On Tue, 26 Mar 2013 12:38:51 +0000, David WE Roberts wrote: > On Tue, 26 Mar 2013 11:46:41 +0000, David WE Roberts wrote: > >> On Sun, 24 Mar 2013 23:47:24 +0400, Andrey Borzenkov wrote: >> >>> В Sun, 24 Mar 2013 16:58:55 +0000 (UTC) >>> David WE Roberts <[email protected]> пишет: >>> >>>> On Sun, 24 Mar 2013 16:14:48 +0000, David WE Roberts wrote: >>>> >>>> > Should grub rescue started from an MBR disc be able to see GPT >>>> > partitions? >> >> <snip> >> >>> If you still can boot in original configuration, reinstall grub while >>> explicitly adding part_gpt: >>> >>> grub-install --modules=part_gpt ... >>> >>> If you cannot return to original configuration - just follow boot >>> recovery procedure for your distro. >> >> Done that. >> >> When I disconnect the original MBR data drive and connect the new GPT >> data drive and boot grub of the MBR disc and go into grub rescue >> >> I still find that 'ls' can only see one drive, the one with the MSDOS >> partitions on. >> >> If I 'insmod part_gpt' it does not complain, but still can't see the >> GPT drive. >> >> Not enough in core.img to chain load Windows either. > > Test #2 > > Boot from Ubuntu 12.04 Live CD into 'Try' > > startup Terminal > > sudo bash > > mount /dev/sdb2/ /mnt/ > > [ls to confirm correct filestore mounted] > > grub-install --boot-directory=/mnt/boot /dev/sda > > reboot, and get > > error: no such device: 28ba1903-0731-40e2*8ce2-55e5597293c2 > > >set > > prefix=(hd0,2)/boot/grub > > root=hd0,2 > >>ls > > (hd0) > > > So as far as I can see grub-install has installed grub on /dev/sda and > set up core.img to cope with a GPT disc and correctly identified the > disc and that /boot/grub and /root are on partition 2 of the disc. > > When the initial bit of grub starts to load, it is unable to see the GPT > disc (no such device:) and reverts to the only disc it can see, the MBR > disc. > > However it hasn't got the module 'part_msdos' included so it can't even > see the partitions on the MBR disc. > > [I checked this - at the grub rescue> prompt insmode part_gpt worked, > insmod part_msdos failed.] > > So I think this is a bug not a feature. > > It looks as though currently the only way that I can get my GPT disc up > and running using grub2 from an MBR disc is to have /boot/grub in a > separate mini-partition on the MBR disc. Assuming even that works. > > I will try a full install of Ubuntu 12.04 onto the GPT disc, nominating > the MBR disc as the location for grub, and see what happens. > However I fully expect the same failure. > > Bug: grub 2 on initial boot does not correctly support GPT discs with > the module 'part_gpt'. > It fails to recognise the disc or the partitions. > > Note that the discs are configured in AHCI mode.
Test #3 Installed Ubuntu 12.04 64 bit to the partition on the GPT drive where it was previously installed. Nominated MBR drive as boot drive. Same failure as Test #2. Now, of course, I can't boot anything because when I revert back to a full MBR configuration core.img is set up for GPT partitions so can't see the MBR partitions, although it can see both MBR discs. About to rerun Test #2 on the MBR configuration to reset core.img (I hope). Cheers Dave R _______________________________________________ Help-grub mailing list [email protected] https://lists.gnu.org/mailman/listinfo/help-grub
