Further to the discussion about disabling btrfs zstd support for i386-pc[1], this paragraph in manual about mbr gap size doesn't seem to hold true any longer.
"You must ensure that the first partition starts at least 31 KiB (63 sectors) from the start of the disk" As in many occasions we inevitablely have to provide core image size that goes beyond 31 KiB, this statement becomes a true liability as people would be misguided and think it is still fine to use small MBR gap, that has always been a headache in distribution's upgrade path as growing new feature would render the size requirement bigger but no way for the user to relocate their partitions. The patch tries to correct the paragraph with a more practical size that works for grub and also for modern computer systems in general. [1] https://lists.gnu.org/archive/html/grub-devel/2019-11/msg00025.html Signed-off-by: Michael Chang <mch...@suse.com> --- docs/grub.texi | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) diff --git a/docs/grub.texi b/docs/grub.texi index 83979af38..651468268 100644 --- a/docs/grub.texi +++ b/docs/grub.texi @@ -845,12 +845,20 @@ only be used if the @file{/boot} filesystem is on the same disk that the BIOS boots from, so that GRUB does not have to rely on guessing BIOS drive numbers. -The GRUB development team generally recommends embedding GRUB before the -first partition, unless you have special requirements. You must ensure that -the first partition starts at least 31 KiB (63 sectors) from the start of -the disk; on modern disks, it is often a performance advantage to align -partitions on larger boundaries anyway, so the first partition might start 1 -MiB from the start of the disk. +The GRUB development team generally recommends embedding GRUB before the first +partition, unless you have special requirements. You must ensure that the first +partition starts at least 1 MiB from the start of the disk; on modern disks, it +is often a performance advantage to align partitions on larger boundaries and 1 +MiB is the least common multiple of many used alignment sizes. For SSD, it +became crucial to have the partition correctly aligned to avoid excessive +read-modify-write cycles and thus modern tools set to use 1 MiB as a stardard +practice. + +In case legacy systems that cannot boot if first partition not on the cylinder +boundary, the fallback blocklist install method should remain working for them +if the core image growing too much someday. Here we just can't advertise that +31 KiB (63 sectors) is a sensible size any longer as that would pose great +constraint to include new features as time goes by. @heading GPT -- 2.16.4 _______________________________________________ Grub-devel mailing list Grub-devel@gnu.org https://lists.gnu.org/mailman/listinfo/grub-devel
