selftest: Add early kdump test

This patch will introduce early kdump test.

It reuses the code of nfs kdump test, in order to setup 2 seperated VMs,
one(the client) for trigger the early kdump and crash, the other(the server)
for saving vmcore and check if vmcore exists. In order to minimize the
repetted code, a soft link is made to copy the same server side code.

Signed-off-by: Tao Liu <ltao@redhat.com>
Acked-by: Coiby Xu <coxu@redhat.com>

tests/scripts/testcases/nfs-early-kdump/0-server.sh

@@ -0,0 +1 @@
+../nfs-kdump/0-server.sh

tests/scripts/testcases/nfs-early-kdump/1-client.sh

@@ -0,0 +1,46 @@
+# Executed before VM starts
+on_build() {
+	img_inst_pkg "nfs-utils"
+	img_add_qemu_cmd "-nic socket,connect=127.0.0.1:8010,mac=52:54:00:12:34:57"
+}
+
+on_test() {
+	local boot_count=$(get_test_boot_count)
+	local nfs_server=192.168.77.1
+	local earlykdump_path="/usr/lib/dracut/modules.d/99earlykdump/early-kdump.sh"
+	local tmp_file="/tmp/.tmp-file"
+
+	if [[ ! -f $earlykdump_path ]]; then
+		test_failed "early-kdump.sh not exist!"
+	fi
+
+	if [ $boot_count -eq 1 ]; then
+		cat << EOF > /etc/kdump.conf
+nfs $nfs_server:/srv/nfs
+core_collector makedumpfile -l --message-level 7 -d 31
+final_action poweroff
+EOF
+
+		while ! ping -c 1 $nfs_server -W 1; do
+			sleep 1
+		done
+
+		kdumpctl start \
+			|| test_failed "Failed to start kdump"
+		grubby --update-kernel=ALL --args=rd.earlykdump
+
+		cat << EOF > $tmp_file
+echo 1 > /proc/sys/kernel/sysrq
+echo c > /proc/sysrq-trigger
+EOF
+		sed -i "/early_kdump_load$/r $tmp_file" $earlykdump_path
+		dracut -f --add earlykdump
+		kdumpctl restart \
+			|| test_failed "Failed to start earlykdump"
+
+		sync
+		reboot
+	else
+		test_failed "Unexpected reboot"
+	fi
+}