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

Sun Jan 20 14:06:19 CET 2013

On 01/20/2013 07:55 AM, Maurice Batey wrote:
+> So I suspect that he (like me) does not know how to boot a GRUB Legacy 
+> install from a GRUB2 boot menu. (Yes, I know GRUB2 boot menus do show 
+> options to boot existing GRUB Legacy installs, but in my experience 
+> (with Ubuntu and Mint) they *fail* to boot them.) Despite my requests 
+> in various newsgroups, NO ONE has offered a description of how to get 
+> a GRUB2 boot menu to successfully boot a GRUB Legacy install. Can you, 
+> please, Frank? 
+
+I've never used grub2 myself.  But the article states that if you have 
+grub2 on the MBR and define a chainloader menu.lst entry for a partition 
+that has grub on the PBR, it works.
+
+That makes sense.  Chainloading simply means that the MBR bootloader 
+reads the PBR into memory and passes control to it exactly as the BIOS 
+reads the MBR into memory and passes control to it.  Assuming that both 
+grub and grub2 support chainloading correctly, neither one of them 
+should have any idea whether it's an MBR that was loaded by the BIOS or 
+a PBR that was chainloaded by an MBR.
+
+This glosses over other sources of problems like UEFI and GPT, but it 
+has always been the case that if you want to support multiple boot 
+loaders, you have to use a lowest common denomination architecture that 
+they all support.
+