Debug: Enable VM debug console

Enable the VM debug console whenever the VM Kernel debug
is enabled.

Fixes: #559.

Signed-off-by: Manohar Castelino <manohar.r.castelino@intel.com>

Author: mcastelino

config/configuration.toml.in

@@ -36,14 +36,20 @@ disable_block_device_use = @DEFDISABLEBLOCK@
 #enable_swap = true
 
 # Debug changes the default hypervisor and kernel parameters to
-# enable debug output where available.
+# enable debug output where available. Also enable the debug
+# console to be able to connect to the VM for guest debug.
+#
 # Default false
-# these logs can be obtained in the cc-proxy logs  when the 
+#
+# The logs can be obtained in the cc-proxy logs  when the 
 # proxy is set to run in debug mode
 # /usr/libexec/clear-containers/cc-proxy -log debug
 # or by stopping the cc-proxy service and running the cc-proxy 
 # explicitly using the same command line
-# 
+#
+# The console can be accessed typically via
+# /run/virtcontainers/pods/<podid>/console.sock
+#
 #enable_debug = true
 
 [proxy.cc]

create.go

@@ -152,15 +152,23 @@ func create(containerID, bundlePath, console, pidFilePath string, detach bool,
 	return createPIDFile(pidFilePath, process.Pid)
 }
 
-func getKernelParams(containerID string) []vc.Param {
+func getKernelParams(containerID string, runtimeConfig oci.RuntimeConfig) []vc.Param {
+	var systemdTarget string
+
+	if runtimeConfig.HypervisorConfig.Debug {
+		systemdTarget = "clear-containers-debug.target"
+	} else {
+		systemdTarget = "clear-containers.target"
+	}
+
 	return []vc.Param{
 		{
 			Key:   "init",
 			Value: "/usr/lib/systemd/systemd",
 		},
 		{
 			Key:   "systemd.unit",
-			Value: "clear-containers.target",
+			Value: systemdTarget,
 		},
 		{
 			Key:   "systemd.mask",
@@ -179,7 +187,7 @@ func getKernelParams(containerID string) []vc.Param {
 
 func createPod(ociSpec oci.CompatOCISpec, runtimeConfig oci.RuntimeConfig,
 	containerID, bundlePath, console string, disableOutput bool) (vc.Process, error) {
-	ccKernelParams := getKernelParamsFunc(containerID)
+	ccKernelParams := getKernelParamsFunc(containerID, runtimeConfig)
 
 	for _, p := range ccKernelParams {
 		if err := (&runtimeConfig).AddKernelParam(p); err != nil {

docs/debug-kernel.md

@@ -44,3 +44,12 @@ to enable kernel boot logs using the configuration file.
 
    This will result in the `cc-proxy` log being printed on the terminal. This method
    can also be used to capture the logs in a specific `cc-proxy` file.
+
+5. Connect to the Virtual machine console
+
+   If the kernel boots successfully then the virtual machine console can be accessed
+   for further debug.
+
+   ```
+   socat /run/virtcontainers/pods/<pod id>/console.sock
+   ```