Re: [dm-devel] Re: [lvm-devel] dm-crypt - some info, and a few development questions

[Joe Thornber <thornber sistina com>]

On Thu, Jul 17, 2003 at 07:32:33PM +0200, Jon Bendtsen wrote:
> to this mailing list, or the linux kernel development one ?

This list is probably best until you have working code.

> > Spend a day playing with dmsetup, and make sure you really understand
> > how to write target types.  The best way to learn is to try and write
> > a trivial target type, eg. a 'reverse' target that divides the device
> > into chunks and then reverses their order, ie. the first logical 
> chunk > is
> > stored in the last logical chunk of the device.  This should only take
> > you ~150 lines of code (start with dm-linear.c and modify).
> 
> hmm, maybe the map into a file is a more trivial target ?

No, not by a long way.

> Would it be an easy target to write, such that i could play with a 
> dm-loop target before making the dm-crypt?

I wouldn't recommend this unless you are already familiar with the
VFS; I would expect there to be subtle deadlock issues.  I don't think
it helps your development path.

- Joe