Enable libkrun provider to open a debug console

When running with "log-level=debug" and libkrun as machine provider,
spawn a Terminal to execute "krunkit" to enable users to have full
access to the VMs console for debugging purposes.

Users obtain an interactive, text console with scrollback. It's possible
to interact with both the kernel and GRUB2. To obtain even additional
debugging information, users can add "console=hvc0" to the linux kernel
command line through GRUB2 (it may be worth considering extending the
initial configuration of the VM to add that argument by default).

Signed-off-by: Sergio Lopez <slp@redhat.com>

pkg/machine/apple/apple.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"net"
 	"os"
+	"os/exec"
 	"syscall"
 	"time"
 
@@ -275,6 +276,42 @@ func StartGenericAppleVM(mc *vmconfigs.MachineConfig, cmdBinary string, bootload
 
 	logrus.Debugf("helper command-line: %v", cmd.Args)
 
+	if mc.LibKrunHypervisor != nil && logrus.IsLevelEnabled(logrus.DebugLevel) {
+		rtDir, err := mc.RuntimeDir()
+		if err != nil {
+			return nil, nil, err
+		}
+		kdFile, err := rtDir.AppendToNewVMFile("krunkit-debug.sh", nil)
+		if err != nil {
+			return nil, nil, err
+		}
+		f, err := os.Create(kdFile.Path)
+		if err != nil {
+			return nil, nil, err
+		}
+		err = os.Chmod(kdFile.Path, 0744)
+		if err != nil {
+			return nil, nil, err
+		}
+
+		_, err = f.WriteString("#!/bin/sh\nexec ")
+		if err != nil {
+			return nil, nil, err
+		}
+		for _, arg := range cmd.Args {
+			_, err = f.WriteString(fmt.Sprintf("%q ", arg))
+			if err != nil {
+				return nil, nil, err
+			}
+		}
+		err = f.Close()
+		if err != nil {
+			return nil, nil, err
+		}
+
+		cmd = exec.Command("/usr/bin/open", "-Wa", "Terminal", kdFile.Path)
+	}
+
 	if err := cmd.Start(); err != nil {
 		return nil, nil, err
 	}

pkg/machine/apple/vfkit.go

@@ -9,6 +9,7 @@ import (
 	"github.com/containers/podman/v5/pkg/machine/vmconfigs"
 	vfConfig "github.com/crc-org/vfkit/pkg/config"
 	"github.com/crc-org/vfkit/pkg/rest"
+	"github.com/sirupsen/logrus"
 )
 
 func GetDefaultDevices(mc *vmconfigs.MachineConfig) ([]vfConfig.VirtioDevice, *define.VMFile, error) {
@@ -41,7 +42,12 @@ func GetDefaultDevices(mc *vmconfigs.MachineConfig) ([]vfConfig.VirtioDevice, *d
 	if err != nil {
 		return nil, nil, err
 	}
-	devices = append(devices, disk, rng, serial, readyDevice)
+	devices = append(devices, disk, rng, readyDevice)
+	if mc.LibKrunHypervisor == nil || !logrus.IsLevelEnabled(logrus.DebugLevel) {
+		// If libkrun is the provider and we want to show the debug console,
+		// don't add a virtio serial device to avoid redirecting the output.
+		devices = append(devices, serial)
+	}
 
 	if mc.AppleHypervisor != nil && mc.AppleHypervisor.Vfkit.Rosetta {
 		rosetta := &vfConfig.RosettaShare{