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. Regards Dave R _______________________________________________ Help-grub mailing list [email protected] https://lists.gnu.org/mailman/listinfo/help-grub
