• Will Drewry's avatar
    init: add root=PARTUUID=UUID/PARTNROFF=%d support · 79975f13
    Will Drewry authored
    Expand root=PARTUUID=UUID syntax to support selecting a root partition by
    integer offset from a known, unique partition.  This approach provides
    similar properties to specifying a device and partition number, but using
    the UUID as the unique path prior to evaluating the offset.
    
    For example,
      root=PARTUUID=99DE9194-FC15-4223-9192-FC243948F88B/PARTNROFF=1
    selects the partition with UUID 99DE.. then select the next
    partition.
    
    This change is motivated by a particular usecase in Chromium OS where the
    bootloader can easily determine what partition it is on (by UUID) but
    doesn't perform general partition table walking.
    
    That said, support for this model provides a direct mechanism for the user
    to modify the root partition to boot without specifically needing to
    extract each UUID or update the bootloader explicitly when the root
    partition UUID is changed (if it is recreated to be larger, for instance).
     Pinning to a /boot-style partition UUID allows the arbitrary root
    partition reconfiguration/modifications with slightly less ambiguity than
    just [dev][partition] and less stringency than the specific root partition
    UUID.
    
    [sfr@canb.auug.org.au: fix init sections warning]
    Signed-off-by: default avatarWill Drewry <wad@chromium.org>
    Cc: Kay Sievers <kay.sievers@vrfy.org>
    Cc: Randy Dunlap <rdunlap@xenotime.net>
    Cc: Namhyung Kim <namhyung@gmail.com>
    Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
    Cc: Jens Axboe <axboe@kernel.dk>
    Signed-off-by: default avatarStephen Rothwell <sfr@canb.auug.org.au>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    79975f13
do_mounts.c 12 KB