From 8d40bc255e56cd8a2db0cd9703b68216444394ef Mon Sep 17 00:00:00 2001
From: Adphi <philippe.adrien.nousse@gmail.com>
Date: Thu, 18 Jun 2026 15:37:31 +0200
Subject: [PATCH] feat: add mac address support to qemu run command

Signed-off-by: Adphi <philippe.adrien.nousse@gmail.com>
---
 cmd/d2vm/run/qemu.go                    |  3 +++
 docs/content/reference/d2vm_run_qemu.md |  1 +
 pkg/qemu/config.go                      |  7 +++++++
 pkg/qemu/qemu.go                        | 13 ++++++++++---
 4 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/cmd/d2vm/run/qemu.go b/cmd/d2vm/run/qemu.go
index 212d7bc..8b00907 100644
--- a/cmd/d2vm/run/qemu.go
+++ b/cmd/d2vm/run/qemu.go
@@ -32,6 +32,7 @@ var (
 	qemuCmd      string
 	qemuDetached bool
 	networking   string
+	mac          string
 	publishFlags MultipleFlag
 
 	QemuCmd = &cobra.Command{
@@ -80,6 +81,7 @@ func init() {
 
 	// Networking
 	flags.StringVar(&networking, "networking", qemuNetworkingDefault, "Networking mode. Valid options are 'default', 'user', 'bridge[,name]', tap[,name] and 'none'. 'user' uses QEMUs userspace networking. 'bridge' connects to a preexisting bridge. 'tap' uses a prexisting tap device. 'none' disables networking.`")
+	flags.StringVar(&mac, "mac", "", "MAC address for the virtual machine")
 
 	flags.Var(&publishFlags, "publish", "Publish a vm's port(s) to the host (default [])")
 }
@@ -105,6 +107,7 @@ func Qemu(cmd *cobra.Command, args []string) {
 		qemu.WithCPUs(cpus),
 		qemu.WithMemory(mem),
 		qemu.WithNetworking(networking),
+		qemu.WithMAC(mac),
 		qemu.WithStdin(os.Stdin),
 		qemu.WithStdout(os.Stdout),
 		qemu.WithStderr(os.Stderr),
diff --git a/docs/content/reference/d2vm_run_qemu.md b/docs/content/reference/d2vm_run_qemu.md
index 51f220e..8a89504 100644
--- a/docs/content/reference/d2vm_run_qemu.md
+++ b/docs/content/reference/d2vm_run_qemu.md
@@ -17,6 +17,7 @@ d2vm run qemu [options] [image-path] [flags]
       --disk disk               Disk config, may be repeated. [file=]path[,size=1G][,format=qcow2] (default [])
       --gui                     Set qemu to use video output instead of stdio
   -h, --help                    help for qemu
+      --mac string              MAC address for the virtual machine
       --mem uint                Amount of memory in MB (default 1024)
       --networking string       Networking mode. Valid options are 'default', 'user', 'bridge[,name]', tap[,name] and 'none'. 'user' uses QEMUs userspace networking. 'bridge' connects to a preexisting bridge. 'tap' uses a prexisting tap device. 'none' disables networking.` (default "user")
       --publish multiple-flag   Publish a vm's port(s) to the host (default []) (default A multiple flag is a type of flag that can be repeated any number of times)
diff --git a/pkg/qemu/config.go b/pkg/qemu/config.go
index 45862e0..5e63fac 100644
--- a/pkg/qemu/config.go
+++ b/pkg/qemu/config.go
@@ -51,6 +51,7 @@ type config struct {
 	qemuImgPath    string
 	publishedPorts []PublishedPort
 	netdevConfig   string
+	mac            string
 
 	stdin  io.Reader
 	stdout io.Writer
@@ -129,6 +130,12 @@ func WithPublishedPorts(ports ...PublishedPort) Option {
 	}
 }
 
+func WithMAC(mac string) Option {
+	return func(c *config) {
+		c.mac = mac
+	}
+}
+
 func WithStdin(r io.Reader) Option {
 	return func(c *config) {
 		c.stdin = r
diff --git a/pkg/qemu/qemu.go b/pkg/qemu/qemu.go
index 76acb5d..4f724e5 100644
--- a/pkg/qemu/qemu.go
+++ b/pkg/qemu/qemu.go
@@ -135,6 +135,14 @@ func Run(ctx context.Context, path string, opts ...Option) error {
 		return fmt.Errorf("Invalid networking mode: %s", netMode[0])
 	}
 
+	if config.mac != "" {
+		if _, err := net.ParseMAC(config.mac); err != nil {
+			return fmt.Errorf("Invalid MAC address: %s", config.mac)
+		}
+	} else {
+		config.mac = generateMAC().String()
+	}
+
 	if err := config.discoverBinaries(); err != nil {
 		log.Fatal(err)
 	}
@@ -286,11 +294,10 @@ func (c *config) buildQemuCmdline() ([]string, error) {
 	}
 
 	if c.netdevConfig != "" {
-		mac := generateMAC()
 		if c.arch == "s390x" {
-			qemuArgs = append(qemuArgs, "-device", "virtio-net-ccw,netdev=t0,mac="+mac.String())
+			qemuArgs = append(qemuArgs, "-device", "virtio-net-ccw,netdev=t0,mac="+c.mac)
 		} else {
-			qemuArgs = append(qemuArgs, "-device", "virtio-net-pci,netdev=t0,mac="+mac.String())
+			qemuArgs = append(qemuArgs, "-device", "virtio-net-pci,netdev=t0,mac="+c.mac)
 		}
 		forwardings, err := buildQemuForwardings(c.publishedPorts)
 		if err != nil {