I am trying to do the same. My first attempt used a loopback locking device, but I found workarounds for both phases requiring a loopback.
Loop steps
Here is what I am doing ($ 1 is the image file name, $ 2 is the file size):
- create an image file with a zero disk with
dd if=/dev/zero of=$1 bs=512 count=$(($2/512)) - create a partition table with
parted -s $1 mklabel msdos - create a partition with
parted -s $1 "mkpart primary 0% 100%" - attach section to
sudo losetup --find $1 --offset $OFFSET_TO_PARTITION_BYTES - create a file system using mkfs.ext4 with
mkfs.ext4 -I 128 -L BOOT -b 2048 -O ^has_journal /dev/loop0 $SIZE_IN_2048_BLOCKS - mount / dev / loop0
The loop is used because
- In steps 4 and 5, mkfs does not have an offset option, so losetup is used to solve this problem.
- in step 6, mount allows you to use the ext4 driver of the operating system
Looback workarounds
Workaround for steps 4 and 5:
- xmount --in dd --out vdi disk.img mnt /
- vdfuse -f mnt / disk.vdi -r./mnt2
- ./mnt2 will now have two files: EntireDisk and Partition1
- point mkfs.ext4 at./mnt2/Partition1
Solution for work in step 6:
- follow all steps for step 5
- use fuseext2 to install. / mnt 2 / Partition1
Caveat
Caution: ext4 support is not announced in their documentation, and mount attempts come with a warning:
This is experimental code, opening rw a real file system could be dangerous for your data. Please add "-o ro" if you want to open the file system image in read-only mode, or "-o rw+" if you accept the risk to test this module
Update
vdfuse should be able to mount the raw image without xmount, but there is an error that ignores the RAW parameter.
I tracked and fixed the bug with the patch here:
https://bugs.launchpad.net/ubuntu/+source/virtualbox-ose/+bug/1019075