Description of problem:

On PPC64LE platforms we disable GRUB_ENABLE_BLSCFG=true to force having a completely hardcoded grub2.cfg file with "menuentry" items.

This works fine except the $kernelopts variable is not designed as fallback in case grubenv is broken.

Following snippet is missing:
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------

1. The kernelopts variable should be defined in the grubenv file. But to ensure that menu
2. entries populated from BootLoaderSpec files that use this variable work correctly even
3. without a grubenv file, define a fallback kernelopts variable if this has not been set.
   #
4. The kernelopts variable in the grubenv file can be modified using the grubby tool or by
5. executing the grub2-mkconfig tool. For the latter, the values of the GRUB_CMDLINE_LINUX
6. and GRUB_CMDLINE_LINUX_DEFAULT options from /etc/default/grub file are used to set both
7. the kernelopts variable in the grubenv file and the fallback kernelopts variable.
   if [ -z "${kernelopts}" ]; then
   set kernelopts="..."
   fi
   • • • • • • • 8< ---------------- 8< ---------------- 8< ---------------- 8< --------

Version-Release number of selected component (if applicable):

grub2-2.02-106.el8

How reproducible:

Always

Steps to Reproduce:
1. Generate the file on PPC64le

1. grub2-mkconfig -o /tmp/foo

2. Check content

1. grep kernelopts /tmp/foo
   linux /vmlinuz-4.18.0-147.el8.ppc64le $kernelopts $tuned_params
   linux /vmlinuz-0-rescue-3199ef9eefd840ffb6e94a87b592a6ea $kernelopts

Actual results:

No fallback "if [ -z "${kernelopts}" ]; then ... fi" code

Expected results:

Fallback snippet from /etc/grub.d/10_linux found on x86_64 systems