[syslinux] isohybrid boot from logical partition

Thomas Schmitt scdbackup at gmx.net
Thu Dec 29 02:10:22 PST 2016


do we have bystanders who can read x86 assembler code or know easy-to-grasp
reference docs?
(I left machine code programming when i gave up using my VIC-20.)

The MBR template isohdppx.bin stems from
with macro PARTITION_SUPPORT defined.

One can see the error message text in there:

	call	error
	.ascii	"isolinux.bin missing or corrupt.\r\n"

It seems to be reached only if the seen isolinux.bin does not bear the
magic number of isohybrid capable isolinux.bin.

        cmpl	$HYBRID_MAGIC,(isolinux_hybrid_signature)
        jne	bad_signature

Since we know that the isolinux.bin binary is well ok on other partitions,
i'd say that the MBR code does not load the right blocks from disk when
it wants to get isolinux.bin.

What happens if you use a partition editor to delete all MBR partitions
from the ISO image before you put it into the partition on disk ?
(An alternative to using a partition editor is
   dd if=/dev/zero conv=notrunc bs=1 count=64 seek=446 of=...iso

Have a nice day :)


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