Hi all,

I make a LiveCD by my self(not using livecd-tools) which is based on
Fedora 12. And I download an official LiveCD from Fedora website for
study. What I found is the root filesystem of LiveCD is in rw mode. I
noticed that there's an image named osmin.img in LiveOS folder of
Fedora LiveCD ISO image. It seems a LVM snapshot, for further
information I found there's a sentence in Wikipedia says: "Some
Linux-based Live CD systems also use snapshots to simulate read-write
access on a read-only compact disc.". So what I feel confused is how
to make it available in a LiveCD.

Here are steps how do I make my own LiveCD.

1. Create a folder in /tmp called LiveOS.
2. Using yum to create a small base system in LiveOS folder.
3. Modify /etc/sysconfig/readonly-root. READONLY=no, TEMPORARY_STATE=yes
4. Add some folders in /etc/rwtab like /etc, /home, /root.
5. Make a squashfs image by using mksquashfs and rename the image as ext3fs.img.
6. Create a folder in /tmp called iso.
7. Using isolinux as boot loader for the image and copy necessary
files including initramfs and vmlinuz in /tmp/iso/isolinux.
8. Copy the ext3fs.img to /tmp/iso/LiveOS folder.
9. Burning the ISO image.

After these steps the ISO image boots up okay by using qemu. And
/root, /home, /etc are in rw mode, services start okay. But when I
wanna restart or stop the system, it shows

umount: /etc: device is busy.
/etc:
init: rc0 main process (935) killed by KILL signal

Then system hangs.

So my question is what I shall I do for this LiveCD then can make the
root fs in rw mode like official Fedora LiveCD? Do I need to use LVM
snapshot as Wiki said "Some Linux-based Live CD systems also use
snapshots to simulate read-write access on a read-only compact disc."?
If yes, could anyone tell me how to achieve that? I really appreciate
that.

Thanks,

Regards,

Eric

P.S. Please do not just reply "Using livecd-tools them make yourself
easier", I ask questions here for study. Thanks.
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# prevent node from hanging on reboot due to /etc mounts
patch -d /etc/init.d/ -p0 <<\EOF
--- halt.orig	2009-12-05 00:44:29.000000000 +0000
+++ halt	2010-03-24 18:12:36.000000000 +0000
@@ -138,7 +138,7 @@
     $"Unmounting pipe file systems (retry): " \
     -f
 
-LANG=C __umount_loop '$2 ~ /^\/$|^\/proc|^\/dev/{next}
+LANG=C __umount_loop '$2 ~ /^\/$|^\/proc|^\/etc|^\/dev/{next}
 	$3 == "tmpfs" || $3 == "proc" {print $2 ; next}
 	/(loopfs|autofs|nfs|cifs|smbfs|ncpfs|sysfs|^none|^\/dev\/ram|^\/dev\/root$)/ {next}
 	{print $2}' /proc/mounts \
EOF