Add display template option for QEMU. Fixes #7675

builder/qemu/builder.go

@@ -298,6 +298,10 @@ type Config struct {
 	// to qemu, allowing it to choose the default. This may be needed when running
 	// under macOS, and getting errors about sdl not being available.
 	UseDefaultDisplay bool `mapstructure:"use_default_display" required:"false"`
+	// What QEMU -display option to use. Defaults to gtk, use none to not pass the
+	// -display option allowing QEMU to choose the default. This may be needed when
+	// running under macOS, and getting errors about sdl not being available.
+	Display string `mapstructure:"display" required:"false"`
 	// The IP address that should be
 	// binded to for VNC. By default packer will use 127.0.0.1 for this. If you
 	// wish to bind to all interfaces use 0.0.0.0.

builder/qemu/step_run.go

@@ -170,8 +170,12 @@ func getCommandArgs(bootDrive string, state multistep.StateBag) ([]string, error
 		}
 	} else {
 		if qemuVersion.GreaterThanOrEqual(v2) {
-			if !config.UseDefaultDisplay {
-				defaultArgs["-display"] = "sdl"
+			if len(config.Display) > 0 {
+				if config.Display != "none" {
+					defaultArgs["-display"] = config.Display
+				}
+			} else if !config.UseDefaultDisplay {
+				defaultArgs["-display"] = "gtk"
 			}
 		} else {
 			ui.Message("WARNING: The version of qemu  on your host doesn't support display mode.\n" +