On Thu, Mar 05, 2020 at 06:40:01PM +0800, Michael Chang wrote: > 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.
Could you split this paragraph into a few sentences? Now it does not read very well... > 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 s/; on modern disks, it/. Additionally, 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 s/For SSD, it/E.g. 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 s/In case legacy/In case of legacy/ s/partition not/partition is not/ > +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. Daniel _______________________________________________ Grub-devel mailing list Grub-devel@gnu.org https://lists.gnu.org/mailman/listinfo/grub-devel
