[Mageia-dev] Grub2 vs. Grub Legacy in M3

Mon Jan 21 01:01:30 CET 2013

On 01/20/2013 02:58 PM, Maurice Batey wrote:
+> On Sun, 20 Jan 2013 20:04:32 +0200, Thomas Backlund wrote:
+>
+>> http://svnweb.mageia.org/packages/cauldron/grub2/current/SOURCES/README.Mageia?view=markup
+>    Many thanks, Thomas!
+>
+Look, I don't don't want to restate the obvious, but you *do* realize 
+that in order for chainloader to work, you actually have to install the 
+secondary bootloader on the PBR of its owing partition ?  You can't just 
+have installed grub on your MBR at some point in the past, then install 
+grub2 (or anything else, for that matter) on the MBR again, and expect 
+your original partitions to boot ?
+
+In MGA install terms, and specific to the case of grub2 on the MBR 
+trying to boot grub on a PBR, you have to boot the grub partition (or do 
+the boot-elsewhere/chroot thing), modify the /boot/grub/install.sh to 
+not target the MBR (stage2=(hd0)) but indicate the PBR (stage2=(hd0,x)) 
+and rerun install.sh to install grub on the PBR.
+
+In terms of the install paradigm, you have to choose to install the 
+bootloader to the PBR (sdaX) rather than the MBR (sda).  Otherwise, when 
+the MBR bootloader, whether grub2 or grub, boots and chains to the PBR 
+of the desired partition, there won't be anything there in the PBR to boot.
+
+If you need clarification on this, ask, and give specifics.  The 
+objective of chainloading is to have each PBR (partition) behave as if 
+it is its own MBR.  If you try to point grub2 menu entries to native 
+partiton grub files, or vice versa, you are just asking for trouble.  
+The clean way to do it is to use chainloading to link the MBR (whatever 
+it is) to the PBR (whatever it is), and let the PBR do the bootloading 
+for its own partition according to its own needs.
+
+If you do it this way, you can install whatever you want as a bootloader 
+on the MBR, and each partition can have whatever BIOS-compliant 
+bootloader it wants, including grub, grub2, lilo, OS/2, DOS, or Wndows.
+