Added new troubleshooting steps (#786)

* Added new troubleshooting steps

Author: craigloewen-msft

WSL/troubleshooting.md

@@ -36,6 +36,41 @@ Lastly, if your issue is related to the Windows Terminal, Windows Console, or th
 
 ## Common issues
 
+### Cannot access WSL files from Windows
+A 9p protocol file server provides the service on the Linux side to allow Windows to access the Linux file system. If you cannot access WSL using `\\wsl$` on Windows, it could be because 9P did not start correctly.
+
+To check this, you can check the start up logs using: `dmesg |grep 9p`, and this will show you any errors. A successfull output looks like the following: 
+
+```
+[    0.363323] 9p: Installing v9fs 9p2000 file system support
+[    0.363336] FS-Cache: Netfs '9p' registered for caching
+[    0.398989] 9pnet: Installing 9P2000 support
+```
+
+Please see [this Github thread](https://github.com/microsoft/wsl/issues/5307) for further discussion on this issue.
+
+### Can't start WSL 2 distro and only see 'WSL 2' in output
+If your display language is not English, then it is possible you are seeing a truncated version of an error text.
+
+```powershell
+C:\Users\me>wsl
+WSL 2
+```
+
+To resolve this issue, please visit `https://aka.ms/wsl2kernel` and install the kernel manually by following the directions on that doc page. 
+
+### Please enable the Virtual Machine Platform Windows feature and ensure virtualization is enabled in the BIOS.
+
+1. Check the [Hyper-V system requirements](https://docs.microsoft.com/windows-server/virtualization/hyper-v/system-requirements-for-hyper-v-on-windows#:~:text=on%20Windows%20Server.-,General%20requirements,the%20processor%20must%20have%20SLAT.)
+2. If your machine is a VM, please enable [nested virtualization](https://docs.microsoft.com/windows/wsl/wsl2-faq#can-i-run-wsl-2-in-a-virtual-machine) manually. Launch powershell with admin, and run: 
+
+```powershell
+Set-VMProcessor -VMName <VMName> -ExposeVirtualizationExtensions $true
+```
+
+3. Please follow guidelines from your PC's manufacturer on how to enable virtualization. In general, this can involve using the system BIOS to ensure that these features are enabled on your CPU. 
+4. Restart your machine after enabling the `Virtual Machine Platform` optional component. 
+
 ### Bash loses network connectivity once connected to a VPN
 
 If after connecting to a VPN on Windows, bash loses network connectivity, try this workaround from within bash. This workaround will allow you to manually override the DNS resolution through `/etc/resolv.conf`.

WSL/wsl2-kernel.md

@@ -34,3 +34,24 @@ To install the Linux kernel update package:
 ## Future plans for updating the WSL2 Linux kernel
 
 For more information, read the article [changes to updating the WSL2 Linux kernel](https://devblogs.microsoft.com/commandline/wsl2-will-be-generally-available-in-windows-10-version-2004), available on the [Windows Command Line Blog](https://aka.ms/cliblog).
+
+## Troubleshooting
+
+### This update only applies to machines with the Windows Subsystem for Linux
+To install MSI kernel, WSL is required and should be enabled first. If it fails, it you will see the message:
+`This update only applies to machines with the Windows Subsytem for Linux`. 
+
+There are three possible reason you see this message:
+
+1. You are still in old version of Windows which doesn't support WSL 2. Please check the [WSL 2 requirements](https://docs.microsoft.com/windows/wsl/install-win10#update-to-wsl-2) and upgrade to use WSL 2. 
+2. `Windows Subsystem for Linux` is not enabled. Please follow the [Windows Subsystem for Linux Installation Guide](https://docs.microsoft.com/windows/wsl/install-win10).
+3. After you enabled `Windows Subsystem for Linux`, a reboot is required to take into effect, please reboot your machine and try again.
+
+### `WSL 2 requires an update to its kernel component. For information please visit https://aka.ms/wsl2kernel`
+
+Each time kernel is missing in %SystemRoot%\system32\lxss\tools\, you may run into the above error.
+
+Here are some possible ways to resolve it:
+
+1. Please install the Linux kernel manually by following the instructions at: https://aka.ms/wsl2kernel
+2. Uninstall the MSI from 'Add or Remove Programs', and install it again