[syslinux] Failure to boot isohybrid image from USB stick

[Thomas Schmitt]

Hi,

i did not succeed to get my test computer (Asus A7V8X-X
of 2004) to boot from an isohybrid image.
I tried 
  http://www.tux.org/pub/people/kent-robotti/looplinux/rip/RIPLinux-7.0-non-X.iso
which is obviously isohybrid enabled.

The system has a "Promise Ultra 133 TX2" IDE controller
which supercedes the mainboard BIOS.
To make the system react on the USB stick i set boot
option "USB ZIP" on both BIOSes. (Unclear whether the
mainboard BIOS is in effect at all after the IDE
controller takes over.)
None of the BIOSes offered me any other USB boot
option (like "USB HDD" or so).

The outcome with RIPLinux-7.0-non-X.iso :

 to USB via RIP's mkusb.sh as FAT:    boots
 to USB via dd of=/dev/sdb bs=1M
  unprocessed RIP .iso image:         stalls
  by syslinux-3.72/util/isohybrid:    stalls
  by xorriso-0.2.9:                   stalls
  
"stall" looks like what one usually experiences by
a non-bootable floppy in the drive at boot time:
a blinking text cursor and no boot progress.

Any proposals what to do in order to find out
what is wrong with isohybrid MBRs on that machine ?

-------------------------------------------------

The development version 0.2.9 of xorriso is now
able to perform the operation of
syslinux-3.72/util/isohybrid on the fly while
generating the ISO image.
By default an MBR is generated if util/isohybrid
would not abort. A missing magic number in
isolinux.bin prevents MBR generation but does not
prevent the ISO image generation with El Torito.

The MBR feature is ready for multi-session on
overwriteable media (USB stick, disk file, DVD+RW,
BR-RE, ...). On sequential media (CD-R[W], DVD-R,
DVD+R) the MBR can only be written by the first
session.

-------------------------------------------------

MBR generation has been tested against a mock-up of
the perl script isohybrid with various sets of
ISO size and isolinux.bin LBA.
Except the random $id all bytes did match.

It has also been tested with RIPLinux-7.0-non-X.iso.
xorriso took the files from the mounted RIP image
and added its own El Torito and MBR.
I compared the MBR produced by xorriso and the MBR
which was produced by syslinux-3.72/util/isohybrid
for the same image (after its end padding was removed).
Again, only $id differed.

-------------------------------------------------

Interested testers please download:
  http://scdbackup.sourceforge.net/xorriso-0.2.9.tar.gz

Example of writing a prepared file tree under /mnt
as ISO image directly onto USB stick at /dev/sdb:

  xorriso -as mkisofs -o /dev/sdb \
     -b boot/isolinux/isolinux.bin -c boot/isolinux/boot.cat \
     -no-emul-boot -boot-load-size 4 -boot-info-table \
     /mnt

resp.:

  xorriso -outdev stdio:/dev/sdb \
          -blank as_needed \
          -boot_image isolinux dir=/boot/isolinux \
          -map /mnt /

The MBR feature may be disabled by adding option
  -as mkisofs ... isolinux_mbr=off ...
resp.
  -boot_image isolinux isohybrid=off

Default is mode "auto". Mode "on" would prevent the
ISO image generation if no isohybrid magic number can
be found in isolinux.bin.


Have a nice day :)

Thomas