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My subscription to debian-boot doesn't seem to have been processed yet,
and I've been having various DNS problems, so I'm going to respond to both
Adam's and Joey's messages here (because I didn't get Joey's message at
all).
Adam Di Carlo writes
> Joey Hess <joeyh@debian.org> writes:
>
> > > Is it feasible to perform an installation under these conditions, if
> > > we had, say, base2_1.tgz or base2_2.tgz (plus the contents of the
> > > appropriate drivers disk) available somewhere on the CD-ROM?
> >
> > I think it is, though it's going to be quite hackish.
> >
> > It's not too hard to get from just base2_1.tgz to a chrooted Debian system
> > on any linux platform. You just unpack it, twiddle a comple of files that
> > the normal install modifies (like I think some files under /root, and in
> > your case things like /etc/timezone, and /etc/init.d/network.)
> >
> > You can chroot into the base debian system at this point and it's basically
> > a complete debian system. Then you have to make it bootable. This will
> > involve pulling apart drv1440.bin, getting the tarball inside it that
> > contains kernel modules, and installing it into the appropriate place, then
> > pulling apart resc1440.bin and getting the kernel image from it and
> > installing that, then possibly setting up LILO.
Sounds like writing a little installer of our own. :-)
I guess we can write a Debian installer, though not for this version, which
is going out for final testing and maybe manufacturing this week.
I wrote to you (Joey) about slink-and-a-half because I was still hoping that
we might be able to use the standard Debian installer, with various hacks
to exec the official Debian rescue system's init from within our init, if
only we could get the kernel module version problem fixed.
> It would pretty much be trivial to adapt the scripts which make the
> base system to add in, say, kernel images and modules, etc.
We wouldn't need that for our purposes.
> > tar that up to put on the CD, and extract that onto your target system, and
> > finish by fixing up lilo.
>
> This doesn't seem to be what he wants -- as I understand it, we're
> talking about a live bootable filesystem.
Joey is right: we already have a working live bootable filesystem, which
is the main purpose of our CD (for use as a rescue system). That's not a
Debian system, although we did use some things from Debian. However, we
wanted to add as a new feature the ability to install, from the CD, a
regular Debian base system onto a hard drive.
> I wish someone would elucidate what all is required to have a live
> bootable filesystem on a CD... then I could do a better job evaluating
> if boot-floppies should provide (or help with the providing of) this
> functionality (potato or woody).
The main thing that would be different on the floppies would be an unusual
version of init (which has to locate and mount the CD-ROM). El Torito
doesn't tell you the device name of the CD-ROM drive. :-(
>From there, it isn't too bad, because you can have the entire system on
the CD, and have symlinks to make sure that things appear to be in the
right places.
> For instance, some questions. This is all assuming i386.
I'll tell you what we do for the Bootable Business Card, which is not
necessarily the same as other live CD systems. We're only i386 right
now.
> - do you boot into a 2.88 el torito image?
No, 1.44, because of unconfirmed rumors that some BIOSes don't support
2.88 El Torito images.
> - then do you mount the CD as a RO root, or loop mount a file on
> the CD ?
For the previous version: RO root.
For the new version: cloop (the compressed loopback block device, written
by Rusty Russell, and not yet submitted for the official kernel, but GPLed
source is included on the CD) -- like loopback, but essentially a gzipped
file instead of a straight file.
We expect that cloop will be useful for other people who are making bootable
CD-ROMs in the future, because it really expands the effective capacity of
the CD a lot (if you have uncompressed files of some sort on it). (The
downside is that it requires a kernel module, which means you can only
read the "deep" contents of the CD on a system where you are running a
suitable version of Linux and have root.)
> - how do you deal with writable areas of the disk, like /tmp or /var/run ?
Those are in our initrd.
> - do you use an initrd?
Yes. Ours is currently 10 MB (I think), of which we initially use about 2 MB,
and we never unmount it, leaving about 8 MB writable for the system or for
the user's purposes.
> - are the kernel and modules on the "live filesystem" or the bootable image?
> why?
The kernel is on the bootable image, and modules are on the bootable image,
for disk-space reasons.
This has the annoying problem that we can't support systems which need
special CD-ROM drivers, nor systems which need PCMCIA modules to access
their CD-ROMs. Many installers have fixed this by either using 2.88 El
Torito images or making an extra effort to cram the CD-ROM and PCMCIA
modules onto their 1.44 images. Our particular system only supports "IDE
or PCI SCSI" CD-ROM drives, so we did not need to put any modules onto
the El Torito image at all.
--
Seth David Schoen <schoen@loyalty.org> | And do not say, I will study when I
http://www.loyalty.org/~schoen/ | have leisure; for perhaps you will
http://www.loyalty.org/ (CAF) | not have leisure. -- Pirke Avot 2:5
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