Re: PTUUID and PARTUUID (was: [PATCH v3] libblkid: print PTUUID, the partition table uuid)

[Gabriel de Perthuis <g2p.code@gmail.com>]

Le jeu. 13 juin 2013 15:30:35 CEST, Karel Zak a écrit :
> On Fri, Jun 07, 2013 at 07:27:00PM +0200, Gabriel de Perthuis wrote:
>> ---
>> v3: Call it ID_PART_TABLE_UUID in udev rules
>
> I have applied a little bit different version. Anyway, you have to
> modify udevd to make it usable with in built-in blkid. It also
> exports MBR ID (so the change is not GPT specific) as partition
> table pseudo UUID. Examples:
>
>  # blkid -p -o udev /dev/sda
>  ID_PART_TABLE_UUID=3549290f-417c-4941-8503-f7835109b821
>  ID_PART_TABLE_TYPE=gpt
>
>  # blkid -p -o udev /dev/sdb
>  ID_PART_TABLE_UUID=54e743a7
>  ID_PART_TABLE_TYPE=dos
>
>
> Note that I have also add support for Dos partitions pseudo-uuids. The
> implementation is compatible with Linux kernel root=PARTUUID= command
> line option.

v1 of the patch had those MBR ids, I deliberately removed them in v2
because they weren't unique on the disks I had.
Calling those UUIDs will create false expectations.

> The PARTUUID for Dos partitions is based on MBR Id and partition number,
> for example:
>
>   # blkid /dev/sdb1
>   /dev/sdb1: TYPE="ext2" PARTUUID="54e743a7-01" 
>
> is the first partition on disk with PTUUID=54e743a7. So you can use
>
>   # mount PARTUUID="54e743a7-01" /mnt/test
>
>     Karel