disable video display by default

As of QEMU v5.2, enabling video display has negative impact due to macOS
App Nap: https://gitlab.com/qemu-project/qemu/-/issues/334

Close #29

Signed-off-by: Akihiro Suda <[email protected]>

Author: AkihiroSuda

README.md

@@ -261,6 +261,7 @@ Host * !127.0.0.1
 ### "Hints for debugging other problems?"
 - Inspect logs:
   - `limactl --debug start`
+  - `$HOME/.lima/<INSTANCE>/serial.log`
   - `/var/log/cloud-init-output.log` (inside the guest)
   - `/var/log/cloud-init.log` (inside the guest)
 - Make sure that you aren't mixing up tabs and spaces in the YAML.

docs/internal.md

@@ -11,3 +11,6 @@ An instance directory contains the following files:
 - `qemu-pid`: PID of the QEMU
 - `ssh.sock`: SSH control master socket
 - `ga.sock`: Forwarded to `/run/user/$UID/lima-guestagent.sock`
+- `serial.log`: QEMU serial log, for debugging
+- `serial.sock`: QEMU serial socket, for debugging
+  - Usage: `socat -,echo=0,icanon=0 unix-connect:serial.sock`

pkg/limayaml/default.TEMPLATE.yaml

@@ -51,6 +51,13 @@ firmware:
   # Default: false
   legacyBIOS: false
 
+video:
+  # QEMU display, e.g., "none", "cocoa", "sdl".
+  # As of QEMU v5.2, enabling this is known to have negative impact
+  # on performance on macOS hosts: https://gitlab.com/qemu-project/qemu/-/issues/334
+  # Default: "none"
+  display: "none"
+
 #UNIMPLEMENTED| provision:
 #UNIMPLEMENTED|   # `system` is executed with the root privilege
 #UNIMPLEMENTED|   system: |

pkg/limayaml/defaults.go

@@ -19,6 +19,10 @@ func FillDefault(y *LimaYAML) {
 	if y.Disk == "" {
 		y.Disk = "100GiB"
 	}
+
+	if y.Video.Display == "" {
+		y.Video.Display = "none"
+	}
 }
 
 func resolveArch(s string) Arch {

pkg/limayaml/limayaml.go

@@ -9,6 +9,7 @@ type LimaYAML struct {
 	Mounts   []Mount  `yaml:"mounts,omitempty"`
 	SSH      SSH      `yaml:"ssh,omitempty"` // REQUIRED (FIXME)
 	Firmware Firmware `yaml:"firmware,omitempty"`
+	Video    Video    `yaml:"video,omitempty"`
 }
 
 type Arch = string
@@ -37,3 +38,8 @@ type Firmware struct {
 	// LegacyBIOS is ignored for aarch64.
 	LegacyBIOS bool `yaml:"legacyBIOS,omitempty"`
 }
+
+type Video struct {
+	// Display is a QEMU display string
+	Display string `yaml:"display,omitempty"`
+}

pkg/qemu/qemu.go

@@ -144,7 +144,10 @@ func Cmdline(cfg Config) (string, []string, error) {
 	// virtio-rng-pci acceralates starting up the OS, according to https://wiki.gentoo.org/wiki/QEMU/Options
 	args = append(args, "-device", "virtio-rng-pci")
 
-	// Misc devices
+	// Graphics
+	if y.Video.Display != "" {
+		args = append(args, "-display", y.Video.Display)
+	}
 	switch y.Arch {
 	case limayaml.X8664:
 		args = append(args, "-device", "virtio-vga")
@@ -157,8 +160,23 @@ func Cmdline(cfg Config) (string, []string, error) {
 		args = append(args, "-device", "usb-kbd")
 		args = append(args, "-device", "usb-mouse")
 	}
+
+	// Parallel
 	args = append(args, "-parallel", "none")
 
+	// Serial
+	serialSock := filepath.Join(cfg.InstanceDir, "serial.sock")
+	if err := os.RemoveAll(serialSock); err != nil {
+		return "", nil, err
+	}
+	serialLog := filepath.Join(cfg.InstanceDir, "serial.log")
+	if err := os.RemoveAll(serialLog); err != nil {
+		return "", nil, err
+	}
+	const serialChardev = "char-serial"
+	args = append(args, "-chardev", fmt.Sprintf("socket,id=%s,path=%s,server,nowait,logfile=%s", serialChardev, serialSock, serialLog))
+	args = append(args, "-serial", "chardev:"+serialChardev)
+
 	// We also want to enable vsock and virtfs here, but QEMU does not support vsock and virtfs for macOS hosts
 
 	// QEMU process

pkg/start/start.go

@@ -35,7 +35,7 @@ func Start(ctx context.Context, instName, instDir string, y *limayaml.LimaYAML)
 	qCmd := exec.CommandContext(ctx, qExe, qArgs...)
 	qCmd.Stdout = os.Stdout
 	qCmd.Stderr = os.Stderr
-	logrus.Info("Starting QEMU")
+	logrus.Infof("Starting QEMU (hint: to watch the boot progress, see %q)", filepath.Join(instDir, "serial.log"))
 	logrus.Debugf("qCmd.Args: %v", qCmd.Args)
 	if err := qCmd.Start(); err != nil {
 		return err