[Fedora-livecd-list] pilgrim livecd work

[David Zeuthen]

On Sat, 2006-09-23 at 17:27 -0500, Jasper Hartline wrote:
> > Does this require network connectivity?
> >   
> Yes, simply invoking Anaconda brings up Anaconda.
> The RPMs can come from the network if it is a LiveCD, and presumably 
> from the network
> or from the DVD if it is a LiveDVD.
> 
> It requires network connectivity in the LiveCD case, yes.. and for the 
> LiveDVD unless
> Fedora Core repository is provided on disc.

I see. Sorry, but I think this is a little backwards, I mean, why
wouldn't I just download the install CD's; it's pretty much the same
amount of traffic. 

Also keep in mind that many consumers of live cd's (typically in poor
countries) have zero network connectivity - all they have is a live cd
that some benevolent organization sent them. Like Ubuntu's ship it.

The approach I have in mind includes just reusing the ext3 file system
we have already prepared and just dd that onto the target installation
block device. That way an install would take very little time and the
only thing you need to make this work is the live cd itself. 

The very reason this will work is that I make almost zero changes to the
live cd rootfs to get the livecd approach going:

 - I don't modify any files

 - I only add a three files
   /etc/init.d/livecd
   /etc/rc5.d/S00livecd
   /etc/udev/rules.d/00-livecd.rules

The reason I can get away with making _only_ these changes is that the
rootfs is rw - the bulk of the work is in the livecd init script. 

So, I think this is a vastly superior approach - what do you think?

> > Nope, but having a rw rootfs is pretty nice for other reasons. 
> >
> > Such as being able to install software while running from the livecd,
> > not having to maintain a magic list of where existing software wants to
> > write to etc. etc.
> >
> >   
> As far as I know UnionFS is the only thing feasible for doing this.

You can use dm-snapshot, see the README.fedora file in the pilgrim
repository here

 http://gitweb.freedesktop.org/?p=users/david/pilgrim.git;a=blob;hb=HEAD;f=README.fedora

specifically the section "LIVECD, HOW IT WORKS" around line 40.

It works extremely well.

See the pilgrim sources for details.

> Bill Nottingham has already stated testing has produced deadlocks and 
> crashes in the simplest of cases.

Yea, unionfs has some issues. Despite that it appears Ubuntu is using
that so I think Bill just used an old version. I haven't bothered to try
myself.

> What were you planning on doing to create a read-write rootfs?

So, pilgrim does this already (as described above) and is in the ISO I
linked to in my first mail to the list. From the live cd, you can easily
do 'yum install xyz' and it just works. You should try it out!

    David