I am having a very strange error on an embedded ARM board (poky, kernel 2.6.35). I try to remount / read-only because the device sometimes reboots (hardware watchdog) and I want to avoid file system inconsistencies. I did this in the past with another board without problems, but on this particular system doing a "mount -o remount,ro /" results in a "mount: you must specify the filesystem type" which is not an error I would expect, ever.
"mount" is from util-linux-ng 2.17.2 and I also tried util-linux 2.19.1. The root file system was formatted with "mkfs.ext4 /dev/sdg2 -L rootfs -O extent,^large_file". /etc/mtab is linked to /proc/mtab.