rpi-config: Add RPI_CONFIG_STRIP to strip down config.txt

The size of the file config.txt is over 52k, and it may grows over the
versions of the firmware. Even the deprecated options are maintained.

This adds the variable RPI_CONFIG_STRIP to allow the strip down of the
file config.txt to the very bare minimal: it removes the leading white
spaces, the empty lines and the comments.

Signed-off-by: Gilles Doffe <gilles.doffe@rtone.fr>
Signed-off-by: Gaël PORTAY <gael.portay@rtone.fr>

Author: gdoffe

recipes-bsp/bootfiles/rpi-config_git.bb

@@ -37,6 +37,8 @@ WM8960="${@bb.utils.contains("MACHINE_FEATURES", "wm8960", "1", "0", d)}"
 
 GPIO_SHUTDOWN_PIN ??= ""
 
+RPI_CONFIG_STRIP ??= "0"
+
 inherit deploy nopackages
 
 do_deploy() {
@@ -328,10 +330,19 @@ do_deploy:append:raspberrypi3-64() {
 }
 
 do_deploy:append() {
+    # Clean comments, empty lines and leading spaces
+    if [ "${RPI_CONFIG_STRIP}" = "1" ]; then
+        sed -i '/^#/d' $CONFIG
+        sed -i '/^$/d' $CONFIG
+        sed -i 's/^\s*//g' $CONFIG
+    fi
+
+    # Warn about too long lines!
     if grep -q -E '^.{80}.$' ${DEPLOYDIR}/${BOOTFILES_DIR_NAME}/config.txt; then
         bbwarn "config.txt contains lines longer than 80 characters, this is not supported"
     fi
 }
+do_deploy[vardeps] += "${RPI_CONFIG_STRIP}"
 
 addtask deploy before do_build after do_install
 do_deploy[dirs] += "${DEPLOYDIR}/${BOOTFILES_DIR_NAME}"