Bogon kernel command line options

dankblog! 2022-03-12, 1842 EDT, at the danktower

i was looking at my dmesg output today, wanting to know something about IOMMU, and noticed the following line:

[ 0.015134] Unknown kernel command line parameters "BOOT_IMAGE=/boot/vmlinuz-5.16.13nlb2 mem_encrypt=off intel_iommu=on", will be passed to user space

first off, some basic kernel command line facts:

• there's a man page, of course: kernel-command-line(7). many options are explained in bootparam(7)
• an option is prefixed with modname. if it's intended for a module (whether that code has been built as a module, or built into the kernel)
• options can be specified in modprobe.d(5), but this only works if the code was actually built as a module
• any unrecognized parameter, and any parameter following "--", is passed to init
• parameters containing a "=" go into init's environment
• hyphens and underscores are equivalent

next: "on the effectiveness of nonnull" 2021-11-05