[coLinux-users] How to access a logical partition

[Harald W. <hwe...@gm...>]

Hello,

How can logical hard disk partitions be accessed within a colinux
environment?

The hard disk partition is like:

Disk /dev/hda: 400.0 GB, 400088457216 bytes
255 heads, 63 sectors/track, 48641 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/hda1   *           1        5099    40957686    7  HPFS/NTFS
/dev/hda2            5100       20397   122881185    7  HPFS/NTFS
/dev/hda3           20398       21856    11719417+  83  Linux
/dev/hda4           21857       48641   215150512+   5  Extended
/dev/hda5           21857       28543    53713296   8e  Linux LVM
/dev/hda6           28544       35230    53713296   8e  Linux LVM
/dev/hda7           35231       41917    53713296   8e  Linux LVM
/dev/hda8           41918       48641    54010498+  8e  Linux LVM

hda1 and hda2 are Windows XP Home C: and D: .
hda3 is the root partition of a Linux installation (Debian 4.0).
hda5 contains an LV group with LVs for swap and /home.

I use the coLinux Snapshot 20080425 with the kernel and modules
version 2.6.22.18-co-0.8.0 as provided by Henry Nestler. The basic
configuration is not special:

mem=256
kernel=vmlinux
root=/dev/cobd0 ro
cobd0=d:\coLinux\system.img
eth0=pcap-bridge,"LAN-Verbindung"

system.img contains a minimal Debian 4.0 installation.

When trying to access the linux partitions under colinux like:

cobd1=\Device\Harddisk0\Partition3
cobd2=\Device\Harddisk0\Partition4
cobd3=\Device\Harddisk0\Partition5
cobd4=\Device\Harddisk0\Partition6
cobd5=\Device\Harddisk0\Partition7

only the primary partition 3 (cobd1) is effectively visible under coLinux.
The logical partitions cannot be accessed:

colinux:~# cat /dev/cobd2
cat: /dev/cobd2: No such device
colinux:~# ls -l /dev/cobd2
brw-rw---- 1 root disk 117, 2 May 18 01:13 /dev/cobd2

According to the output of "dd --list" under Windows,
[see http://uranus.it.swin.edu.au/~jn/linux/rawwrite/dd.htm ]
the partitions should well exist:

[...]
\\?\Device\Harddisk0\Partition0
  link to \\?\Device\Harddisk0\DR0
  Fixed hard disk media. Block size = 512
  size is 400088457216 bytes
\\?\Device\Harddisk0\Partition1
  link to \\?\Device\HarddiskVolume1
\\?\Device\Harddisk0\Partition2
  link to \\?\Device\HarddiskVolume2
\\?\Device\Harddisk0\Partition3
  link to \\?\Device\HarddiskVolume3
  Fixed hard disk media. Block size = 512
  size is 12000683520 bytes
\\?\Device\Harddisk0\Partition4
  link to \\?\Device\HarddiskVolume4
  size is 55002415104 bytes
\\?\Device\Harddisk0\Partition5
  link to \\?\Device\HarddiskVolume5
  size is 55002415104 bytes
\\?\Device\Harddisk0\Partition6
  link to \\?\Device\HarddiskVolume6
  size is 55002415104 bytes
\\?\Device\Harddisk0\Partition7
  link to \\?\Device\HarddiskVolume7
  size is 55306750464 bytes
[...]

Is there a way to access the partitions under coLinux?


I also tried to access the whole hard disk under coLinux:

cobd1=\Device\Harddisk0\Partition0
alias hda=:cobd1

The entire hard disk seems to be visible under coLinux now.
fdisk -l , or partprobe -d -s work fine:

colinux:~# partprobe -d -s
/dev/hda: msdos partitions 1 2 3 4 <5 6 7 8>
/dev/cobd1: msdos partitions 1 2 3 4 <5 6 7 8>

However, the partitions themselves are not present. Even partprobe is not
able to communicate the partitions to the kernel:

debian:~# partprobe -s
Error: Error informing the kernel about modifications to partition /dev/hda1 -- Invalid argument.  This means Linux won't know about any changes you made to /dev/hda1 until you reboot -- so you shouldn't mount it or use it in any way before rebooting.
Error: Error informing the kernel about modifications to partition /dev/hda2 -- Invalid argument.  This means Linux won't know about any changes you made to /dev/hda2 until you reboot -- so you shouldn't mount it or use it in any way before rebooting.
[...]

Finally, I'd like to try to access the locical partitions via the
losetup command with --offset option. But the loop module is not present
within the kernel/modules provided by Henry.

Is there a reason why loop is ommitted? Would it be possible to access
the locical partitions using loop with offset?

Regards,
Harald