[syslinux] Gigabyte motherboards and Syslinux

[Rodney Beede]

On Sun, Sep 21, 2008 at 2:48 PM, H. Peter Anvin <hpa at zytor.com> wrote:
> Rodney Beede wrote:
>> I read the mailing list archive about Gigabyte motherboards not working
>> with USB booting ("[syslinux] Gigabyte recent bios & syslinux extlinux
>> trow USB-IDE bridges or pendrives", 16 Aug 2006).
>>
>> I have a Gigabyte GA-MA790GP-DS4H motherboard that I tried to boot in
>> USB-HDD mode with a PNY boot pen.  I installed System Rescue CD on it.
>>
>> It would appear that Gigabyte still doesn't support booting from USB
>> with Syslinux.  I did boot BartPE (Windows based boot loader) from the
>> same usb key without issues on the board.  There are no bios updates for
>> my motherboard.
>>
>
> It would be *extremely* weird if every Gigabyte motherboard had
> problems.  Most likely it is limited to a relatively small set of
> motherboards.
>
> The fact that you can boot BartPE, however, is illustrative; it does
> seem to mean that there is something that can be used as a fulcrum to
> make these things boot.  The question is how to find it.  I'll have to
> think about possible attack avenues.
>
> I presume there is no USB-ZIP mode.
>
>        -hpa
>


There are the following boot modes possible with this motherboard:

Floppy
LS120
Hard Disk
CDROM
ZIP
USB-FDD
USB-ZIP
USB-CDROM
USB-HDD
Legacy LAN
TSSTcorp CDDVDW (my specific sata dvd drive)


I tried all 4 USB-xxx modes.  All of them gave me the same "Boot Error" message.

Perhaps something in the NTLDR boot loader on the BartPE usb key is
also hard coded by the motherboard bios?  One possible attack avenue
may be to load syslinux via the NT boot loader as a menu option.  It
has an Award bios if that helps.

I found the usbkeys.txt that discusses modifying the partition
structure on the usb device so it more closely mimics a USB-ZIP
device.  I believe BartPE uses this method of partition creation which
may explain why it works.  I'll try doing that, booting in USB-ZIP,
and see if it works.

Thanks for looking at it.

Rodney Beede