Looking at Knoppix 3.8

Matt Zimmerman mdz at ubuntu.com
Mon Mar 14 20:30:32 CST 2005

On Tue, Mar 15, 2005 at 01:13:56PM +1100, Jeff Waugh wrote:

> <quote who="Matthias Klose">
> > highlights are unionfs, a file system mounted rw over the ro file system
> > on the CD, so you can install additional packages, change configs, etc.
> > many options to manually configure hardware.
> We should probably make a bigger deal about the hoary LiveCD's capability to
> do this, using standard components of the Linux kernel rather than new code.

Bearing in mind that I'll gleefully switch casper to use a VFS-level
solution, the instant that there is a viable one, since it would be much
more memory-efficient. :-)  "viable" here means that people in the know in
the kernel community don't run in the other direction when they hear about
it.  Al Viro seems to be the only person who has talked about implementing
this, who I actually believe has a handle on the subtle kernel issues
involved, but he doesn't seem to have published anything in this regard for
a long time.

It looks like this is the one Knoppix chose:


and it doesn't seem to have even been discussed on LKML.

(yes, there's even more than one implementation called 'unionfs')

It wouldn't be a bad idea to implement support for unionfs in casper for
Hoary+1, and allow the overlay method to be chosen at runtime, as a proof of
concept (and because we could very well transition to something else in the

 - mdz

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