[syslinux] USB boot problems on Gigabyte GA-M55Plus-S3G

Mattias Schlenker
Sun, 19 Jan 2014 19:39:15 -0000

Am 18.01.2014 04:30, schrieb Ronald F. Guilmette:
> The results were the same in both cases. In both cases, LessLinux
> Search & Rescue booted up and began a timed 10 second countdown, which
> I allowed it to finish in each case. After that, it started to do
> something... I'm not even sure what, exactly... and eventually froze
> up while displaying a progress bar, showing about 50% completion (of
> something) and the phrase "Starting dhcpcd".

It is an unstable build. DHCPCD got updated and might behave
differently. Its should continue after a very long time (five minutes or
so). If you are interested in booting LessLinux, press Tab when the menu
appears and add "dhcpcd" to the skipservices variable. But that's
off-topic here.

> For each of the two USB sticks I then powered the system off and
> rebooted again. Results were then identical to the first boot from
> each of the two sticks.

My intention was to find out, if this very special partitioning boots
correctly. Upon first boot you started an isohybrid thumbdrive with the
isohdpfx.bin boot record, the ISO was prepared with Thomas' xorriso.
After the first boot the drive gets partitioned to seven or eight
partitions with a GPT partition table with a legacy boot partition, an
UEFI boot partition and compat MBR. The boot sector in this case is
gptmbr.bin.

So far this setup really works best with legacy BIOS and modern UEFI. It
sometimes fails miserably with old broken EFI implementations.

To cut a log story short, we probably should write some advices for best
practices of creating bootable media. I got five:

 1. Never ever rely on partitioning or filesystems that a already on the
    user's thumb drives. These might use odd CHS geometries or drives
    may be flashed with a broken FS - partition and format using well
    proven tools
 2. If your system has to be bootable from USB and optical media try to
    deliver isohybrid images. Thomas and Mattias might help you with
    working around typical bugs in BIOS and UEFI implementations
 3. When converting a thumb drive to read only ISO9660 does not seem
    suitable, you might go with LessLinux' solution of converting the
    isohybrid drive to a partitioned layout with a large FAT32 partition
    at the start - this way even Windows can write to the drive. If
    windows doesn't matter just add one partition in the free space
    after the dd'ed ISO
 4. Check the media upon first boot. Too many too cheap thumb drives
    flip too many bits after a few dozen full writes.
 5. Move away from MBR/DOS, goto GPT, you'll be rewarded with reliable
    boot both on UEFI and on BIOS. You'll just break compatibility with
    Windows XP, but this is dead after April 8th anyway.

Regards,
Mattias

-- -
Mattias Schlenker - Redaktion + EDV-Beratung + Linux-CD/DVD-Konzepte
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