[OE-core] [PATCH 1/1] kernel-grub.bbclass: add a method to install/update for bzImage

[Hongxu Jia]

While installing a rpm to update kernel on a deployed target, it will update
the boot area and the boot menu with the kernel as the priority but allow
you to fall back to the original kernel as well.

- In kernel-image's preinstall scriptlet, it backs up original kernel to avoid
  probable confliction with the new one.
- In kernel-image's postinstall scriptlet, it modify grub's config file to
  updates the new kernel as the boot priority.

[YOCTO #4104]

Signed-off-by: Hongxu Jia <hongxu.jia at windriver.com>
---
 meta/classes/kernel-grub.bbclass | 90 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 90 insertions(+)
 create mode 100644 meta/classes/kernel-grub.bbclass

diff --git a/meta/classes/kernel-grub.bbclass b/meta/classes/kernel-grub.bbclass
new file mode 100644
index 0000000..70564f0
--- /dev/null
+++ b/meta/classes/kernel-grub.bbclass
@@ -0,0 +1,90 @@
+#
+# While installing a rpm to update kernel on a deployed target, it will update
+# the boot area and the boot menu with the kernel as the priority but allow
+# you to fall back to the original kernel as well.
+#
+# - In kernel-image's preinstall scriptlet, it backs up original kernel to avoid
+#   probable confliction with the new one.
+#
+# - In kernel-image's postinstall scriptlet, it modifies grub's config file to
+#   updates the new kernel as the boot priority.
+#
+
+pkg_preinst_kernel-image_append () {
+	# Parsing confliction
+	[ -f "$D/boot/grub/menu.list" ] && grubcfg="$D/boot/grub/menu.list"
+	[ -f "$D/boot/grub/grub.cfg" ] && grubcfg="$D/boot/grub/grub.cfg"
+	if [ -n "$grubcfg" ]; then
+		# Dereference symlink to avoid confliction with new kernel name.
+		if grep -q "/${KERNEL_IMAGETYPE} \+root=" $grubcfg; then
+			if [ -L "$D/boot/${KERNEL_IMAGETYPE}" ]; then
+				kimage=`realpath $D/boot/${KERNEL_IMAGETYPE} 2>/dev/null`
+				if [ -f "$D$kimage" ]; then
+					sed -i "s:${KERNEL_IMAGETYPE} \+root=:${kimage##*/} root=:" $grubcfg
+				fi
+			fi
+		fi
+
+		# Rename old kernel if it conflicts with new kernel name.
+		if grep -q "/${KERNEL_IMAGETYPE}-${KERNEL_VERSION} \+root=" $grubcfg; then
+			if [ -f "$D/boot/${KERNEL_IMAGETYPE}-${KERNEL_VERSION}" ]; then
+				timestamp=`date +%s`
+				kimage="$D/boot/${KERNEL_IMAGETYPE}-${KERNEL_VERSION}-$timestamp-back"
+				sed -i "s:${KERNEL_IMAGETYPE}-${KERNEL_VERSION} \+root=:${kimage##*/} root=:" $grubcfg
+				mv "$D/boot/${KERNEL_IMAGETYPE}-${KERNEL_VERSION}" "$kimage"
+			fi
+		fi
+	fi
+}
+
+pkg_postinst_kernel-image_prepend () {
+	get_new_grub_cfg() {
+		grubcfg="$1"
+		title="Update ${KERNEL_IMAGETYPE}-${KERNEL_VERSION}-${PV}"
+		if [ "${grubcfg##*/}" = "grub.cfg" ]; then
+			rootfs=`grep " *linux \+[^ ]\+ \+root=" $grubcfg -m 1 | \
+				 sed "s# *linux \+[^ ]\+ \+root=#    linux /${KERNEL_IMAGETYPE}-${KERNEL_VERSION} root=#"`
+
+			echo "menuentry \"$title\" {"
+			echo "    set root=(hd0,1)"
+			echo "$rootfs"
+			echo "}"
+		elif [ "${grubcfg##*/}" = "menu.list" ]; then
+			rootfs=`grep "kernel \+[^ ]\+ \+root=" $grubcfg -m 1 | \
+				 sed "s#kernel \+[^ ]\+ \+root=#kernel /${KERNEL_IMAGETYPE}-${KERNEL_VERSION} root=#"`
+
+			echo "default 0"
+			echo "timeout 30"
+			echo "title $title"
+			echo "root  (hd0,0)"
+			echo "$rootfs"
+		fi
+	}
+
+	get_old_grub_cfg() {
+		grubcfg="$1"
+		if [ "${grubcfg##*/}" = "grub.cfg" ]; then
+			cat "$grubcfg"
+		elif [ "${grubcfg##*/}" = "menu.list" ]; then
+			cat "$grubcfg" | sed -e '/^default/d' -e '/^timeout/d'
+		fi
+	}
+
+	if [ -f "$D/boot/grub/grub.cfg" ]; then
+		grubcfg="$D/boot/grub/grub.cfg"
+		old_image=`grep ' *linux \+[^ ]\+ \+root=' -m 1 "$grubcfg" | awk '{print $2}'`
+	elif [ -f "$D/boot/grub/menu.list" ]; then
+		grubcfg="$D/boot/grub/menu.list"
+		old_image=`grep '^kernel \+[^ ]\+ \+root=' -m 1 "$grubcfg" | awk '{print $2}'`
+	fi
+
+	# Don't update grubcfg at first install while old bzImage doesn't exist.
+	if [ -f "$D/boot/$old_image" ]; then
+		grubcfgtmp="$grubcfg.tmp"
+		get_new_grub_cfg "$grubcfg"  > $grubcfgtmp
+		get_old_grub_cfg "$grubcfg" >> $grubcfgtmp
+		mv $grubcfgtmp $grubcfg
+		echo "Caution! Update kernel may affect kernel-module!"
+	fi
+}
+
-- 
1.8.1.2