Wed Apr 24 11:49:43 EDT 2013
Fixing Ubuntu triple boot after upgrade
Computer has a convoluted boot setup:
- sda1 VFAT compaq rescue partition with DOS grub installed
- sda2 NTFS XP
- sda5 Ubuntu
- sda6 Debian
Reason? PC has trouble Ubuntu / Debian GRUB directly from USB
The point is to boot from the VFAT and chainload into the debian
bootloader, which can boot Ubuntu. However, Ubuntu will override the
MBR, so to fix, boot from GRUB 0.97 on USB disk into Debian (or
Ubuntu) and fix the MBR.
- make a bootable grub 0.97 USB disk
cp stage1 stage2 to /boot/grub/
use a device map file "(hd0) /dev/sdk" with grub --device-map=<file>
at grub> do
- boot the USB disk (BIOS: ESC = boot menu)
- then start Debian manually at grub>
or use "root (hd1,6)" to boot Ubuntu.
- VFAT grub boot from MBR
mount the VFAT and copy /boot/grub.elf to /tmp, chmod it and execute
it. then do the same thing as for preparing the USB drive.
with device-map "(hd0) /dev/sda", at grub> do