On Sat, Sep 8, 2018 at 7:01 AM, Tom Horsley <horsley1953(a)gmail.com> wrote:
I've been trying to decrypt efibootmgr docs and I've
given up :-).
The firmware situation is awful.
I keep getting the impression you can't examine any
efi boot info other than the one currently active
which you booted from.
There is no firmware state information saved outside of NVRAM. The
gotcha is that efibootmgr doesn't show you everything. It only shows
boot entries and their order. If you look at
$ ls -l /sys/firmware/efi/efivars/
There's a lot of other crap in NVRAM.
What if I want to stick a removable disk into the
system and examine the boot parameters on it?
sudo blkid
then mount any and all FAT12/16/32 volumes
then look inside EFI/BOOT
The firmware will default to booting any OS Loader found in EFI/BOOT
The only state information you'll find there is the OS Loader, not the firmware.
OS Loader = bootloader in UEFI parlance
Any way to point efi tools to a completely separate
non-root disk that just happens to be plugged into
the system?
Nope. There's no firmware state information saved to disk.
--
Chris Murphy