USB Boot Enabler

Since a few(?) releases, you can simply "dd" your openSUSE ISO-file onto an USB stick and boot from that, which is pretty cool and which I use a lot.
But recently, I came across a machine that simply does not boot from the USB stick. No matter what settings I tried in the BIOS - no boot. I believe it will only boot from internal hdd, internal CDROM or internal floppy and via PXE.
Instead of just burning the ISO onto a CD and using that (that would have been too easy, wouldn't it?), i booted an old rescue system I had still lying around on CD and found out, that the BIOS actually does enumerate the USB stick on boot, at least it shows up in /sys/firmware/edd and /dev/disk/by-id/edd-int13_dev81, so I wondered how to boot from it.

The answer was easy: Just copy what the openSUSE CD does for "boot from local harddrive". It's actually very easy (/tmp/x is the root directory for the ISO)

mkdir -p /tmp/x/isolinux
cp /usr/share/syslinux/isolinux.bin /tmp/x/isolinux/

Then create a /tmp/x/isolinux/isolinux.cfg file, with the following content:

say ***********************************************
say seife's USB boot enabler
say enter 0,1,2,3 for disk 0-3
say disk 0 is usually your local built-in harddrive
say disk 1 is probably your USB stick
say ***********************************************
label 0
        localboot 0x80
label 1
        localboot 0x81
label 2
        localboot 0x82
label 3
        localboot 0x83
default 0
prompt   1
timeout  0

That's it!
Create an ISO from it with:

genisoimage -o /tmp/sys.iso \
    -b isolinux/isolinux.bin -c isolinux/boot.cat \
    -no-emul-boot -boot-load-size 4 \
    -boot-info-table \
    /tmp/x

And burn onto a CD. Voila, your USB boot enabler is ready!

Now I only need to find a small credit-card size CD-R blank somewhere ;)

And maybe Steffen Winterfeldt puts something like that as a hidden option into the default openSUSE ISOs. It would be quite useful IMHO.