Every so often I have to boot Linux into single-user mode. I do this by waiting for the Grub2 menu, selecting the desired kernel, and pressing 'e'. Then I select the 'linux' statement, add '<space>1' to the end of the line, and boot with <Ctrl-X>.
This still works fine, but since upgrading to Fedora 34 I've noticed that the menu overrides I make in this manner are persistent. That is, if I add "1" to the end of the boot parameters for one boot, "1" will remain in effect until I explicitly remove it: press 'e' from the Grub2 menu, remove "<space>1", and press <Ctrl-X>.
This was rather scary when I first discovered this behavior. Booting into single-user mode without asking to do so is ordinarily associated with a serious system issue.
Was this a deliberate change? If so, where is it documented?
I'm not sure I totally like this change. In some situations, it could be handy to add a kernel parameter using the Grub2 menu and have it stick around from one boot to another, but sometimes the old behavior was good for a one-time "failsafe" change that would be reverted just by doing a normal reboot.
Contents of /etc/default/grub:
GRUB_TIMEOUT=5 GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)" GRUB_DEFAULT=saved GRUB_DISABLE_SUBMENU=true GRUB_TERMINAL_OUTPUT="console" GRUB_CMDLINE_LINUX="rhgb quiet rd.driver.blacklist=nouveau modprobe.blacklist=nouveau nvidia-drm.modeset=1 acpi_enforce_resources=lax" GRUB_DISABLE_RECOVERY="true" GRUB_ENABLE_BLSCFG=true
Thanks, Dave