[OE-core] [PATCH 1/1] kernel-grub.bbclass: 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 | 79 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 79 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..21fcabe
--- /dev/null
+++ b/meta/classes/kernel-grub.bbclass
@@ -0,0 +1,79 @@
+#
+# 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.
+#
+
+pkg_preinst_kernel-image_append () {
+	if [ -z "$D" ]; then
+		# Parsing confliction
+		[ -f /boot/grub/menu.list ] && grubcfg="/boot/grub/menu.list"
+		[ -f /boot/grub/grub.cfg ] && grubcfg="/boot/grub/grub.cfg"
+		if [ -n "$grubcfg" ]; then
+			# Dereference symlink to avoid confliction with new kernel name.
+			if grep -q "/${KERNEL_IMAGETYPE} root=" $grubcfg; then
+				kimage=`realpath /boot/${KERNEL_IMAGETYPE}`;
+				sed -i "s#${KERNEL_IMAGETYPE} root=#${kimage##*/} root=#" $grubcfg
+			fi
+
+			# Rename old kernel if it conflicts with new kernel name.
+			if grep -q "/${KERNEL_IMAGETYPE}-${KERNEL_VERSION} root=" $grubcfg; then
+				timestamp=`date +%s`
+				kimage="/boot/${KERNEL_IMAGETYPE}-${KERNEL_VERSION}-$timestamp-back"
+				sed -i "s#${KERNEL_IMAGETYPE}-${KERNEL_VERSION} root=#${kimage##*/} root=#" $grubcfg
+				mv /boot/${KERNEL_IMAGETYPE}-${KERNEL_VERSION} $kimage
+			fi
+		fi
+	fi
+}
+
+pkg_postinst_kernel-image_prepend () {
+	get_new_grub_cfg() {
+		title="Update ${KERNEL_IMAGETYPE}-${KERNEL_VERSION}-${PV}"
+		if [ -f /boot/grub/grub.cfg ]; then
+			rootfs=`grep " *linux [^ ].* root=" /boot/grub/grub.cfg -m 1 | \
+				 sed "s# *linux [^ ].* root=#    linux /${KERNEL_IMAGETYPE}-${KERNEL_VERSION} root=#"`
+
+			echo "menuentry \"$title\" {"
+			echo "    set root=(hd0,1)"
+			echo "$rootfs"
+			echo "}"
+		elif [ -f /boot/grub/menu.list ] ; then
+			rootfs=`grep "kernel [^ ].* root=" /boot/grub/menu.list -m 1 | \
+				 sed "s#kernel [^ ].* root=#kernel /${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() {
+		if [ -f /boot/grub/grub.cfg ]; then
+			cat /boot/grub/grub.cfg
+		elif [ -f /boot/grub/menu.list ] ; then
+			cat /boot/grub/menu.list | sed -e '/^default/d' -e '/^timeout/d'
+		fi
+	}
+
+	if [ -z "$D" ]; then
+		[ -f /boot/grub/menu.list ] && grubcfg="/boot/grub/menu.list"
+		[ -f /boot/grub/grub.cfg ] && grubcfg="/boot/grub/grub.cfg"
+		if [ -n "$grubcfg" ]; then
+			grubcfgtmp="$grubcfg.tmp"
+			get_new_grub_cfg  > $grubcfgtmp
+			get_old_grub_cfg >> $grubcfgtmp
+			mv $grubcfgtmp $grubcfg
+			echo "Caution! Update kernel may affect kernel-module!"
+		fi
+	fi
+}
+
-- 
1.8.1.2