Re: _primary_constraint(): start_geom is uninitialized if min_geom==0 && cylinder_size < dev->length. Debian bug #602568

[Jean-Christian de Rivaz]

Jim Meyering a écrit :
> Jean-Christian de Rivaz wrote:
> ...
> > Your patch work fine, thank you for providing it.
> >
> > address@hidden:/home/jcdr/parted-git/parted/build-O0# parted/parted
> > /dev/sdb print
> > Model: disk2go PURE II (scsi)
> > Disk /dev/sdb: 5243kB
> > Sector size (logical/physical): 512B/512B
> > Partition Table: msdos
> >
> > Number  Start  End     Size    Type     File system  Flags
> >  1      5120B  5243kB  5238kB  primary
> >
> > The debug capture in attachment prove that your logic is the right one
> > for this case.
> >
> > Now I just wonder if parted should display FAT16 in the file system
> > field. Because fdisk do it:
> >
> > address@hidden:/home/jcdr/parted-git/parted/build-O0# fdisk -l /dev/sdb
> >
> > Disk /dev/sdb: 5 MB, 5242880 bytes
> > 1 heads, 10 sectors/track, 1024 cylinders
> > Units = cylinders of 10 * 512 = 5120 bytes
> > Sector size (logical/physical): 512 bytes / 512 bytes
> > I/O size (minimum/optimal): 512 bytes / 512 bytes
> > Disk identifier: 0x00000000
> >
> >    Device Boot      Start         End      Blocks   Id  System
> > /dev/sdb1               2        1024        5115    6  FAT16
> >
> > And parted do it for the /dev/sdc (the regular storage device of this
> > USB key):
> >
> > address@hidden:/home/jcdr/parted-git/parted/build-O0# parted/parted
> > /dev/sdc print
> > Model: disk2go PURE II (scsi)
> > Disk /dev/sdc: 2142MB
> > Sector size (logical/physical): 512B/512B
> > Partition Table: loop
> >
> > Number  Start  End     Size    File system  Flags
> >  1      0.00B  2142MB  2142MB  fat16
>
> Perhaps it should, depending on what it means.
> Is it reporting just the magic number, or is it reporting
> the existence of a file system of that type?
>
> It seems that 4MiB is the minimum size of a FAT16 file system,
> and at 2.5MiB, yours is well under the minimum, so with the latter
> interpretation, parted is correct not to report it as one.

Sorry, I failed to find where this /deb/sdb1 partition is 2.5MiB in 
size. Seem to be 5.1MiB (5238kB, or (1024-2+1)*512*10/2.0**20=4.99MiB 
according to fdisk) to me ( > 4MiB ). This is also confirmed by the 
system while mounting the /deb/sdb1 partition:

address@hidden:/home/jcdr/parted-git/parted/build-O0# mount /dev/sdb1 /mnt
address@hidden:/home/jcdr/parted-git/parted/build-O0# df -h /dev/sdb1
Filesystem            Size  Used Avail Use% Mounted on
/dev/sdb1             5.0M     0  5.0M   0% /mnt

I also tryed with a FAT12 partition type witch is know to work for 
floppy disk as small as 720kiB and got the same result:

address@hidden:/home/jcdr/parted-git/parted/build-O0# fdisk -l /dev/sdb

Disk /dev/sdb: 5 MB, 5242880 bytes
1 heads, 10 sectors/track, 1024 cylinders
Units = cylinders of 10 * 512 = 5120 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               2        1024        5115    1  FAT12
address@hidden:/home/jcdr/parted-git/parted/build-O0# parted/parted /dev/sdb 
print
Model: disk2go PURE II (scsi)
Disk /dev/sdb: 5243kB
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number  Start  End     Size    Type     File system  Flags
 1      5120B  5243kB  5238kB  primary

Now you could argument that FAT12 is not supported by parted, but the 
FAT16 result on a 5MiB partition is still a strange result to me.

Jean-Christian de Rivaz