On Wed, 27 Mar 2013 13:25:05 -0600, Chris Murphy wrote: > On Mar 27, 2013, at 3:21 AM, David WE Roberts > <[email protected]> wrote: > >> As posted elsewhere, with all 3 discs connected and grub-install run >> against a GPT partition, on reboot I can see the two MBR discs and not >> the GPT disc. > > This is all very unclear terminology, as I mentioned elsewhere. > > This GPT disk contains a BIOS Boot partition? And you used grub-install > on that GPT disk? And when you reboot you're absolutely certain it's > loading GRUB off the GPT disk? > > It doesn't make sense that GRUB loads from a GPT disk, and then can't > see that GPT disk. That's pretty inexplicable, don't you think? > > >> Because core.img has been built with part_gpt I can't see the >> partitions on either MBR disc. > > It sounds like os-prober isn't finding systems on those MBR partitioned > disks, therefore it's not building MBR support into the core.img. This > might have to do with an old version of os-prober, or maybe the > partitions os-prober is searching are encrypted. > > >> I note that the version (1.99) of grub2 is quite old - this is the >> version that ships with the latest version (12.04) of Ubuntu. > > 12.10 has 2.00-7 listed in the repos. I suspect you can still use it on > 12.04. I don't know if os-prober is a separate package, but I'd make > sure that too is as up to date as you can make it.
We seem doomed to exchange messages but completely fail to communicate. Throughout all of this grub *always* boots from the MBR on /dev/sda. The problem is that under certain circumstances it can't find /boot/grub. As Jordan has said, if when you run 'grub-install' the location of /boot/ grub is on a GPT disc then "part_gpt" will be included in core.img. If the location of /boot/grub is on an MBR disc then 'part_msdos' will be included in core.img. The initial job of 'core.img' is to get itself up and running and then locate the partition where /boot/grub resides and it can then proceed to load all the additional modules and set all the variables it needs to get ready to boot a variety of OS, and then present the user with a menu. The copy of 'core.img' stored in the MBR is a pared down version because of the lack of available space and the restricted environment it starts in. Once it has found /boot/grub it can then flesh itself out with all the other modules it needs such as for example NTFS support. Hopefully this makes things a little clearer :-) Cheers David _______________________________________________ Help-grub mailing list [email protected] https://lists.gnu.org/mailman/listinfo/help-grub
