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

Sun Jan 27 13:31:37 CET 2013

On 20/01/13 17:42, Maurice Batey wrote:
+> On Sun, 20 Jan 2013 14:50:06 +0000, Barry Jackson wrote:
+>
+>>   I repeat - "Installing the grub2 package"
+>
+>    OK - so you differentiate between "installing with GRUB2" and
+> "installing the GRUB2 packge?
+>
+I am differentiating between "# urpmi grub2" and the use of the 
+"grub2-install" command.
+>    Does the former include the latter?
+> Or do you mean one can install with GRUB Legacy and then go on to
+> install the GRUB2 *package* (which presumably doesn't do anything but
+> make itself available for the purposes you described)?
+>
+Exactly, except that it does create a menu and builds it's kernel 
+(core.img) which it places in the /boot/grub2 directory ready for use.
+It does no more than this and does not affect the existing MBR or PBR in 
+any way.
+
+>> This automatically creates core.img in /boot/grub2/i386-pc/ which
+>> allows
+>> you to boot into it from either grub2 using the multiboot command or from
+>> legacy, using the menu entry shown in the readme.
+>
+>     What/where is the 'multiboot command'?
+
+multiboot is a grub2 command to boot using core.img directly.
+Below is my entry for Mga3 in my "master" grub2 grub.cfg which is in a 
+small grub partition at the start of sda. My MBR points to this 
+partition, so all OS's are either chainloaded or multibooted from the 
+manually created entries in this grub.cfg
+
+menuentry 'Mageia-3' {
+search --no-floppy --label --set=root mageia-3
+multiboot /boot/grub2/i386-pc/core.img
+
+My limited understanding is that it is similar to chainloading but does 
+not need embedded code in the PBR. Since grub2 can read the filesystem 
+(with the appropriate modules loaded) it can navigate to the location of 
+core.img and launch it.
+A useful side effect is that grub legacy may be installed to the PBR and 
+used if required, using:-
+
+menuentry 'Mageia-3 {
+search --no-floppy --label --set=root mageia-3
+chainloader +1
+}
+
+>> Did you test it in Mageia as described in the README.Mageia ?
+>
+>      The GRUB2 I tried was from Ubuntu 12.01 and Mint 13, not Mageia.
+>
+>> If you add Mageia (grub2) entry to menu.lst as described and boot into
+>> the Grub2 menu it will have all your legacy systems listed. Do they
+>> not boot? .
+>
+>    Good question. The "GRUB2-to-Grub Legacy' boots I attempted via GRUB2
+> in the MBR all failed.
+>     Next time I get the netbook out I will try booting a GRUB Legacy
+> install via a GRUB Legacy boot menu entry for booting a GRUB2 install.
+> (Remember, it has GRUB Legacy in the MBR.)
+
+Yes that's fine
+>
+> But I expect the result to be the same as booting GRUB legacy from
+> GRUB2 in the MBR.
+>
+:\
+
+> If the failure to boot  was caused by a faulty GRUB2 component, as has
+> been suggested, then the test will have to await my installing Mageia-3
+> with GRUB2, which may not happen very soon.
+>
+
+Have fun ;)
+
+Barry
+