I stumbled upon this when preparing a LiveUSB drive as described in the wiki: https://wiki.gentoo.org/wiki/LiveUSB#Manually_preparing_a_LiveUSB_drive using install-amd64-minimal-20240721T164902Z.iso as ISO image. From console output: >> Looking for the cdrom >> Attempting to mount media: /dev/sda >> Attempting to mount media: /dev/sda1 >> Media found on /dev/sda1 >> Determining root device (trying /dev/sda1) ... >> Root device detected as /dev/sda1! It is then mounted read-write: livecd ~ # grep sda1 /proc/mounts /dev/sda1 /mnt/cdrom vfat rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro 0 0 Now when shutting the system down, readonly remount fails, and the FS ends up with the dirty bit set. In turn, the BIOS (HP) is picky and won't show the USB drive in the boot menu upon the next boot. I'd have expected the file system to be mounted readonly, in the first place. Writing to it is not necessary and isn't even possible when it's iso9660.
