On Wednesday, February 02, 2011 20:20:02 Allen Weiner wrote: > On Wed, 2011-02-02 at 16:52 -0500, Chris Knadle wrote: > > There are several situations where you'd want to install GRUB2 into a > > /boot partition -- however, unfortunately installing GRUB2 onto a > > partition rather than the MBR isn't officially supported AFAIK. Doing > > so requires using "blocklists" (that means a list of disk blocks), which > > is the complaint you'll get from GRUB2. I'm using this configuration on > > one Desktop box, and over time I've found it to be a bit buggy and > > problematic, because upon upgrades sometimes GRUB2 installs itself into > > the MBR instead of /boot, which causing the bootup to endlessly restart. > > > > So if you have the choice, install GRUB2 into the MBR. > > Thanks for the explanation of blocklists Chris. I just recently had a > similar dilemma. On a newly built PC, I set up dual boot of Fedora 14 > and Ubuntu 10.10. Fedora 14 was installed first and Anaconda (installer) > installed Grub Legacy in the MBR. I then installed Ubuntu 10.10. I > didn't notice Ubuntu installer giving me a choice of where to install > Grub2. It overwrote the MBR. But it noticed Fedora and included it in > the boot menu. However, Fedora kernel upgrades would not be incorporated > in that boot menu.
Yes, that's right. Running two different distros is one of the specific situations in which you'd want to chainload, using one boot loader in the MBR, and another boot loader in a /boot partition for both Ubuntu and Fedora -- because without doing that, kernel upgrades won't show up in their respective boot menus without manual intervention. The reason is that Grub2 with Ubuntu is what is handling bootup, and this Grub2 menu does not get modified from within Fedora when a new kernel is installed So for instance the way I'd set that up chainloading would be this way: MBR --> GAG boot loader [ http://gag.sourceforge.net/ ] \--> Ubuntu 10.10 \--> Grub in /boot (partition /dev/sda1) \--> Fedora 14 \--> Grub in /boot (partition /dev/sda2) Before anyone asks why I'd use the GAG boot loader, it's to eliminate confusion -- because if you use Grub2 in the MBR, then Grub2 comes up twice -- once for the MBR to chainload, and once for each distro. By using the GAG boot loader it's clear which step in the bootup is happening. Colorizing the boot menu differently with Grub in the MBR could also work to eliminate the confusion, but I wanted to make it "really obvious" by using a completely different boot loader altogether -- and that's been working for me. This is also why if Grub2 gets confused and installs itself into the MBR, booting on my Desktop breaks. [It would also break if I used Grub2 for the MBR bootup, just break differently.] > So I had the dilemma of whether to use Grub or Grub2 in the MBR. > > I decided based on this very informative Grub2 tutorial: > http://www.dedoimedo.com/computers/grub-2.html > > He covers dual boot where one OS uses Grub and the other uses Grub2. > > His recommendation is that for dual boot, due to its long track record, > Grub should be the choice for the MBR. Grub2 should go in the boot > sector of the partition for the second OS. He feels Grub is more > dependable than Grub2. Unfortunately I think he's right, but also unfortunately Grub Legacy is no longer supported, and there are a bunch of filesystems it cannot handle without using a /boot partition (XFS, JFS, EXT4, etc). And the other dilemma is that Grub2 doesn't officially support being installed in a partition rather than the MBR. > He acknowledges that installation of Grub2 in the boot sector is > discouraged by the Grub2 developers. Yep. > Grub2 is supposed to be a significant improvement over Grub. Yet Grub > fully supports installation in the partition boot sector and Grub2 > doesn't. Isn't this a significant step backward? Grub2 has several benefits and several drawbacks compared with Grub Legacy. Honestly I can't call it better or worse -- mostly what I can say is it's more complicated. -- Chris -- Chris Knadle [email protected] _______________________________________________ Mid-Hudson Valley Linux Users Group http://mhvlug.org http://mhvlug.org/cgi-bin/mailman/listinfo/mhvlug Upcoming Meetings (6pm - 8pm) MHVLS Auditorium Feb 2 - Zimbra Mar 2 - MHVLUG 8th Anniversary - Show and Tell Apr 6 - Introduction to IPv6
