Hi,
inspection of the ISOs is not needed any more, since we now know
that your algorithm expects "powerpc" bootable ISOs, not those
for "ppc64el".
Nevertheless, as we are at it:
Here is the output of xorriso:
...
System area summary: MBR CHRP cyl-align-off
ISO image size/512 : 9162480
...
MBR partition table: N Status Type Start Blocks
MBR partition : 1 0x80 0x96 0 9162480
Drive current: -indev '/root/debian-8.1.0-ppc64el-DVD-1.iso'
That's CHRP without HFS.
Preparer Id : XORRISO-1.3.6 2014.04.08.180000, LIBISOBURN-1.3.6,
LIBISOFS-1.3.6, LIBBURN-1.3.6
Dear packagers: Version 1.4.0 is out :)
The debian-7.8.0-powerpc-netinst.iso yields:
System area summary: MBR CHRP cyl-align-off APM
ISO image size/512 : 529812
...
MBR partition table: N Status Type Start Blocks
MBR partition : 1 0x80 0x96 0 529212
APM : N Info
APM block size : 512
APM gap fillers : 0
APM partition name : 1 Debian 7.8.0 ppc 1
APM partition type : 1 Apple_HFS
APM start and size : 1 16 529196
Drive current: -indev 'debian-7.8.0-powerpc-netinst.iso'
...
App Id : GENISOIMAGE ISO 9660/HFS FILESYSTEM CREATOR (C) 1993 E.YOUNGDALE (C) 1997-2006 J.PEARSON/J.SCHILLING (C) 2006-2007 CDRKIT TEAM
The difference between ISO size and partition size probably
comes from genisoimage default padding of 300 KiB.
I think this is not fully CHRP compliant.
Shrug.
Have a nice day :)
Thomas