One of the remaining obstacles to running cleanly with root fs mounted read-only has been the mount program, which can only write the mtab file to /etc/. Currently, if /etc/mtab is a symbolic link then mount will not write to it. People have wished (# 94076, #154438) that mount would follow a symlink at /etc/mtab so that it could point somewhere like /run/mtab .
I have written a new patch to make mount do this. The patched program will write mtab through a symlink that leads anywhere but into /proc/ . Lock and temporary mtab files are generated in the same directory as the mtab file. The patched program works properly on my machine. However, because this program is so important it should receive wider testing before I submit it upstream. N.B.: if there turn out to be bugs in the program then you might face the inconvenience of having to boot from a CD-ROM in order to restore the old version of mount. My patch is available via the link at the top of this page: http://panopticon.csustan.edu/thood/readonly-root.html The new version of the mount program (2.12pre) to which it applies is available here: ftp://ftp.win.tue.nl/pub/home/aeb/linux-local/utils/util-linux/ (I built the new [u]mount programs by copying Debian's MCONFIG file out of the Debian util-linux-2.11z source dir and running "./configure" and "make".) Please let me know whether or not you have any problems. -- Thomas Hood