[syslinux] isohybrid question

Thomas Schmitt scdbackup at gmx.net
Sun Mar 14 00:30:08 PST 2010


Hi,

the topic of LBA ambiguity in boot images needs
more examination. I confused patching the MBR
with patching isolinux.bin.

The original El-Torito/ISOLINUX code in libisofs
is not by me. So i have to learn better now.

I see the following occasions in libisofs
where LBAs are written into ISOLINUX objects:

- The El-Torito record gets the LBA of the
  boot catalog.
  (No address ambiguity involved.)

- The boot catalog gets the LBA of isolinux.bin.
  (Is that catalog involved in MBR booting ?)

- The boot image gets the LBA of the PVD at byte
  offset +8 and its own LBA at +12.

At least the third occasion might be a problem
with MBR booting.
Will the two addresses be used only relative to
/dev/sdb or might at some point the LBAs be
interpreted relative to /dev/sdb1 ?


Have a nice day :)

Thomas




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