run: add Xen support

When building Genode on a Linux system running in a Xen Dom0, the 'xen'
run target can run a Genode scenario in a Xen DomU.

Usage: in build/x86_*/etc/build.conf, define:

RUN_OPT = --include boot_dir/$(KERNEL) --include image/iso --include power_on/xen --include log/xen --include power_off/xen

The Xen DomU runs in HVM mode and loads Genode from an ISO image. Serial
log output is printed to the console and graphical output is shown in an
SDL window.

The Xen DomU ist managed using the 'xl' command line tool and it is
possible to add configuration options in the 'xen_args' variable in a run
script. Common options are:

- disabling the graphical output:

  append xen_args { sdl="0" }

- configuring a network device:

  append xen_args { vif=\["model=e1000,mac=02:00:00:00:01:01,bridge=xenbr0"\] }

- configuring USB input devices:

  append xen_args { usbdevice=\["mouse","keyboard"\] }

Note: the 'xl' tool requires super-user permissions and interactive
password input can be troublesome in combination with 'expect' and is not
practical for automatic tests. For this reason, the current implementation
assumes that no password input is needed when running 'sudo xl', which can
be achieved by creating a file '/etc/sudoers.d/xl' with the content
'user ALL=(root) NOPASSWD: /usr/sbin/xl'
(where 'user' is the Linux user name).

Fixes #2504

repos/base/run/log.run

@@ -23,6 +23,7 @@ install_config {
 build_boot_image "core ld.lib.so init test-log"
 
 append qemu_args "-nographic "
+append xen_args  { sdl="0" }
 
 run_genode_until "Test done.*\n" 20
 

repos/dde_linux/run/usb_hid.run

@@ -143,6 +143,7 @@ build_boot_image $boot_modules
 
 append qemu_args "  -usb  -usbdevice mouse -usbdevice keyboard"
 append qemu_args " -device usb-ehci,id=ehci"
+append xen_args  { usbdevice=\["mouse","keyboard"\] }
 
 if { [have_include "power_on/qemu"] || ![get_cmd_switch --autopilot] } { run_genode_until forever }
 

repos/ports/run/lighttpd.run

@@ -47,7 +47,7 @@ append config {
 		<resource name="RAM" quantum="4M"/>
 		<provides><service name="Nic"/></provides>
 	</start>
-	<start name="lighttpd">
+	<start name="lighttpd" caps="200">
 		<resource name="RAM" quantum="1G" />
 		<config>
 			<arg value="lighttpd" />
@@ -123,5 +123,6 @@ append_if [have_spec lan9118] qemu_args " -net nic,model=lan9118 "
 
 append qemu_args " -net user -redir tcp:5555::80 "
 append qemu_args " -nographic -serial mon:stdio "
+append xen_args  { sdl=0\; vif=\["model=e1000,mac=02:00:00:00:01:01,bridge=xenbr0"\] }
 
 run_genode_until forever

tool/run/log/xen

@@ -0,0 +1,38 @@
+##
+# Capture the output of a scenario executed via Xen
+#
+
+source [genode_dir]/tool/run/log.inc
+source [genode_dir]/tool/run/xen.inc
+
+
+proc run_log { wait_for_re timeout_value } {
+	global xen_spawn_id
+	global output_spawn_id
+
+	set output_spawn_id $xen_spawn_id
+
+	set kernel_msg [run_boot_string]
+
+	if {$wait_for_re == "forever"} {
+		set timeout -1
+	} else {
+		set timeout $timeout_value
+	}
+
+	expect {
+		-i $output_spawn_id $kernel_msg { }
+		eof         {
+			puts stderr "Aborting, received EOF"
+			return false
+		}
+		timeout     {
+			puts stderr "Boot process timed out"
+			close
+			return false
+		}
+	}
+
+	wait_for_output $wait_for_re $timeout_value $xen_spawn_id
+	return true
+}

tool/run/power_off/xen

@@ -0,0 +1,3 @@
+proc run_power_off { } {
+	catch { exec sudo xl destroy "genode-hvm" }
+}

tool/run/power_on/xen

@@ -0,0 +1,36 @@
+##
+# Reset the target machine or rather run the scenario as Xen DomU
+#
+
+source [genode_dir]/tool/run/xen.inc
+
+
+##
+# Execute scenario using xl
+#
+proc run_power_on { } {
+	global xen_args
+	global xen_spawn_id
+
+	#
+	# Back out on platforms w/o Xen support
+	#
+	if {![is_xen_available]} { return 0 }
+
+	set xen_base_args { \
+		builder="hvm"\; \
+		name="genode-hvm"\; \
+		cpus="1"\; \
+		memory="512"\; \
+		serial="pty"\; \
+		sdl="1"\; \
+		vnc="0"\; \
+		disk=\["file:[run_dir].iso,hdc:cdrom,r"\]\; \
+		boot="d"\; \
+	}
+
+	eval spawn sudo xl create -c /dev/null $xen_base_args $xen_args
+	set xen_spawn_id $spawn_id
+
+	return true
+}

tool/run/xen.inc

@@ -0,0 +1,31 @@
+set xen_spawn_id    ""
+set xen_args        [get_cmd_arg --xen-args ""]
+
+
+#
+# Enable run scripts to extend 'xen_arg' via 'append' without bothering
+# about the required whitespace in front of the custom arguments.
+#
+append xen_args " "
+
+
+proc xen_args { } {
+	global xen_args
+	return $xen_args
+}
+
+
+##
+# Check whether Xen support is available
+#
+# XXX should by removed in favor of [have_include "exec/xen"]
+#
+proc is_xen_available { } {
+	if {[have_spec linux]} { return false }
+
+	if {![have_spec x86]} {
+		puts stderr "skipping execution because platform is not supported by Xen"
+		return false
+	}
+	return true
+}