We ended up writing some hilariously crappy workarounds for Linux to prevent this kind of thing, where firmware fails to boot if the UEFI variable store is too full. We check whether the write would leave under 5KB of free space (as reported by the firmware), and refuse the write if it would. Easy! Except some firmware would never actually increase the available space count if a variable was deleted, so after a while we'd just never be able to write any more variables

I can't remember how I figured this out, but the affected machines would trigger garbage collection if we tried to create a variable bigger than the available space, so Linux just tries to create a giant variable and then deletes it again to force the firmware to actually update the free space counter

Fucking computers, man