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i.MX7: eMMC boot failure fallback to other boot partition?

Question asked by Petri on May 26, 2017
Latest reply on May 31, 2017 by Petri



We are planning on using eMMC 5 for booting our i.MX7 custom board.  The software is field-upgradable, but must be able to fall back to the previous version if the upgrade is somehow nonfunctional.


What's the best way to implement this functionality?

  • I see there's PERSIST_SECONDARY_BOOT (IMX7DRM section, but this seems tricky to use, as it is persistent.  Is there a way to enable the secondary boot behavior *once*, and have it revert for the next boot?
  • MMC has boot0 and boot1 partitions, and the ROM seems to read the ext_csd registers to determine which to boot from (per "Figure 6-32. Expansion Device (MMC) Boot Flow (2 of 6)").  However, as above, this is a persistent setting in the eMMC, right? (I actually can't find confirmation of this anywhere.)


I'd love to hear some guidance as to the most fail-proof booting strategy for software upgrades.  Thanks!