instructions to demo PowerShell Core on Raspbian (#4882)

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@@ -60,6 +60,7 @@ debughandler
 DevOps
 DockerFile
 DockerFiles
+DotNetCore
 DottedScopes
 eBook
 enum
@@ -378,6 +379,14 @@ _script.ps1
 _script.ps1.
 #endregion
 
+#region demos/Raspberry-Pi/README.md Overrides
+ - demos/Raspberry-Pi/README.md
+2.0.x
+2.1.x
+Raspbian
+toolchain
+#endregion
+
 #region demos/rest/README.md Overrides
  - demos/rest/README.md
 rest.ps1

demos/Raspberry-Pi/README.md

@@ -0,0 +1,78 @@
+# Running PowerShell Core 6 on a Raspberry-Pi
+
+## Setup your Pi
+
+Note that CoreCLR (and thus PowerShell Core) will only work on Pi 2 and Pi 3 devices as other devices
+like [Pi Zero](https://github.com/dotnet/coreclr/issues/10605) have an unsupported processor.
+
+Download [Raspbian](https://www.raspberrypi.org/downloads/raspbian/) and follow the [installation instructions](https://www.raspberrypi.org/documentation/installation/installing-images/README.md) to get it onto your Pi.
+
+Once your Pi is up and running, [enable SSH remoting](https://www.raspberrypi.org/documentation/remote-access/ssh/).
+
+## Building PowerShell Core 6 for arm32
+
+We'll need to cross-compile for the Linux arm32 architecture from Ubuntu.
+
+Follow the [Linux instructions to Build PowerShell](https://github.com/PowerShell/PowerShell/blob/master/docs/building/linux.md).
+
+Once your environment is working, you'll need to setup the toolchain for cross compilation:
+
+```powershell
+Start-PSBootstrap -BuildLinuxArm
+```
+
+You can now build PowerShell Core:
+
+```powershell
+Start-PSBuild -Clean -Runtime linux-arm -PSModuleRestore
+```
+
+Note that it's important to do a `-Clean` build because if you previously built for Ubuntu, it won't try to rebuild the native library `pslnative` for arm32.
+
+## Copy the bits to your Pi
+
+Use SSH to copy the bits remotely, replace `yourPi` with the name or IP address of your Pi.
+
+```powershell
+scp -r "$(split-path (Get-PSOutput))/*" pi@yourPi:/home/pi/powershell
+```
+
+## Get latest CoreCLR runtime
+
+We need to get a CoreCLR that fixes a [threading bug](https://github.com/dotnet/coreclr/pull/13922) which is in DotNetCore 2.0.0.
+
+You can do these steps locally on your Pi, but we're using SSH remoting here.
+
+We'll be using the latest [build](https://github.com/dotnet/core-setup#daily-builds) from master which has the fix.
+Note that at the time of authoring these instructions, the 2.0.x servicing build didn't have the necessary fix and the 2.1.x builds may be more unstable.
+
+We'll use `curl` to get the latest DotNetCore runtime.
+
+```bash
+sudo apt install curl
+```
+
+Now we'll download it and unpack it.
+
+```bash
+# Connect to your Pi.
+ssh pi@yourpi
+# We'll make a folder to put latest CoreCLR runtime.
+mkdir dotnet
+cd dotnet
+# Download the latest CoreCLR runtime.
+curl -O https://dotnetcli.blob.core.windows.net/dotnet/Runtime/master/dotnet-runtime-latest-linux-arm.tar.gz
+# Unpack it.
+tar xvf ./dotnet-runtime-latest-linux-arm.tar.gz
+# We're going to overwrite the CoreCLR bits we built with newer ones, replace the version named folder below as appropriate.
+# If you build a newer version of PowerShell Core, you'll need to make sure you get latest CoreCLR runtime otherwise you may hit a segmentation fault.
+cp shared/Microsoft.NetCore.App/2.1.0-preview1-25719-04/* ~/powershell
+```
+
+## Start PowerShell
+
+```bash
+~/powershell/powershell
+```
+
+Note that until arm32 is [fully supported by CoreCLR](https://github.com/dotnet/coreclr/issues/3977), it's not supported by PowerShell Core.