Description: Add scripts to support kexec rebots with systemd
	systemd supports kexec reboots natively. To perform kexec
	reboot, one can rely upon systemctl loading the kexec kernel
	image or one must load a kexec kernel image before reboot.
	systemctl supports loading kexec image only on systems that
	support boot loader spec. This patch adds a script that can
	determine the right kernel to load and load it in memory ready
	for kexec.
Author: Khalid Aziz <khalid@debian.org>
Origin: other, Debian addition
Bug: https://bugs.debian.org
Last-Update: 2023-09-28 
---
This patch header follows DEP-3: http://dep.debian.net/deps/dep3/
--- a/Makefile.in
+++ b/Makefile.in
@@ -184,10 +184,11 @@
 
 MAN_PAGES:=$(KEXEC_MANPAGE) $(VMCORE_DMESG_MANPAGE)
 MAN_PAGES+=$(MANDIR)/man8/coldreboot.8
+MAN_PAGES+=$(MANDIR)/man8/kexec-load-kernel.8
 BINARIES_i386:=$(KEXEC_TEST)
 BINARIES_x86_64:=$(KEXEC_TEST)
 BINARIES:=$(KEXEC) $(VMCORE_DMESG) $(BINARIES_$(ARCH))
-SCRIPTS:=$(SBINDIR)/coldreboot
+SCRIPTS:=$(SBINDIR)/coldreboot $(SBINDIR)/kexec-load-kernel
 
 UNINSTALL_KDUMP = $(sbindir)/kdump
 UNINSTALL_KDUMP_MANPAGE = $(mandir)/man8/kdump.8
--- a/kexec/Makefile
+++ b/kexec/Makefile
@@ -107,6 +107,8 @@
 KEXEC_MANPAGE = $(MANDIR)/man8/kexec.8
 KEXEC_COLDREBOOT=$(SBINDIR)/coldreboot
 KEXEC_COLDREBOOT_MANPAGE=$(MANDIR)/man8/coldreboot.8
+KEXEC_LOADKERNEL=$(SBINDIR)/kexec-load-kernel
+KEXEC_LOADKERNEL_MANPAGE=$(MANDIR)/man8/kexec-load-kernel.8
 
 -include $(KEXEC_DEPS)
 
@@ -131,6 +133,15 @@
 	@$(MKDIR) -p     $(MANDIR)/man8
 	cp kexec/coldreboot.8 $(KEXEC_COLDREBOOT_MANPAGE)
 
+$(KEXEC_LOADKERNEL): kexec/kexec-load-kernel
+	@$(MKDIR) -p     $(@D)
+	cp kexec/kexec-load-kernel $(KEXEC_LOADKERNEL)
+	/bin/chmod 755 $(KEXEC_LOADKERNEL)
+
+$(KEXEC_LOADKERNEL_MANPAGE): kexec/kexec-load-kernel.8
+	@$(MKDIR) -p     $(MANDIR)/man8
+	cp kexec/kexec-load-kernel.8 $(KEXEC_LOADKERNEL_MANPAGE)
+
 echo::
 	@echo "KEXEC_SRCS $(KEXEC_SRCS)"
 	@echo "KEXEC_DEPS $(KEXEC_DEPS)"
--- /dev/null
+++ b/kexec/kexec-load-kernel
@@ -0,0 +1,90 @@
+#! /bin/sh
+
+PATH=/sbin:/bin:/usr/sbin:/usr/bin
+NOKEXECFILE=/no-kexec-reboot
+
+. /lib/lsb/init-functions
+
+test -r /etc/default/kexec && . /etc/default/kexec
+if [ -d /etc/default/kexec.d ] ; then
+	for snippet in $(run-parts --list /etc/default/kexec.d) ; do
+		. "$snippet"
+	done
+fi
+
+process_grub_entry() {
+	initrd_image=
+	while read command args; do
+		if [ "$command" = "linux" ]; then
+			echo "$args" | while read kernel append; do
+			echo KERNEL_IMAGE=\"${prefix}${kernel}\"
+			echo APPEND=\"${append}\"
+			done
+		elif [ "$command" = "initrd" ]; then
+			initrd_image=${prefix}${args}
+		fi
+	done
+	echo INITRD=\"$initrd_image\"
+}
+
+get_grub_kernel() {
+	test -f /boot/grub/grub.cfg || return
+	local prefix
+	mountpoint -q /boot && prefix=/boot || prefix=
+	data=$(cat /boot/grub/grub.cfg)
+
+	default=$(echo "$data" | awk '/set default/ {print $2}' | cut -d'"' -f2 | tail -1)
+	if [ "$default" = '${saved_entry}' ]; then
+		default=$(sed -ne 's/^saved_entry=//p' /boot/grub/grubenv)
+	fi
+	if [ -z "$default" ]; then
+		default=0
+	fi
+	start_offset=$((default + 1))
+	end_offset=$((default + 2))
+
+	# grub entries start with "menuentry" commands.  Get the line
+	# numbers that surround the first entry
+	offsets=$(echo "$data" | grep -n '^[[:space:]]*menuentry[[:space:]]' | cut -d: -f1)
+	begin=$(echo "$offsets" | tail -n+$start_offset | head -n1)
+	end=$(echo "$offsets" | tail -n+$end_offset | head -n1)
+
+	# If this is the last entry, we need to read to the end of the file
+	# or to the end of boot entry section
+	if [ -z "$end" ]; then
+		numlines=$(echo "$data" | tail --lines=+$begin | grep -n "^### END" | head -1 | cut -d: -f1)
+		end=$((begin + numlines - 1))
+	fi
+
+	length=$((end - begin))
+	entry=$(echo "$data" | tail -n+$begin | head -n$length)
+	eval $(echo "$entry" | process_grub_entry)
+}
+
+load_kernel () {
+	test -x /sbin/kexec || exit 0
+	test "x`cat /sys/kernel/kexec_loaded`y" = "x1y" && exit 0
+
+	if [ -f $NOKEXECFILE ]
+	then
+		/bin/rm -f $NOKEXECFILE
+		exit 0
+	fi
+
+	test "$USE_GRUB_CONFIG" = "true" && get_grub_kernel
+
+	REAL_APPEND="$APPEND"
+
+	test -z "$REAL_APPEND" && REAL_APPEND="`cat /proc/cmdline`"
+	echo "Loading new kernel image into memory"
+	if [ -z "$INITRD" ]
+	then
+		/sbin/kexec -l "$KERNEL_IMAGE" --append="$REAL_APPEND"
+	else
+		/sbin/kexec -l "$KERNEL_IMAGE" --initrd="$INITRD" --append="$REAL_APPEND"
+	fi
+	echo "kexec kernel loaded"
+}
+
+load_kernel
+exit 0
--- /dev/null
+++ b/kexec/kexec-load-kernel.8
@@ -0,0 +1,19 @@
+.\" Process this file with
+.\" groff -man -Tascii kexec-load-kernel.8
+.\"
+.TH kexec 8 "April 2006" Linux "User Manuals"
+.SH NAME
+kexec-load-kernel \- Load the default grub kernel into kexec buffer
+.SH SYNOPSIS
+.B /sbin/kexec-load-kernel
+
+.SH DESCRIPTION
+.B kexec-load-kernel
+parses grub configuration file to determine the default grub kernel and
+loads it in kexec buffer if kexec reboot is enabled.
+
+.SH NOTES
+.PP
+.B kexec-load-kernel
+is run just before a kexec reboot to load the new kernel in memory. The
+subsequent call to kexec will result in this kernel to be kexec'd.