Discussed in Thread: SYSCONFIG

Tool/software:

Hi team

We are implementing secure boot on a AM64X based custom board. We downloaded the OTP Keywriter artifacts from here https://www.ti.com/secureresources/AM64X-HS-RESTRICTED-SW and tried to build an example Keywriter image based on the instructions we found in the "AM64X_AM243X OTP Keywriter User Guide". This worked well so far. However, we have some questions regarding the build workflow:

1) Building a Keywriter image requires a number of different tools (AM243x MCU+ SDK, CCS, SysConfig, TI ARM CLANG) with defined versions. We build our images by means of Yocto and would like to build the Keywriter with Yocto also. Is there a Yocto workflow available ?

2) We noted, that CCS does not actually take part in the build. What is CCS used for ? Did we miss some important steps ?

3) We need to adapt some Keywriter sources according to the requirements of our custom board. For maintenance reasons we think it is not a good idea to simply modify the sbl_keywriter sources. Is there a porting guide or some best practices available that give us some hints about how to do this in a maintainable way ?

Regards

Walter

  • +1
    TI__Guru 71071 points

    Hello,

    A1) No. The OTP Keywriter works with the MCU+ SDK only which doesn't have any Yocto build environment.

    A2) The CCS is used at the following point to convert the ELF to BIN.

    ❯ grep -C1 CCS_PATH -- sbl_keywriter/am64x-evm/r5fss0-0_nortos/ti-arm-clang/makefile

OBJCOPY=$(CCS_PATH)/utils/tiobj2bin/tiobj2bin

--
$(BOOTIMAGE_BIN_NAME): $(OUTNAME)
        $(OBJCOPY) $(OUTNAME) $(BOOTIMAGE_BIN_NAME) $(CGT_TI_ARM_CLANG_PATH)/bin/tiarmofd $(CGT_TI_ARM_CLANG_PATH)/bin/tiarmhex $(CCS_PATH)/utils/tiobj2bin/mkhex4bin

    A3) You may intialize the installed Keywriter with Git to track the modifications. For any new releases, you may evaluate the diff & accordingly decide if you wish to migrate.

    Regards,

    Prashant