Handle kernel boot options

The 'system.kernel.elevator' and 'system.kernel.isolcpu' options
have been kept for backward compatibility and should be used in new
fashion way with system.kernel.boot_options parameter.

Change-Id: I51f7167b8b8946500df2065ee6b02bcf21809bc9

README.rst

             net.ipv4.tcp_keepalive_time: 30
             net.ipv4.tcp_keepalive_probes: 8
 
+Configure kernel boot options:
+
+.. code-block:: yaml
+
+    linux:
+      system:
+        kernel:
+          boot_options:
+            - elevator=deadline
+            - spectre_v2=off
+            - nopti
+
 
 CPU
 ~~~

linux/system/kernel.sls

 
 {%- if system.kernel is defined %}
 
-{%- if system.kernel.isolcpu is defined or system.kernel.elevator is defined %}
+{%- set kernel_boot_opts = [] %}
+{%- do kernel_boot_opts.append('isolcpus=' ~ system.kernel.isolcpu) if system.kernel.isolcpu is defined %}
+{%- do kernel_boot_opts.append('elevator=' ~ system.kernel.elevator) if system.kernel.elevator is defined %}
+{%- do kernel_boot_opts.extend(system.kernel.boot_options) if system.kernel.boot_options is defined %}
 
+{%- if kernel_boot_opts %}
 include:
   - linux.system.grub
 
-{%- if system.kernel.isolcpu is defined %}
-
-/etc/default/grub.d/90-isolcpu.cfg:
-  file.managed:
-    - contents: 'GRUB_CMDLINE_LINUX_DEFAULT="$GRUB_CMDLINE_LINUX_DEFAULT isolcpus={{ system.kernel.isolcpu }}"'
-    - require:
-      - file: grub_d_directory
-{%- if grains.get('virtual_subtype', None) not in ['Docker', 'LXC'] %} 
-    - watch_in:
-      - cmd: grub_update
-
-{%- endif %}
-{%- endif %}
-
-{%- if system.kernel.elevator is defined %}
-
-/etc/default/grub.d/91-elevator.cfg:
+/etc/default/grub.d/99-custom-settings.cfg:
   file.managed:
-    - contents: 'GRUB_CMDLINE_LINUX_DEFAULT="$GRUB_CMDLINE_LINUX_DEFAULT elevator={{ system.kernel.elevator }}"'
+    - contents: 'GRUB_CMDLINE_LINUX_DEFAULT="$GRUB_CMDLINE_LINUX_DEFAULT {{ kernel_boot_opts|join(' ') }}"'
     - require:
       - file: grub_d_directory
 {%- if grains.get('virtual_subtype', None) not in ['Docker', 'LXC'] %}
     - watch_in:
       - cmd: grub_update
-
-{%- endif %}
 {%- endif %}
-
 {%- endif %}
 
 {%- if system.kernel.version is defined %}

tests/pillar/system.sls

     kernel:
       isolcpu: 1,2,3,4
       elevator: deadline
+      boot_options:
+        - pti=off
+        - spectre_v2=auto
     cgroup:
       group:
         group_1: