On Tue, Apr 10, 2012 at 6:00 AM, Stroller <strol...@stellar.eclipse.co.uk> wrote: > > On 9 April 2012, at 13:04, Canek Peláez Valdés wrote: >>>> … >>>> This means ext4 mandatory if you want to use it, and this (usually) >>>> means GRUB2, which is still considered beta. >>> >> … >> Interesting. Do you have extents enabled in the filesystem? Mine does: >> >> # tune2fs -l /dev/sda4 | grep features >> Filesystem features: has_journal ext_attr resize_inode dir_index >> filetype needs_recovery extent sparse_super large_file uninit_bg > > # df -Th > Filesystem Type Size Used Avail Use% Mounted on > rootfs rootfs 228G 5.8G 211G 3% / > /dev/root ext4 228G 5.8G 211G 3% / > devtmpfs devtmpfs 875M 212K 875M 1% /dev > rc-svcdir tmpfs 1.0M 60K 964K 6% /lib64/rc/init.d > cgroup_root tmpfs 10M 0 10M 0% /sys/fs/cgroup > shm tmpfs 876M 0 876M 0% /dev/shm > # tune2fs -l /dev/root | grep extent > Filesystem features: has_journal ext_attr resize_inode dir_index > filetype needs_recovery extent flex_bg sparse_super large_file huge_file > uninit_bg dir_nlink > >> I was under the impression that GRUB legacy could not read ext4 >> filesystems with extents enabled; that was the primary reason I >> migrated to GRUB2. I believe there is a patch for GRUB legacy which >> adds ext4+extents support, but I don't think Gentoo applies it. > > No idea where it comes from, but you can see for yourself now you know to > look.
OK, I went out and did my homework. GRUB legacy upstream doesn't support ext4 partitions (using extents, of course; without extents, they can be mounted as ext3), but Gentoo (as almost any other distribution under the sun) applies a patch to support it. Actually, it applies 37 patches, contained in grub-0.97-patches-1.12.tar.bz2, one of them called 850_all_grub-0.97_ext4.patch, which says: Gentoo bug #250829 - Include support for booting from ext4 partitions. This is the respun and tested patch adapted from http://code.google.com/p/grub4ext4/ so that it will apply with the rest of the Gentoo patches. Tested with: /boot on ext2 /boot on ext3 /boot on ext4 / on ext4 (no seperate /boot) Patch ported by Diego E. Pettenò (flameeyes) Testing by Robin H. Johnson (robbat2) Signed-off-by: Diego E. 'Flameeyes' Pettenò <flamee...@gentoo.org> Signed-off-by: Robin H. Johnson <robb...@gentoo.org> So mistery solved: GRUB legacy in Gentoo supports ext4, but it differs from upstream. When I was doing research for converting my filesystem to ext4, everywhere I looked it said that GRUB legacy doesn't support ext4... because it doesn't. Gentoo patches the sources, but upstream GRUB legacy does not support ext4. So I can finally stop telling people to migrate to GRUB2 if they want to use ext4. Thanks Stroller. Regards. -- Canek Peláez Valdés Posgrado en Ciencia e Ingeniería de la Computación Universidad Nacional Autónoma de México
