Commit f2d34fd9 authored by Will Drewry's avatar Will Drewry Committed by Linus Torvalds

Documentation: add pointer to name_to_dev_t for root= values

Update kernel-parameters.txt to point users to the authoritative comment
for name_to_dev_t.  In addition, updates other places where some
name_to_dev_t behavior was discussed.  All other references to root=
appear to be for explicit sample usage or just side comments when
discussing other kernel parameters.
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 avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2af14162
......@@ -106,13 +106,20 @@ separated by spaces:
To use the first on-chip serial port at baud rate 115200, no parity, 8
bits, and no flow control.
(*) root=/dev/<xxxx>
(*) root=<xxxx>
This specifies the device upon which the root filesystem resides. For
example:
This specifies the device upon which the root filesystem resides. It
may be specified by major and minor number, device path, or even
partition uuid, if supported. For example:
/dev/nfs NFS root filesystem
/dev/mtdblock3 Fourth RedBoot partition on the System Flash
PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF/PARTNROFF=1
first partition after the partition with the given UUID
253:0 Device with major 253 and minor 0
Authoritative information can be found in
"Documentation/kernel-parameters.txt".
(*) rw
......
......@@ -2245,6 +2245,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
ro [KNL] Mount root device read-only on boot
root= [KNL] Root filesystem
See name_to_dev_t comment in init/do_mounts.c.
rootdelay= [KNL] Delay (in seconds) to pause before attempting to
mount the root filesystem
......
......@@ -129,6 +129,20 @@ decimal 11 is the major of SCSI CD-ROMs, and the minor 0 stands for
the first of these. You can find out all valid major numbers by
looking into include/linux/major.h.
In addition to major and minor numbers, if the device containing your
root partition uses a partition table format with unique partition
identifiers, then you may use them. For instance,
"root=PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF". It is also
possible to reference another partition on the same device using a
known partition UUID as the starting point. For example,
if partition 5 of the device has the UUID of
00112233-4455-6677-8899-AABBCCDDEEFF then partition 3 may be found as
follows:
PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF/PARTNROFF=-2
Authoritative information can be found in
"Documentation/kernel-parameters.txt".
2.2) ro, rw
-----------
......
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