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AM1808 AISgen

Terry16065
Expert 1185 points

Other Parts Discussed in Thread: AM1808

Customer is using AISgen to generate AIS-signed U-Boot images for an AM1808-based single-board computer. Currently they are using AM1808 rev 2.0 silicon revisions, and generating AIS images for this target (D800K006). Will they be able to run images generated for older silicon revisions on newer targets? I.e., if they were to generate an image for silicon rev. 2.0, can they always expect to be able to run this image on newer silicon (rev 2.1 and later)?

  • 0
    TI__Guru** 116840 points

    Terry,

    Short answer here is No, they cannot use the same AIS image with a newer revision. Silicon rev 2.0 to Silicon rev 2.1 has a significant update in the ROM code, please view Appendex E of Bootloader appNote to view all the changes. The ROM ID on silicon rev 2.1 is D800K008. If they migrate to the newer revision, they will need to generate a AIS boot image using the new ROM ID.

    Regards,

    Rahul

  • 0 in reply to Rahul Prabhu
    Prodigy 120 points

    Does this mean that going forward that we should assume that an AIS image built for Rev. 2.1 will not work for Rev. 2.2 and beyond?  We cannot assume backward compatibility?

    Thanks,

    John K.

  • 0 in reply to John Klaffenbach
    TI__Guru** 116840 points

    John,

    My response earlier corresponded to update from 2.0 to 2.1. Weather an AIS image can be reused on a newer version of the silicon depends on the ROM ID as you may have noticed in the AISGen tool. while creating the boot image, you are expected to select the ROM ID on your device. We have documented the ROM revision on silicon revisions in the bootloader App note Appendix E. The ROM ID on both rev 2.1 and rev2.2 is D800K008 so you can reuse the boot image on the two versions you have mentioned. It is always recommended to check the ROM ID using the Debug.gel file provided in the bootloader and serial flashing utilities before flashing the boot image.

    In most cases when the update in the ROM code doesn`t significantly change system level settings the boot images can be reused, but incase of 1.0 to 2.0 migration we will definitely recommend, recreating the boot image.

    Regards,

    Rahul

  • 0 in reply to Rahul Prabhu
    TI__Guru** 116840 points

    John,

    I would like to clarify my earlier comment as I just looked over the bootloader code to confirm this. There isn’t any check that the ROM makes to validate that an AIS boot image is created for a specific revision, so in general a user can assume that the old boot image that was created for an earlier revision can be used with the next revision. However in case of 2.0 to 2.1 there were significant changes to the NAND boot and the DDR configure function and hence the recommendation to create a new image.

    Regards,

    Rahul