The firmware and the OS may disagree on the disk configuration and size.
Although such a setup should be avoided users are unlikely to know about
the problem, assuming everything behaves like the OS. Tolerate this as
best we can and trust the reported on-disk location over the firmware
when looking for the backup GPT. If the location is inaccessible report
the error as best we can and move on.
Portions of the code attempted to handle the fact that GPT entries on
disk may be larger than the currently defined struct while others
assumed the data could be indexed by the struct size directly. This
never came up because no utility uses a size larger than 128 bytes but
for the sake of safety we need to do this by the spec.
Basic usage would look something like this:
gptprio.next -d usr_dev -u usr_uuid
linuxefi ($usr_dev)/boot/vmlinuz mount.usr=PARTUUID=$usr_uuid
After booting the system should set the 'successful' bit on the
partition that was used.
In order to do anything with partition GUIDs they need to be stored in a
proper structure like the partition type GUIDs. Additionally add an
initializer macro to simplify defining both GUID types.
The first hint of something practical, a command that can restore any of
the GPT structures from the alternate location. New test case must run
under QEMU because the loopback device used by the other unit tests does
not support writing.
The header location fields refer to 'this header' and 'alternate header'
respectively, not 'primary header' and 'backup header'. The previous
field names are backwards for the backup header.
This module is a new implementation for reading GUID Partition Tables
which is much stricter than the existing part_gpt module and exports GPT
data directly instead of the generic grub_partition structure. It will
be the basis for modules that need to read/write/update GPT data.
The current code does nothing more than read and verify the table.
1. Make sure files are not multiple of block size. This will ensure tail packing
for squash4 and may also trigger more codes paths in other filesystems.
2. Call mksquashfs with -always-use-fragments to force tail packing.
proot creates hidden files with .proot prefix and name
derived from real file name. So decrease file name length
and path depth. For some reason depth 85 also results in
undeleteable directory, so use 84 instead of 85.
LVM miscalculates bitmap size with small extent, so start with 16K as
for other RAID types.
Until version 2.02.103 LVM counts metadata segments twice when checking
available space, reduce segment count by one to account for this bug.
Write activity with LVM/RAID can happen after filesystem is unmounted.
In my testing modification time of loop files was 15 - 20 seconds
after unmount. So use time as close to unmount as possible as
reference instead.
Michael Marineau
Alex Crawford
Andrei Borzenkov
Vladimir Serbinenko