maintenance of my UEFI variables

smmilut · 2022-09-14 08:52:26

Hello,

Following the recent news article I had issues with the grub-install command. Now it seems solved and my system boots normally, but I have questions about the maintenance of my system.

My motherboard is "ASUSTeK COMPUTER INC. Z97-A Rev 1.xx" with original firmware.

The problem I had

After a system update (pacman -Syu), I tried to apply the steps from the news article, in my case :

# grub-install --target=x86_64-efi --efi-directory=/efi --bootloader-id=GRUB

This failed with the message :

Could not delete variable: No space left on device
grub-install: error: efibootmgr failed to register the boot entry: Block device required.

Apparently the boot entry was deleted but could not be re-created :

# efibootmgr -v
BootCurrent: 0001
Timeout: 1 seconds
BootOrder: 0000,0001
Boot0000* Windows Boot Manager  HD(2,GPT,41f0c4a1-93e2-4e7e-86c8-bbcbd9392e45,0x96800,0x31800)/File(\EFI\MICROSOFT\BOOT\BOOTMGFW.EFI)57494e444f5753000100000088000000780000004200430044004f0042004a004500430054003d007b00390064006500610038003600320063002d0035006300640064002d0034006500370030002d0061006300630031002d006600330032006200330034003400640034003700390035007d00000061000100000010000000040000007fff0400
      dp: 04 01 2a 00 02 00 00 00 00 68 09 00 00 00 00 00 00 18 03 00 00 00 00 00 a1 c4 f0 41 e2 93 7e 4e 86 c8 bb cb d9 39 2e 45 02 02 / 04 04 46 00 5c 00 45 00 46 00 49 00 5c 00 4d 00 49 00 43 00 52 00 4f 00 53 00 4f 00 46 00 54 00 5c 00 42 00 4f 00 4f 00 54 00 5c 00 42 00 4f 00 4f 00 54 00 4d 00 47 00 46 00 57 00 2e 00 45 00 46 00 49 00 00 00 / 7f ff 04 00
    data: 57 49 4e 44 4f 57 53 00 01 00 00 00 88 00 00 00 78 00 00 00 42 00 43 00 44 00 4f 00 42 00 4a 00 45 00 43 00 54 00 3d 00 7b 00 39 00 64 00 65 00 61 00 38 00 36 00 32 00 63 00 2d 00 35 00 63 00 64 00 64 00 2d 00 34 00 65 00 37 00 30 00 2d 00 61 00 63 00 63 00 31 00 2d 00 66 00 33 00 32 00 62 00 33 00 34 00 34 00 64 00 34 00 37 00 39 00 35 00 7d 00 00 00 61 00 01 00 00 00 10 00 00 00 04 00 00 00 7f ff 04 00

The entry for Boot0001 is missing, but it still appears in the BootOrder.

I have more detailed messages (and the message became different) with "--debug" :

# grub-install --target=x86_64-efi --efi-directory=/efi --bootloader-id=GRUB --debug
[...]
grub-install: info: Registering with EFI: distributor = `GRUB', path = `\EFI\GRUB\grubx64.efi', ESP at hostdisk//dev/sdb,gpt2.
grub-install: info: executing efibootmgr --version </dev/null >/dev/null.
grub-install: info: executing modprobe -q efivars.
grub-install: info: executing efibootmgr -c -d /dev/sdb -p 2 -w -L GRUB -l \EFI\GRUB\grubx64.efi.
Could not prepare Boot variable: No space left on device
grub-install: error: efibootmgr failed to register the boot entry: Input/output error.

# efibootmgr --create --disk /dev/sdb --part 2 --write-signature --loader /EFI/GRUB/grubx64.efi --label "GRUB" --verbose
Could not prepare Boot variable: No space left on device
error trace:
 efivarfs.c:445 efivarfs_set_variable(): writing to fd 4 failed: No space left on device
 lib.c:78 _efi_set_variable_mode(): ops->set_variable() failed: No space left on device
 efibootmgr.c:331 make_var(): efi_set_variable failed: No space left on device
 efibootmgr.c:341 make_var(): Could not set variable Boot0001: No space left on device

What I had tried

I didn't find any entry to delete that looked like /sys/firmware/efi/efivars/dump-*
I couldn't manually delete the Boot0001 entry, as it was already deleted :

# efibootmgr --bootnum 1 --delete-bootnum
Could not delete variable: No such file or directory

I tried rebooting a few times, because I read somewhere that it could allow the firmware to do garbage collection on its NVRAM. I am not sure about terminology because I don't understand well the UEFI stuff.

How I solved it

I read the advice and the warning on the wiki and booted the Arch ISO with the kernel parameter "efi_no_storage_paranoia" in order to chroot and successfully complete the steps :

# grub-install --target=x86_64-efi --efi-directory=/efi --bootloader-id=GRUB
# grub-mkconfig -o /boot/grub/grub.cfg

Now my system boots (with the kernel parameter) and all seems fine.

My question

I am worried that something is taking up more and more space for my UEFI variables, and that one day I will boot with "efi_no_storage_paranoia" to fix a similar issue, and end up filling up the whole memory and rendering my motherboard unusable.
Is this a legitimate concern ?
Is there anything I can do to investigate this ?

Arch Linux

#1 2022-09-14 08:52:26