On Mon, Feb 27, 2017, 20:11 Andrei Borzenkov <arvidj...@gmail.com> wrote:
> 27.02.2017 21:20, Vladimir 'phcoder' Serbinenko пишет: > > On Mon, Feb 27, 2017, 09:55 Andrei Borzenkov <arvidj...@gmail.com> > wrote: > > > >> 27.02.2017 03:37, Vladimir 'phcoder' Serbinenko пишет: > >> ... > >>>>>>> This is not NT-style. NT uses partition offset. Who uses this > format? > >>>> Are > >>>>>> > >>>>>> This is used by util-linux and Linux kernel. > >>>>>> > >>>>>> > >>>>>> * 6) PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF > representing > >>>> the > >>>>>> * unique id of a partition if the partition table provides > >> it. > >>>>>> * The UUID may be either an EFI/GPT UUID, or refer to an > >> MSDOS > >>>>>> * partition using the format SSSSSSSS-PP, where SSSSSSSS > is a > >>>>>> zero- > >>>>>> * filled hex representation of the 32-bit "NT disk > >> signature", > >>>>>> and PP > >>>>>> * is a zero-filled hex representation of the 1-based > >> partition > >>>>>> number. > >>>>>> > >>>>>>> you sure that partition numbers are synced with user? Even in > >> presence > >>>> of > >>>>>>> Solaris and bsd partitions. > >>>>>>> > >>>>>> > >>>>>> It is not clear what we should return for nested partition. I'm not > >> sure > >>>>>> whether linux kernel scans nested partitions at all in which case we > >>>>>> probably should follow the suite and assign PARTUUID to top-level > >>>>>> partitions only. > >>>>>> > >>>>> Linux scans nested partitions and it uses though numeration in > >> dev/sdaX, > >>>> in > >>>>> some cases shifting numbering of normal partitions. In those cases > grub > >>>> and > >>>>> Linux numeration get out of sync > >>>>> > >>>> > >>>> Can you provide example? > >>> > >>> Bsd and Solaris partitions. I remember we had problem with numbering of > >>> those. > >>> > >> > >> Linux ignores nested BSD partitions (just tested). There are no special > >> files created. Of course someone needs to test what happens under > >> *BSD/Solaris in this case. > >> > > Kpartx or normal sdX? Is bsd-partition support enabled in kernel build? > > > > 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. > > > >> > >> I never liked idea of artificial partition GUIDs for MBR, but as long as > >> only Linux is using them and we are consistent with its usage - so be > it. > >> > >>>> I tried to create nested partition table, but > >>>> Linux will not display it (actually attempt to "blockdev --rereadpt > >>>> /dev/vda5" fails with "Invalid argument"). > >>>> > >>>> if (!disk_part_scan_enabled(disk) || bdev != > bdev->bd_contains) > >>>> return -EINVAL; > >>>> > >>>> Where bdev->bd_contains points to containing device for partition and > to > >>>> itself for the whole disk. > >>>> > >>>> As util-linux does not scan partition table itself, it does show these > >>>> nested partitions either. > > > _______________________________________________ > Grub-devel mailing list > Grub-devel@gnu.org > https://lists.gnu.org/mailman/listinfo/grub-devel >
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