Talk:GRUB

Merging the GRUB2 articles
There are 3 articles detailing GRUB2 now: The GRUB2 article is huge and overly verbose in some places, GRUB2 Quick Start is IMHO more something that this article should lead with and GRUB2 Config Variables should be probably weaved in under some #Config heading. Thoughts? /Ni1s 01:32, 20 March 2012 (UTC)
 * GRUB2
 * GRUB2 Config Variables
 * GRUB2 Quick Start


 * 1. I moved GRUB2 Config Variables to GRUB2/Config Variables for now, but it should be merged with GRUB2, as there is a lot of overlap already.
 * 2. I think it is useful to keep GRUB2 Quick Start and the more extensive GRUB2 separate, as is. Make sure proper referral is present in the introduction of both articles.
 * 3. Some parts of GRUB2 can be moved to subpages, e.g. GRUB2 to "GRUB2/Troubleshooting"
 * — yngwin (wiki admin) (talk) 07:44, 17 July 2012 (UTC)

Grub2 Breakage

 * 1) grub_platforms_emu is broken. It would appear if a user is on a 32bit pc, they would only need the grub_platforms_efi-32 and grub_platforms_pc USE flags set, not all of these!
 * 2) What is needed, and what isn't needed, should be specified. ie. Users wanting to just get up and running aren't going to be worried about fonts... although I'm being a little conclusional on this one.
 * 3) The grub-2 ebuild doesn't create /boot/grub, and users shouldn't have to being going into the system folders and using chmod (ie. chmod +x /etc/grub/*). This stuff should be completed by the ebuild script.

Again, forgive me for being a little ahead as I have yet to successfully get grub2 installed. Should happen shortly though.

Yes. Users (using the handbook install) are likely starting to likely starting to need grub-2 for GPT partitioning of 2+ TiB hard drives as MBR is limited to <=2TiB!

Grub2 Unfocused and Imprecise Install Target
If I'm correct, grub2 will only boot GPT (GUID) "Windows 7" partitions if grub2 is installed within the EFI|UEFI partition (ie. sda or hd0 within /efi).

The following is a typical "Windows 7" install to the hard drive using GPT (GUID) instead of MBR partition layout:

Number Start (sector)    End (sector)  Size       Code  Name 1           2048          206847   100.0 MiB   EF00  EFI system partition 2         206848          468991   128.0 MiB   0C01  Microsoft reserved part 3         468992      5846093823   2.7 TiB     0700  Basic data partition
 * 1) gdisk /dev/sdb

Or in English, /dev/sda1 is the 100MiB EFI/UEFI MS parition, /dev/sda2 Another MS reserved partition, /dev/sda3 is the actual Windows 7 install partition.

If a user tries to install grub2 to the usual /dev/sda device and tries doing:

insmod part_gpt insmod fat insmod search_fs_uuid insmod chain

set root=(hd1,gpt1) chainloader /efi/Microsoft/Boot/bootmgfw.efi

search --fs-uuid --no-floppy --set=root $YOUR_UUID # ie. blkid /dev/sdb1 chainloader ($root)/efi/Microsoft/Boot/bootmgfw.efi
 * Or, use the search method which helps when moving partitions around -- but UUID will change on resize?

Users will then be presented with a wonderful mysterious "invalid signature" error.

Trying "chainloader --force" will only cause a black screen with no activity or a reboot if the user tries to designate the ntfs "Windows 7" parition instead of "Windows 7" efi partition.

*** Hang on, I just realized I might have been trying to chainload /dev/sda2 and not /dev/sda3 directly! *** (I'll be back to after further troubleshooting.)

One definite vagueness of Grub2's documentation and Grub2's WIKI pages are it's specified install target. Users can either install Grub2 to /dev/sda or to /efi! From the current documentation, it wasn't immediately clear to me. From what I understand, users installing Grub2 to /efi which also requires manually adding a Grub2 boot line to the BIOS BOOT screen, avoid the Windows 7 "invalid signature" above. What joy.

As far as specifying partitions by UUID, I prefer to keep things simple incase I change or move partitions around. Not sure if the blkid UUID is preserved on parition resize.

In the end, prefer to keep things simple incase something breaks and not waste time making so many changes within config files when moving from different software versions. This way, if something breaks, I have more of a definite idea where something is broke. --Roger 13:30, 25 October 2012 (UTC)