[PATCH 05/16] u-boot-script: Become independent of target /etc/fstab

[Jan Kiszka <jan.kiszka@siemens.com>]

From: Jan Kiszka <jan.kiszka@siemens.com>

It's a bit hacky to rely on that file during image creation,
specifically as imagers such as wic may change them. So far we used the
side channel ROOTFS_DEV which needs to be maintained separately from the
commonly used source: the wks file of the target.

This changes the interface of /etc/default/u-boot-script slightly and
reworks how its recipe fills that config file:
 - ROOT_PARTITION variable is added, saving the root partition number
 - KERNEL_ARGS replaces KERNEL_ARGS_APPEND and is supposed to include
   root=<rootdev> from now on
 - do_install derives both the root partition number as well as the root
   device from the wks file, when available
 - in all other (special) cases, u-boot-script should be set by a
   customization package

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
 meta/recipes-bsp/u-boot-script/files/u-boot-script |  7 ++-
 .../u-boot-script/files/update-u-boot-script       | 12 +----
 .../recipes-bsp/u-boot-script/u-boot-script_1.0.bb | 55 ++++++++++++++++++----
 3 files changed, 52 insertions(+), 22 deletions(-)

diff --git a/meta/recipes-bsp/u-boot-script/files/u-boot-script b/meta/recipes-bsp/u-boot-script/files/u-boot-script
index 53cc613..ca31b6d 100644
--- a/meta/recipes-bsp/u-boot-script/files/u-boot-script
+++ b/meta/recipes-bsp/u-boot-script/files/u-boot-script
@@ -1,6 +1,9 @@
-# Arguments to append to kernel command line.
+# Root filesystem partition number
+ROOT_PARTITION="\${distro_bootpart}"
+
+# Arguments for the kernel command line.
 # Make sure to escape $ in u-boot variables, e.g. "\${console}".
-KERNEL_ARGS_APPEND=""
+KERNEL_ARGS=""
 
 # Set to "yes" or "1" to leave out initrd, even if present
 NO_INITRD=""
diff --git a/meta/recipes-bsp/u-boot-script/files/update-u-boot-script b/meta/recipes-bsp/u-boot-script/files/update-u-boot-script
index c12c3ed..c613b13 100755
--- a/meta/recipes-bsp/u-boot-script/files/update-u-boot-script
+++ b/meta/recipes-bsp/u-boot-script/files/update-u-boot-script
@@ -13,23 +13,15 @@ if [ -f /etc/default/u-boot-script ]; then
 	. /etc/default/u-boot-script
 fi
 
-ROOT_DEV=$(egrep '^[^# 	]+[ 	]+/[ 	]' /etc/fstab | awk '{print $1}') \
-	|| true
-
-ROOT_PART="\${distro_bootpart}"
-if [ -n "${ROOT_DEV}" ]; then
-	ROOT_PART=$(echo ${ROOT_DEV} | sed 's/.*[^0-9]\([0-9]*\)$/\1/')
-fi
-
 BOOT_CMD=$(mktemp)
 
 KERNEL_VERSION=$(linux-version list | linux-version sort --reverse | head -1)
 
 echo "${SCRIPT_PREPEND}" >> ${BOOT_CMD}
 
-echo "setenv bootargs root=${ROOT_DEV} ${KERNEL_ARGS_APPEND}" >> ${BOOT_CMD}
+echo "setenv bootargs ${KERNEL_ARGS}" >> ${BOOT_CMD}
 
-echo "load \${devtype} \${devnum}:${ROOT_PART} \${fdt_addr_r}" \
+echo "load \${devtype} \${devnum}:${ROOT_PARTITION} \${fdt_addr_r}" \
      "/usr/lib/linux-image-${KERNEL_VERSION}/\${fdtfile}" >> ${BOOT_CMD}
 echo "load \${devtype} \${devnum}:\${distro_bootpart} \${kernel_addr_r}" \
      "/boot/vmlinuz-${KERNEL_VERSION}" >> ${BOOT_CMD}
diff --git a/meta/recipes-bsp/u-boot-script/u-boot-script_1.0.bb b/meta/recipes-bsp/u-boot-script/u-boot-script_1.0.bb
index da8dca5..8d1ad25 100644
--- a/meta/recipes-bsp/u-boot-script/u-boot-script_1.0.bb
+++ b/meta/recipes-bsp/u-boot-script/u-boot-script_1.0.bb
@@ -16,6 +16,50 @@ SRC_URI = " \
 
