From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Javier Martinez Canillas <javierm@redhat.com>
Date: Tue, 11 Aug 2020 13:16:45 +0200
Subject: [PATCH] blscfg: Don't hardcode an env var as fallback for the BLS
 options field

If the BLS fragments don't have an options field or if this was set to an
environment variable that was not defined in the grubenv file, the blscfg
module searches for a default_kernelopts variable that is defined in the
grub.cfg file.

But the blscfg module shouldn't hardcode fallbacks variables and instead
this logic should be handled in the GRUB config file itself.

Also, add a comment explaining where the kernelopts variable is supposed
to be defined and what is the process for the user to change its value.

Resolves: rhbz#1850193

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
---
 util/grub.d/10_linux.in | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/util/grub.d/10_linux.in b/util/grub.d/10_linux.in
index 58d185047..48857bb81 100644
--- a/util/grub.d/10_linux.in
+++ b/util/grub.d/10_linux.in
@@ -158,7 +158,17 @@ linux_entry ()
     populate_header_warn
 
     cat << EOF
-set default_kernelopts="root=${linux_root_device_thisversion} ro ${args}"
+# The kernelopts variable should be defined in the grubenv file. But to ensure that menu
+# entries populated from BootLoaderSpec files that use this variable work correctly even
+# without a grubenv file, define a fallback kernelopts variable if this has not been set.
+#
+# The kernelopts variable in the grubenv file can be modified using the grubby tool or by
+# executing the grub2-mkconfig tool. For the latter, the values of the GRUB_CMDLINE_LINUX
+# and GRUB_CMDLINE_LINUX_DEFAULT options from /etc/default/grub file are used to set both
+# the kernelopts variable in the grubenv file and the fallback kernelopts variable.
+if [ -z "\${kernelopts}" ]; then
+  set kernelopts="root=${linux_root_device_thisversion} ro ${args}"
+fi
 
 insmod blscfg
 blscfg