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In A UEFI World, "rm -rf /" Can Brick Your System
efivars are made read only by the kernel. That firmware bug (!) was worked around in the kernel years ago.
https://github.com/torvalds/linux/blob/master/Documentation/filesystems/efivarfs.rst
Specifically in 2016: https://github.com/torvalds/linux/commit/ed8b0de5a33d2a2557dce7f9429dca8cb5bc5879
17 0 Replyuefi is cringe anyway, reject uefi and return to grub in the system firmware
5 0 ReplyFirmware is one step before.
BIOS, UEFI, coreboot, or whatever weird code runs on a Raspberry Pi's GPU to load your system, those are firmwares.
The firmware is what starts your bootloader; grub, BOOTMGR, u-boot, etc
2 0 Replyeven if my grub is in the system eeprom?
1 0 ReplyOh I've never heard of such a setup. But that does muddy the lines a bit, I can see the argument for calling it part of firmware then.
1 0 Replyyeah it's goofy, you can embed grub in coreboot cbfs and load straight into it, skipping the bios/uefi stage. it's a bit difficult to set up (and you need coreboot supported hardware) but when you get it working the boot times become really quick
i just realised though that you can embed Linux into cbfs as well, does that then mean that Linux could be my kernel and firmware at the same time?
1 0 ReplyWow very cool. Thanks for that link, I had no idea coreboot was so flexible!
1 0 Replyyou can embed grub in coreboot cbfs and load straight into it, skipping the bios/uefi stage.
Why would someone do that? *keeps reading*
boot times become really quick
Now I almost want to try it out.
1 0 Reply