[parted-devel] ms-dos & pc98 disk label

[Jim Meyering]

kamesh waran <sjkameshwaran at yahoo.co.in> wrote:
>     I have a scsi disk drive which has been partition by sfdisk. When I used Parted-1.8.2
> to print the partitions, It gave me the below error.
>
> "No Implementation: Partition 1 isn't aligned to cylinder boundaries"
>
> I have gone through the code and it seems like it sequentially checks for amiga, bsd....etc and ms-dos
> disk labels. When probing for ms-dos, it matches the DOS PARTITION-MAGIC. But it also matches the pc98 when it
> come across the below code in ms_dos_probe. pc98_probe in turn calls the read_table and there i got the above error.
>
> #ifdef ENABLE_PC98
>         /* HACK: it's impossible to tell PC98 and msdos disk labels apart.
>          * Someone made the signatures the same (very clever).  Since
>          * PC98 has some idiosyncracies with it's boot-loader, it's detection
>          * is more reliable */
>          disk_type = ped_disk_type_get ("pc98");
>         if (disk_type && disk_type->ops->probe (dev))
>                 return 0;
> #endif /* ENABLE_PC98 */
>
> When i commented out the above calls to pc98 probe in ms_dos_probe, it shows me the correct listing of the disk.
> Is ms_dos and pc98 disk label are same ?
>
> Can you please through some light on this.

Thanks for the report.
I'm no expert on this, but do see you can configure parted to do what you want:

    ./configure --disable-pc98

Currently the default is to enable that check,

    $ ./configure --help|grep pc98
      --enable-pc98          build with pc98 support default=yes

and you can see that you would not be the first to want to
turn it off:

    $ grep -A1 PC9 configure.ac
      AC_DEFINE(ENABLE_PC98, 1,
                [Include PC98 partition tables.  (Sometimes excluded to avoid
                 collisions with msdos partition tables])

Your experience suggests it'd be good to change the default,
but doing that might cause more problems than it'd solve.