[gentoo-user] Trying to loopback mount partition from a disk image

[Stroller]

Hi there,

With reference to a couple of previous threads:
   http://thread.gmane.org/gmane.linux.gentoo.user/193263
   http://thread.gmane.org/gmane.linux.gentoo.user/197120

Here's what I'm trying:

$ ls -lh sda.dd.img
-rw-r--r-- 1 stroller users 77G 2009-11-22 03:51 sda.dd.img
$ file sda.dd.img
sda.dd.img: x86 boot sector, Microsoft Windows XP MBR, Serial  
0x1890189; partition 1: ID=0x7, active, starthead 1, startsector 63,  
160810587 sectors, code offset 0xc0
$ parted sda.dd.img p
WARNING: You are not superuser.  Watch out for permissions.
Model:  (file)
Disk /path/to/sda.dd.img: 82.3GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number  Start   End     Size    Type     File system  Flags
  1      32.3kB  82.3GB  82.3GB  primary  ntfs         boot

$ fdisk -l sda.dd.img
You must set cylinders.
You can do this from the extra functions menu.

Disk sda.dd.img: 0 MB, 0 bytes
255 heads, 63 sectors/track, 0 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x01890189

      Device Boot      Start         End      Blocks   Id  System
sda.dd.img1   *           1       10010    80405293+   7  HPFS/NTFS
Partition 1 has different physical/logical endings:
      phys=(1023, 254, 63) logical=(10009, 254, 63)
$
$ sudo losetup -o 8225280 /dev/loop0 sda.dd.img
$ sudo mount -v /dev/loop0 /mnt/floppy/
mount: you didn't specify a filesystem type for /dev/loop0
        I will try all types mentioned in /etc/filesystems or /proc/ 
filesystems
Trying #
Trying #vfat
Trying fuseblk
mount: you must specify the filesystem type
$


If I format a USB stick as NTFS I can mount and read it fine, so NTFS  
driver modules are correctly compiled into the kernel.

I can `losetup` to a loop device and then `fdisk -l` or `parted /dev/ 
loop0 p` and see the partitions.

I've tried with an offset of 512 bytes instead of 8225280 with the  
same results - I guess I'm getting a little confused about what the  
correct offset should be. Thinking about this now it seems "obvious"  
that 512 should be correct, but anyway, that isn't working.

I get the same as Pat trying this: http://article.gmane.org/gmane.linux.gentoo.user/197123

But:

$ sudo losetup -d /dev/loop0
$ sudo losetup  /dev/loop0 sda.dd.img
$ sudo fdisk -l  /dev/loop0

Disk /dev/loop0: 82.3 GB, 82348277760 bytes
255 heads, 63 sectors/track, 10011 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x01890189

       Device Boot      Start         End      Blocks   Id  System
/dev/loop0p1   *           1       10010    80405293+   7  HPFS/NTFS
$

/dev/loop0p1 seems inaccessible to me.

Really, any suggestions on how to access this "virtual partition"  
would be great. Oh, I've also tried to run ntfsclone on it, because  
that can produce images which can be loopback mounted (as per `man  
ntfsclone`) but again, ntfsclone need to be pointed at a partition of  
a hard-drive in order to produce the loopback-mountable image in the  
first place.

Any thoughts?

Stroller.