Aqui a> é um artigo do SlashDot falando sobre como rm -rf --no-preserve-root /
bloqueou placas-mãe UEFI devido à remoção de variáveis EFI:
For newer systems utilizing UEFI, running rm -rf / is enough to permanently brick your system. While it's a trivial command to run on Linux systems, Windows and other operating systems are also prone to this issue when using UEFI. The problem comes down to UEFI variables being mounted with read/write permissions and when recursively deleting everything, the UEFI variables get wiped too. Systemd developers have rejected mounting the EFI variables as read-only, since there are valid use-cases for writing to them. Mounting them read-only can also break other applications, so for now there is no good solution to avoid potentially bricking your system, but kernel developers are investigating the issue.
Aqui é um post de um usuário no AskUbuntu detalhando sua experiência com rm -rf --no-preserve-root /
usando sua placa-mãe:
However, upon restart, the monitor was not receiving any input at all. Also, the HDD indicator (or whatever the red light was) wasn't doing one thing. (It was off, in fact.) The fans were working and the DVD drive was, though. (I don't think that there is a PC speaker in there, so if you need some beep error codes, sorry.)
Com a resposta :
Point 1:
Deleting /sys/firmware/efi/efivars/ should thrash your EFI configuration, but in a properly implemented EFI this should be recoverable.
Point 2:
There is some pieces hardware out there with broken/poorly implemented EFI, which will can be permanently bricked by doing standard conform stuff to them. See for example the case where Ubuntu bricked some Samsung laptops by storing additional data in some EFI memory. This behaviour was fine by standard but broke this particular implementation.
Point 3:
Running anything as root that writes to /dev/sda will destroy your partition table and/or filesystems. That's bad especially if you have no backup, but after partitioning, creating new filesystems and reinstalling your OS your machine will work again. So you can recover from it by booting some other media and redo your installation.
Point 4:
Thrashing your EFI is a whole different kind of problem. In the worst case you won't be able to do anything with the machine as it will not get to POST. No booting from an other media, no entering some EFI utility to fix missing stuff. A that point your computer is a really expensive paperweight.
The problem occurs in distributions that run systemd and mount efivarfs writeable (at /sys/firmware/efi/efivars). Systemd needs to write there, so distributions using systemd are affected. However, there seems to be no indication that Upstart systems are affected.