core/system/boot/grub2/files/0202-templates-Check-for-EFI-at-runtime-instead-of-config.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Javier Martinez Canillas <javierm@redhat.com>
Date: Tue, 6 Jul 2021 00:38:40 +0200
Subject: [PATCH] templates: Check for EFI at runtime instead of config
 generation time

The 30_uefi-firmware template checks if an OsIndicationsSupported UEFI var
exists and EFI_OS_INDICATIONS_BOOT_TO_FW_UI bit is set, to decide whether
a "fwsetup" menu entry would be added or not to the GRUB menu.

But this has the problem that it will only work if the configuration file
was created on an UEFI machine that supports booting to a firmware UI.

This for example doesn't support creating GRUB config files when executing
on systems that support both UEFI and legacy BIOS booting. Since creating
the config file from legacy BIOS wouldn't allow to access the firmware UI.

To prevent this, make the template to unconditionally create the grub.cfg
snippet but check at runtime if was booted through UEFI to decide if this
entry should be added. That way it won't be added when booting with BIOS.

There's no need to check if EFI_OS_INDICATIONS_BOOT_TO_FW_UI bit is set,
since that's already done by the "fwsetup" command when is executed.

Resolves: rhbz#1823864

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
---
 util/grub.d/30_uefi-firmware.in | 21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/util/grub.d/30_uefi-firmware.in b/util/grub.d/30_uefi-firmware.in
index d344d3883d7..b6041b55e2a 100644
--- a/util/grub.d/30_uefi-firmware.in
+++ b/util/grub.d/30_uefi-firmware.in
@@ -26,19 +26,14 @@ export TEXTDOMAINDIR="@localedir@"
 
 . "$pkgdatadir/grub-mkconfig_lib"
 
-EFI_VARS_DIR=/sys/firmware/efi/efivars
-EFI_GLOBAL_VARIABLE=8be4df61-93ca-11d2-aa0d-00e098032b8c
-OS_INDICATIONS="$EFI_VARS_DIR/OsIndicationsSupported-$EFI_GLOBAL_VARIABLE"
+LABEL="UEFI Firmware Settings"
 
-if [ -e "$OS_INDICATIONS" ] && \
-   [ "$(( $(printf 0x%x \'"$(cat $OS_INDICATIONS | cut -b5)"\') & 1 ))" = 1 ]; then
-  LABEL="UEFI Firmware Settings"
+gettext_printf "Adding boot menu entry for UEFI Firmware Settings ...\n" >&2
 
-  gettext_printf "Adding boot menu entry for UEFI Firmware Settings ...\n" >&2
-
-  cat << EOF
-menuentry '$LABEL' \$menuentry_id_option 'uefi-firmware' {
-	fwsetup
-}
-EOF
+cat << EOF
+if [ "\$grub_platform" = "efi" ]; then
+	menuentry '$LABEL' \$menuentry_id_option 'uefi-firmware' {
+		fwsetup
+	}
 fi
+EOF