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34A bit of info on the "Trailer" data bytes at end of image

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  • paulbart1234
    Aug 9, 2004
      Not too much info, but I noticed the string "eRcOmM" as part of the
      16-byte "Trailer" at the end of the Flash image (end of 8MBytes):

      00 01 00 00 23 24 90 F7 65 52 63 4F 6D 4D 00 6D ....#$÷eRcOmM.m

      I did a case-sensitive search for it, and found the following
      strings in the Redboot code:

      copy kernel code from flash to RAM
      copy ramdisk file from flash to RAM
      have eRcOmM
      no node address
      run kernel
      push button
      not have eRcOmM

      (For those who don't know, "Redboot" is a boot loader (from Redhat)
      that can start up in 'serial terminal' mode. You can give it a boot
      script to load images from Flash to RAM, load images from the
      network, etc)

      From the above strings, I'd *guess* that startup code looks for
      the "eRcOmM" string @ the end of the Flash, possibly in order to
      determine whether/not it's got valid code in it to run (as opposed
      to startin up in Redboot serial terminal mode).

      The other hex bytes in the "Trailer" may (for example) contain the
      load address of the kernel image, and a checksum/CRC of it. I have
      no idea.

      BTW, a case-*insensitive* search for "eRcOmM" finds more occurrences
      of it in the Redboot section of Flash ("ErCoMm"). I'm not sure what
      it's used for.

      - Paulb
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