fng-install: Updated post-install scripts

The environmental variable based passing of devicetrees and overlays has
been replaced entirely by a file-based mechanism.
The documentation, comments, and format of the post-install scripts
have been extended and reworked.

recipes-bsp/fng-install/prepare-image/gf-prepare-dt.sh

@@ -25,16 +25,13 @@ mount_bootpartition BOOTFILES_DIR
 
 #========================================================
 
-# ENV Variable DEVICETREE is set from the fng-install script
-# when it was called with --DTB parameter
-#
-if [ -z "$DEVICETREE" ]
-then
 # Read the default devicetree file from the boot partition
 if [ -r "$BOOTFILES_DIR"/devicetree ]
 then
     DEVICETREE_FILE="$( head -n 1 "$BOOTFILES_DIR"/devicetree )"
 else
+    # If no default devicetree is set, detect a valid
+    # devicetree based on the platform
     get_platform PLATFORM
 
     for dtb in "$BOOTFILES_DIR/"*"$PLATFORM.dtb" ; do
@@ -45,9 +42,11 @@ then
         echo "No devicetree found for: $PLATFORM"
         exit 1
     fi
-    fi
-else
-    DEVICETREE_FILE="$DEVICETREE"
+
+    mount -o remount,async "$BOOTFILES_DIR"
+
+    # Mark the selected devicetree as default
+    echo "$DEVICETREE_FILE" > "$BOOTFILES_DIR/devicetree"
 fi
 
 if [ ! -e "$BOOTFILES_DIR/$DEVICETREE_FILE" ]
@@ -56,14 +55,6 @@ then
     exit 1
 fi
 
-mount -o remount,async "$BOOTFILES_DIR"
-
-# Mark the selected devicetree as default
-#
-# Note: Since we are on a fat partition,
-# we use a textfile instead of a link.
-echo "$DEVICETREE_FILE" > "$BOOTFILES_DIR/devicetree"
-
 exit 0
 
 # vim: tabstop=4 expandtab shiftwidth=4 softtabstop=4

recipes-bsp/fng-install/prepare-image/gf-prepare-kernel.sh

@@ -7,18 +7,14 @@
 #               BOOTPARTITION='$TARGET_PARTITION_BOOT' \
 #
 # The script can also be called standalone, or by the fnginstall-postinstallation
-# script in the target OS, to update configurations
+# script in the target OS, to update configurations.
 #
-# This helper script to select the used base kernel and base devicetree
-# and combine those together to linux image
-# In dunfell we currently use the feature to load the devicetree directly
-# after the kernel in the memory by concat both files
+# This helper script loads/detects the active/valid kernel, loads the active
+# devicetree, and appends the devicetree overlays to the active devicetree
+# if applicable.
 #
-# Kernel and devicetree files are detect automatically
-# but may be specified on the commandline
-# After the selection, the result is written to two textfiles
-# 'kernel' and 'devicetree'.
-# When these are found, these values override the autodetection
+# Note: For i.MX6 devices, the kernel and devicetree (including the overlays)
+# are combined into a single file (named linuximage) that is loaded altogether.
 #
 # The files to work on, are selected by a list of known boot partitions
 # from which the first one is selected.
@@ -44,37 +40,31 @@ mount_bootpartition BOOTFILES_DIR
 # Detect active kernel
 #========================================================
 
-# Allows to specify a specific kernel as environment variable
-# Not used currently
-if [ -z "$KERNEL" ]
-then
-    # Read default kernel file from boot partitione
+# Read the active kernel from the boot partition
 if [ -r "$BOOTFILES_DIR"/kernel ]
 then
     KERNEL_FILE="$( head -n 1 "$BOOTFILES_DIR"/kernel )"
 else
-
-        # Mark the currently installed kernel as selected:
-        # (we are on fat, so we use a textfile instead of links):
+    # If no kernel is marked as active, detect a valid kernel
+    # inside the boot partition and mark it as active
     KERNEL_FILE="$( find "$BOOTFILES_DIR" -maxdepth 1 -name "*Image*" \
                     -exec basename {} \; | head -n 1 )"
+
     if [ -z "$KERNEL_FILE" ]
     then
-            echo "Failed to determine the kernel file to use."
+        echo "Failed to determine a valid kernel to be used."
         exit 1
     fi
 
+    # Store the active kernel for later usage
+    echo "$KERNEL_FILE" > "$BOOTFILES_DIR/kernel"
+
+    # Set the active kernel in the boot configuration
     sed -i "$BOOTFILES_DIR/boot.cfg" -e "s|kernel=.*|kernel=$KERNEL_FILE|"
 fi
-else
-    KERNEL_FILE="$KERNEL"
-fi
 
 mount -o remount,async "$BOOTFILES_DIR"
 
-# Store default kernel file for later usage
-echo "$KERNEL_FILE" > "$BOOTFILES_DIR/kernel"
-
 #========================================================
 # Load active devicetree from file and apply overlays
 #========================================================
@@ -84,8 +74,7 @@ DEVICETREE_APPEND_FILE=$DEVICETREE_FILE
 
 # Load the active overlays from the overlays.txt
 if [ -e "$BOOTFILES_DIR/overlays.txt" ]; then
-    DEVICETREE_OVERLAYS_FILE="$( head -n 1 "$BOOTFILES_DIR"/overlays.txt | awk -F '=' '{print $2}' )"
-    DEVICETREE_OVERLAYS="$DEVICETREE_OVERLAYS_FILE $DEVICETREE_OVERLAYS"
+    DEVICETREE_OVERLAYS="$( head -n 1 "$BOOTFILES_DIR"/overlays.txt | awk -F '=' '{print $2}' )"
 fi
 
 # Change into the boot directory and combine the devicetree