Arch Linux

Description:

By default, pstore will use efivars as persistent storage. This has the effect of placing "dump" files under /sys/firmware/efi/efivarfs . In certain situations this can fill NVRAM and potentially leave the system unbootable. It can also create issues when installing a bootloader (e.g. GRUB will complain of a lack of space), and will no doubt negatively affect NVRAM lifespan.

The default behaviour can be controlled by the kernel config option CONFIG_EFI_VARS_PSTORE_DEFAULT_DISABLE; this is unset by default in Arch kernels.

With that option enabled, a kernel option can be passed for pstore to use efivar as persistent storage when needed.

Example inclusion in kernel 3.4, https://lore.kernel.org/patchwork/patch/470715/:

"We know that with some firmware implementations writing too much data to UEFI variables can lead to bricking machines. Recent changes attempt to address this issue, but for some it may still be prudent to avoid writing large amounts of data until the solution has been proven on a wide variety of hardware.

"Crash dumps or other data from pstore can potentially be a large data source. Add a pstore_module parameter to efivars to allow disabling its use as a backend for pstore. Also add a config option, CONFIG_EFI_VARS_PSTORE_DEFAULT_DISABLE, to allow setting the default value of this paramter to true (i.e. disabled by default)."

Red Hat/Fedora seem to have enabled that option back in 2013 (https://bugzilla.redhat.com/show_bug.cgi?id=919485, though that might well have changed since).


Additional info:
* linux, linux-zen 5.11.*
* 2014 example of boot loader installation failure: https://bbs.archlinux.org/viewtopic.php?id=182978
* 2021 example of boot loader installation failure: https://forum.garudalinux.org/t/garuda-installation-failed/5507/30

Steps to reproduce:

* Not easily reproducible, can depend on oopses, panics, etc.
* ls /sys/firmware/efi/efivarfs/dump-*