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Original question:

LP-AM243:Secure Boot logs

LP-AM243: How to reload image files in case of authentication errors

Yukinobu Hasinoguti
Intellectual 300 points
Part Number: LP-AM243

Tool/software:

Hi,

If the RBL fails to load an image (SBL) with 0x0, an image (SBL) with 0x400000 will be loaded.
I would like to load a backup (read-only) image file into OSPI and boot that image if the SBL fails to authenticate the image file.




Q1) Is it possible, for example, to write an image file to the eFuse area? If so, can it be written with the OTP Keywriter?
　　
Q2) If writing to eFuse is not possible, is there any other way?

Regards,
Yukinobu

  • 0
    TI__Guru 70231 points

    Hello,

    1,2) The OTP area is not large enough to store an application image. So, the use case is not possible.

    Instead, the backup image could be flashed in the OSPI itself at some offset Y. If the SBL fails to load the original appimage from offset X, it could be modified to load the backup appimage from offset Y.

    BR, Prashant

  • 0 in reply to Prashant Shivhare
    Intellectual 300 points

    Hi Prashant,

    This OSPI is a non-secure area, not a secure area, correct?
    I would like to investigate how to recover the image file in case it has been tampered with,
    Does the LP-AM243x have a secure area that users can use as a backup area?

    Regards,
    Yukinobu

  • 0 in reply to Yukinobu Hasinoguti
    TI__Guru 70231 points

    Hi Yukinobu,

    Yukinobu Hasinoguti said:
    This OSPI is a non-secure area, not a secure area, correct?

    That is correct.

    Yukinobu Hasinoguti said:
    Does the LP-AM243x have a secure area that users can use as a backup area?

    There is no on-chip secure storage available large enough to store an application image. The best that can be done is to try booting multiple images until the authentication passes for a certain image. These multiple images may come from different interfaces. Like, you could first try booting backup image from OSPI. If this fails, you may try receiving an image over OTA and so on.

    Regards,

    Prashant