grub-probe for nested BSD partition on Linux (was: [PATCH 1/1] add --partuuid to probe)

[Andrei Borzenkov]

28.02.2017 17:08, Vladimir 'phcoder' Serbinenko пишет:
>>
>> OK I see, kernel skips BSD partition marked as "unused".
>>
>> So it appears that kernel always puts special nested partitions after
>> normal logical MSDOS partitions, so it will not skew MSDOS partition
>> numbers.
>>
>> [    1.529752]  vda: vda1 vda2 vda3 < vda5 vda6 >
>>                 vda2: <openbsd: vda7 >
>>
>>
>>         /*
>>          * Look for partitions in two passes:
>>          * First find the primary and DOS-type extended partitions.
>>          * On the second pass look inside *BSD, Unixware and Solaris
>> partitions.
>>          */
>>
>> For such partition (vda7) PARTUUID is empty.
>>
>> P.S. I wonder whether we correctly map such partition ... no, we do not.
>>
>> 10:~ # cat /tmp/foo
>> (hd0) /dev/vda
>> 10:~ # grub2-probe -m /tmp/foo -t compatibility_hint -d /dev/vda2
>> hd0,msdos2
>> 10:~ # grub2-probe -m /tmp/foo -t compatibility_hint -d /dev/vda5
>> hd0,msdos5
>> 10:~ # grub2-probe -m /tmp/foo -t compatibility_hint -d /dev/vda7
>> hd0,msdos2
>>
> WAI. In case when subpartition starts at the same sector as partition
> itself.
> 

Sorry? vda7 is 256M, how can you suddenly pretend it is 2G?

10:~ # fdisk -l /dev/vda
Disk /dev/vda: 5 GiB, 5368709120 bytes, 10485760 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x882b18da

Device     Boot   Start      End Sectors  Size Id Type
/dev/vda1          2048  2099199 2097152    1G 83 Linux
/dev/vda2       2099200  6293503 4194304    2G a6 OpenBSD
/dev/vda3       6293504 10485759 4192256    2G  5 Extended
/dev/vda5       6295552  6819839  524288  256M 83 Linux
/dev/vda6       6821888  7346175  524288  256M 83 Linux
10:~ # fdisk -l /dev/vda2
Disk /dev/vda2: 2 GiB, 2147483648 bytes, 4194304 sectors
Geometry: 16 heads, 63 sectors/track, 10402 cylinders
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: bsd

Slice   Start      End  Sectors  Size Type     Fsize Bsize Cpg
a     2099200  2623488   524289  256M boot         0     0   0
b     2099200  2623488   524289  256M unused       0     0   0
c     2099200  6293503  4194304    2G unused       0     0   0
d           0 10485215 10485216    5G unused       0     0   0

Partition table entries are not in disk order.