Added Kernel page back in

Author: craigloewen-msft

.openpublishing.redirection.json

@@ -35,11 +35,6 @@
       "redirect_url": "compare-versions#whats-new-in-wsl-2",
       "redirect_document_id": false
     },
-    {
-      "source_path": "wsl/wsl2-kernel.md",
-      "redirect_url": "install-win10#step-4---download-the-linux-kernel-update-package",
-      "redirect_document_id": false
-    },
     {
       "source_path": "wsl/wsl2-index.md",
       "redirect_url": "compare-versions#whats-new-in-wsl-2",

WSL/wsl2-kernel.md

@@ -0,0 +1,57 @@
+---
+title: Updating the WSL 2 Linux kernel
+description: Instructions on how to update your WSL 2 Linux kernel manually
+keywords: wsl, windows, linux kernel, windows subsystem for linux, kernel
+ms.date: 03/12/2020
+ms.topic: article
+ms.localizationpriority: high
+---
+
+# Updating the WSL 2 Linux kernel
+
+To manually update the Linux kernel inside of WSL 2 please follow these steps.
+
+> [!NOTE] 
+> If the installer can't find WSL 1, right-click the Linux kernel update installer and press "Uninstall", then rerun the installer.
+
+## Download the Linux kernel update package
+
+Please [download the latest WSL2 Linux kernel](https://wslstorestorage.blob.core.windows.net/wslblob/wsl_update_x64.msi) update package for x64 machines.
+
+> [!NOTE]
+> If you're using an ARM64 machine, please download the [ARM64 package](https://wslstorestorage.blob.core.windows.net/wslblob/wsl_update_arm64.msi) instead.
+
+## Install the Linux kernel update package
+
+To install the Linux kernel update package:
+
+  1. Run the update package downloaded in the previous step.
+
+  2. You will be prompted for elevated permissions, select ‘yes’ to approve this installation.
+
+  3. Once the installation is complete, you are ready to begin using WSL2!
+
+## 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 Subsystem 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. Install the Linux kernel manually following the instructions on this page.
+2. Uninstall the MSI from 'Add or Remove Programs', and install it again.