debug: add notes about how to enable debug for shimv2
The containerd's debug option will determine whether
the kata's log forared to containerd's log pipe or
not.
Fixes:#596
* [Check hardware requirements](#check-hardware-requirements)
* [Configure to use initrd or rootfs image](#configure-to-use-initrd-or-rootfs-image)
* [Enable full debug](#enable-full-debug)
+ * [debug logs and shimv2](#debug-logs-and-shimv2)
* [journald rate limiting](#journald-rate-limiting)
* [systemd-journald suppressing messages](#systemd-journald-suppressing-messages)
* [Disabling systemd-journald rate limiting](#disabling-systemd-journald-rate-limiting)
@@ -141,6 +142,21 @@ $ sudo sed -i -e 's/^# *\(enable_debug\).*=.*$/\1 = true/g' /etc/kata-containers
$ sudo sed -i -e 's/^kernel_params = "\(.*\)"/kernel_params = "\1 agent.log=debug initcall_debug"/g' /etc/kata-containers/configuration.toml
```
+### debug logs and shimv2
+
+If you are using `containerd` and Kata shimv2 to launch `kata-runtime`, `containerd`'s debug option
+will determine if the `kata-runtime`'s log is forwarded to `containerd`'s log pipe. If you want to see
+the Kata's log (including the `runtime` and `agent` logs) in the `containerd` log, then you need to
+enable `containerd`'s debug by adding the following to your `containerd`'s config file:
+
+```toml
+[debug]
+ level = "debug"
+```
+
+For much info about the containerd's debug, please see the
+[`containerd` documentation](https://github.com/containerd/containerd/blob/master/docs/getting-started.md).
+
### journald rate limiting
Enabling [full debug](#enable-full-debug) results in the Kata components generating
