[SOLVED] Create complete, partitioned card image for an (embedded) Linux

Hi,

first of all: hello together, I'm new to that forum, but not new to Linux & Embedded

My problem:

I want to create a complete image for a CF/sd card (kind of memory card doesn't matter) including all approriate partitions. In my case, I have 3 partitions, boot, an embedded linux and a third one for temporary stuff.
Now I want to create an image file with the size of my CF card, e.g. 1GB.
I don't want to use a CF card for that, so partitioning a CF card, copying the files and using dd afterwards to clone the whole CF-card is not an option.
We already tried that with a shell script, what actually works, but I want to ensure if there is a more common or safe way, and that our approach is not unsafe, error-prone etc.
Roughly, I do the following:
- Create an empty 1GB file with dd /dev/zero -> IMAGE_FILE
- Write the partition table to that image file using sfdisk
- create loop devices for my partitions, e.g.
/sbin/losetup /dev/loop0 IMAGE_FILE
/sbin/losetup /dev/loop1 IMAGE_FILE -o [offset for first partition ...]
etc.
- create file systems, e.g. /sbin/mkfs.ext3 /dev/loop1
- mount the loop devices
- copy files there
- install grub on /dev/loop0
- unmount, cleanup etc.

Is this a common and reilable way? Are there tools supporting this kind of work?

thanks a lot in advance!

sebastian

The only part I'd be worried about is using losetup with offset - have a look at kpartx to do it automatically for you.

Ok, thanks. In fact, kpartx is more comfortable. But currently I face the problem, that it is not deterministic, which loop device it will use for my image file, so I do not know, which to use in the subsequent command. In detail, after the kpartx command, I want to do
/sbin/mkfs.ext3 /dev/mapper/loopXp1 etc.
How to define X before or determine afterwards? Of course I can parse kpartx output with awk ...

thanks and regards,
sebastian

Hi,

with the kpartx approach, I'm facing the problem, that grub installation does not seem to work any more when using losetup if works.
I call grub (0.97, embedded elinos Linux) with --batch in exactly the same way as before:

$GrubBin/grub --batch <<EOT &> grub.log
device (hd0) /dev/loop0
root (hd0,0)
setup (hd0)
quit
EOT

The grub call does not give an error, but the image, copied to a CF card, does not boot any more.

The difference now of course is in the loop device setup. With losetup, I had loop0 and then loop1-3 as partitions. Now I have the /dev/mapper structure from kpartx.

Does anyone have an idea?

Thanks and regards,
Sebastian