Not sure I follow exactly what you're trying to achieve. Images produced by livecd-tools already provide an overlay backed by tmpfs so that /etc, /var and more functionally are writable. However, those changes are not persistent -- if you reboot you're back to the original image.

If you truly want the root fs to be read-only, you might be able to use "mount -o remount,ro" somehow but lots more will likely be broken. You may want to look into the dracut modules that do all the mounting work. In particular, /usr/lib/dracut/modules.d/90dmsquash-live/dmsquash-live-root.sh may be informative. Also worthy of note, dracut is really flexible at letting you wedge things in. I've done this, but developing/testing is a chore considering you need to respin your image to test your new boot hooks.

-- John Florian > -----Original Message----- > From: B. Masuda [mailto:bond.masuda@jlbond.com] > Sent: Tuesday, June 14, 2016 14:10 > To: livecd(a)lists.fedoraproject.org > Subject: [Fedora-livecd-list] help understanding the livecd-creator tool - > i need to make some customizations > > hello, > > i need to create a liveOS DVD with some unique requirements: > > 1) the root file system will be mounted directly off the DVD in read-only > mode > 2) i want to use in-memory disk for only /etc and /var for temporary non- > persistent read-write > > i have practiced using the livecd-creator tool to build a fedora-live- > workstation and centos-7-livecd as a way to get familiar with the tool. it > seems to me that the type of changes I want to make above, are not done in > the kickstart %post section, so I assume it is done as part of the livecd- > creator tool. I've read the README files, but I don't see a detailed > description of how the root file system is configured to mount for the > LiveOS. Looking over the steps described in the README, I *think* I need > to better understand the following steps: > >> Creates a live CD specific initramfs that matches the installed kernel >> Configures the boot loader > Is this the right direction to figure how to accomplish my above stated > goals? If not, please help redirect me. If so, please help me understand > those steps in more detail and how I can modify them to suite my needs. > > thanks in advance... > -- > livecd mailing list > livecd(a)lists.fedoraproject.org > https://lists.fedoraproject.org/admin/lists/livecd@lists.fedoraproject.org -- livecd mailing list livecd(a)lists.fedoraproject.org https://lists.fedoraproject.org/admin/lists/livecd@lists.fedoraproject.org