 DEBIAN_DEPENDS = "u-boot-tools, linux-image-${KERNEL_NAME}"
 
+# Extract the following information from the wks file and add it to the
+# packaged /etc/default/u-boot-script:
+#  - --append parameters from a bootloader entry
+#  - root partition number
+#  - disk name the root partition is located on
+
+init_config_from_wks() {
+	# Filter out the bootloader line, then grap the argument of --append.
+	# The argument may be quoted, respect that but remove the quotes prior
+	# to assigning the target variable. Will be re-added later.
+	KERNEL_ARGS=$(grep "^bootloader " $1 | \
+		      sed -e 's/.* --append[= ]\(".*"\|[^ $]*\).*/\1/' \
+			  -e 's/\"\(.*\)\"/\1/')
+
+	COUNT=0
+	while read COMMAND MNT OPTIONS; do
+		if [ "${COMMAND}" != part ] ||
+		   echo "${OPTIONS}" | grep -q "\--no-table"; then
+			continue
+		fi
+		COUNT=$(expr ${COUNT} + 1)
+		if [ "${MNT}" = "/" ]; then
+			ROOT_PARTITION=${COUNT}
+			break
+		fi
+	done < $1
+	if [ -n "${ROOT_PARTITION}" ]; then
+		# filter out parameter of --ondisk or --ondrive
+		ROOT=$(echo ${OPTIONS} | \
+		       sed 's/.*--on\(disk\|drive\)[ ]\+\([^ ]\+\) .*/\2/')
+		# anything found?
+		if [ "${ROOT}" != "${OPTIONS}" ]; then
+			# special case: append 'p' to mmcblkN
+			ROOT=$(echo ${ROOT} | sed 's/^\(mmcblk[0-9]\+\)/\1p/')
+
+			KERNEL_ARGS="\"root=/dev/${ROOT}${ROOT_PARTITION} ${KERNEL_ARGS}\""
+		fi
+	fi
+
+	sed -i -e 's|\(^ROOT_PARTITION=\).*|\1\"'"${ROOT_PARTITION}"'\"|' \
+	       -e 's|\(^KERNEL_ARGS=\).*|\1'"${KERNEL_ARGS}"'|' \
+		${WORKDIR}/u-boot-script
+}
+
 do_install() {
 	# Find WKS_FILE specified for the current target.
 	WKS_DIRS=$(dirname $(which wic))/lib/wic/canned-wks
@@ -24,20 +68,11 @@ do_install() {
 	done
 	for DIR in ${WKS_DIRS}; do
 		if [ -f ${DIR}/${WKS_FILE}.wks ]; then
-			WKS_PATH=${DIR}/${WKS_FILE}.wks
+			init_config_from_wks ${DIR}/${WKS_FILE}.wks
 			break
 		fi
 	done
 
-	# Transfer --append parameters from a bootloader entry in the wks file
-	# to the packaged /etc/default/u-boot-script.
-	if [ -n ${WKS_PATH} ]; then
-		APPEND=$(grep "^bootloader " ${WKS_PATH} | \
-			 sed 's/.* --append=\(".*"\|[^ $]*\).*/\1/')
-		sed -i 's|\(^KERNEL_ARGS_APPEND=\).*|\1'"${APPEND}"'|' \
-			${WORKDIR}/u-boot-script
-	fi
-
 	sudo rm -rf ${D}/etc ${D}/usr
 
 	install -v -d ${D}/usr/sbin
-- 
2.16.4