Implements qemu debug support

qemu/qemu-kernel.go

@@ -67,6 +67,9 @@ type QemuSystem struct {
 	Cpus   int
 	Memory int
 
+	debug bool
+	gdb   string // tcp::1234
+
 	// Timeout works after Start invocation
 	Timeout         time.Duration
 	KilledByTimeout bool
@@ -184,6 +187,10 @@ func (q *QemuSystem) Start() (err error) {
 		"-netdev", "user,id=n1," + hostfwd,
 	}
 
+	if q.debug {
+		qemuArgs = append(qemuArgs, "-gdb", q.gdb)
+	}
+
 	if q.kernel.InitrdPath != "" {
 		qemuArgs = append(qemuArgs, "-initrd", q.kernel.InitrdPath)
 	}
@@ -338,3 +345,8 @@ func (q *QemuSystem) CopyAndRun(user, path string) (output string, err error) {
 
 	return q.Command(user, "chmod +x "+remotePath+" && "+remotePath)
 }
+
+func (q *QemuSystem) Debug(conn string) {
+	q.debug = true
+	q.gdb = conn
+}

qemu/qemu-kernel_test.go

@@ -299,3 +299,47 @@ func TestQemuSystemRun(t *testing.T) {
 	}
 
 }
+
+func openedPort(port int) bool {
+	conn, err := net.Dial("tcp", fmt.Sprintf(":%d", port))
+	if err != nil {
+		return false
+	}
+	conn.Close()
+	return true
+}
+
+func TestQemuSystemDebug(t *testing.T) {
+	t.Parallel()
+	kernel := Kernel{
+		KernelPath: testConfigVmlinuz,
+		InitrdPath: testConfigInitrd,
+	}
+	q, err := NewQemuSystem(X86_64, kernel, testConfigRootfs)
+	if err != nil {
+		return
+	}
+
+	port := 45256
+
+	q.Debug(fmt.Sprintf("tcp::%d", port))
+
+	if openedPort(port) {
+		t.Fatal("Port opened before qemu starts")
+	}
+
+	if err = q.Start(); err != nil {
+		return
+	}
+	defer q.Stop()
+
+	if !openedPort(port) {
+		t.Fatal("Qemu debug port does not opened")
+	}
+
+	q.Stop()
+
+	if openedPort(port) {
+		t.Fatal("Qemu listens after die")
+	}
+}