Have you considered that some firmwares brick if EFI storage is over 50% full? Why not having a file on ESP instead?
This patch series (for me) was motivated by the "gdb: Add more support for
debugging on EFI platforms" patch series, which allowed printing in early
EFI init of the GDB command for properly loading symbols. That approach of
having the functionality be included at compile time was ultimately
rejected. During the discussion of that series, Robbie suggested[1] using
patches by Peter and in the Redhat downstream repo which uses an EFI
variable to store a GRUB env block. Using this, a user could store a
variable in the env block stored in the EFI variable and then have GRUB
load that env block in early init as a way to enable the printing of the
GDB command.
I've taken the original patches by Peter, made more suitable for including
in GRUB, fixed some bugs, and added a minor feature. The first patch, adds
env block loading in early EFI init from the GRUB_ENV EFI variable. The
second patch is included to provide tools for GRUB to set this EFI env
block itself, as opposed to needing to use the method suggested by
Robbie[1], which requires GNU/Linux and the user-space grub2-editenv
utility. Of course, if GRUB is crashing before one can run the
efi-export-env command, then other ways of creating and setting the EFI
envblk variable are necessary. The third patch adds a test which checks the
usability of the commands and the early init loading. And the last patch,
whichvmotivated this series, prints the GDB command string if the GRUB
variable named "enable_earlyinit_gdbinfo" is present and is set to "1", after
the env block is loaded from the GRUB_ENV EFI variable. We might want a
different name for the GRUB variable, I don't really have a preference.
Glenn
[1] https://mail.gnu.org/archive/html/grub-devel/2023-03/msg00072.html
Glenn Washburn (2):
tests: Add efienv_test for testing efi-export-env and efi-load-env
efi: Print GDB command for loading symbols if variable exists
Peter Jones (2):
efi: Load env block from GRUB_ENV EFI variable in early init
efi: Add efi-export-env and efi-load-env commands
Makefile.util.def | 6 ++
docs/grub.texi | 24 +++++
grub-core/Makefile.core.def | 7 ++
grub-core/commands/efi/env.c | 182 +++++++++++++++++++++++++++++++++++
grub-core/kern/efi/efi.c | 3 +
grub-core/kern/efi/init.c | 37 +++++++
grub-core/lib/envblk.c | 43 +++++++++
include/grub/efi/efi.h | 5 +
include/grub/lib/envblk.h | 3 +
tests/efienv_test.in | 57 +++++++++++
10 files changed, 367 insertions(+)
create mode 100644 grub-core/commands/efi/env.c
create mode 100644 tests/efienv_test.in
--
2.34.1
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