Improve WSL building documentation

Co-Authored-By: Schmeckl3s <118689460+Schmeckl3s@users.noreply.github.com>
Co-Authored-By: Martin <martin.n.stauber@gmail.com>
Co-Authored-By: MishaBoar <92135099+MishaBoar@users.noreply.github.com>
Co-Authored-By: fultondoge <155709739+FultonDoge@users.noreply.github.com>
Co-Authored-By: edtubbs <ectubbs@gmail.com>

doc/build-windows.md

@@ -31,16 +31,20 @@ To get the bash shell, you must first activate the feature in Windows.
   * Enable 'Windows Subsystem for Linux'
   * Click 'OK' and restart if necessary
 2. Install Ubuntu
-  * Open Microsoft Store and search for "Ubuntu 18.04" or use [this link](https://www.microsoft.com/store/productId/9N9TNGVNDL3Q)
+  * Open Microsoft Store and search for "Ubuntu 20.04" or use [this link](https://apps.microsoft.com/detail/9mttcl66cpxj)
   * Click Install
+  * Reboot (if prompted)
 3. Complete Installation
-  * Open a cmd prompt and type "Ubuntu1804"
+  * Open a cmd prompt and type "Ubuntu2004"
   * Create a new UNIX user account (this is a separate account from your Windows account)
 
 After the bash shell is active, you can follow the instructions below, starting
 with the "Cross-compilation" section. Compiling the 64-bit version is
 recommended but it is possible to compile the 32-bit version.
 
+Some people have reported trouble with these steps and recommend that you apply all relevant Windows updates. Also be sure
+to enable virtualization in your BIOS if necessary.
+
 Cross-compilation
 -------------------
 
@@ -53,29 +57,53 @@ Install the general dependencies. First, ensure your system is updated and has t
     sudo apt update
     sudo apt upgrade
     sudo apt-get install build-essential libtool autotools-dev automake pkg-config bsdmainutils curl git
-    
+
 A host toolchain (`build-essential`) is necessary because some dependency
 packages (such as `protobuf`) need to build host utilities that are used in the
 build process.
 
+## Get the Source Code
+
+To build Dogecoin from source code, you'll need the source code. Either check it out via `git` or download
+a zip file. (Look at the green "<> Code" button on [the Dogecoin GitHub repository](https://github.com/dogecoin/dogecoin/)).
+
+Make sure this code is available in your Ubuntu directory. If you've unzipped a single downloaded file, you may need to change
+the permissions of all extracted files with command like:
+
+  sudo chmod -R <your_username> .
+
+If you've downloaded via `git`, do not use `sudo`. Instead prefer something like:
+
+    cd $HOME
+    git clone https://github.com/dogecoin/dogecoin.git
+    git checkout <branchname>
+
+... where `<branchname>` is the name of the branch you want to build, such as
+"1.14.7-dev" for the unstable branch or "master" for the most recent stable
+release.
+
 ## Building for 64-bit Windows
 
 To build executables for Windows 64-bit, install the following dependencies:
 
     sudo apt-get install g++-mingw-w64-x86-64
 
-For Ubuntu 18.04 and 20.04, set the default mingw32 g++ compiler option to posix:
+For Ubuntu 20.04, set the default mingw32 g++ compiler option to posix:
 
-    sudo update-alternatives --config x86_64-w64-mingw32-g++ 
+    sudo update-alternatives --config x86_64-w64-mingw32-g++
 
 ...Choose the "posix" (vs 'auto' or 'win32') option, and continue.
 
 Note that for WSL v1 the Dogecoin Core source path MUST be somewhere in the default mount file system, for
-example /usr/src/dogecoin, AND not under, for example, /mnt/d/dogecoin. 
+example /usr/src/dogecoin, AND not under, for example, /mnt/d/dogecoin.
 
 If this is not the case the dependency autoconf scripts will fail (silently.)
 This means you cannot use a directory that is located directly on the host Windows file system to perform the build.
 
+To identify your version of WSL, run the command:
+
+  wsl -l -v
+
 If using WSL 1, you'll need to turn off WSL Support for Win32 applications temporarily, or you will get ABI errors and format errors for some .o files.
 
 If using WSL 1 then build using:
@@ -85,27 +113,37 @@ If using WSL 1 then build using:
     cd depends
     make HOST=x86_64-w64-mingw32
     cd ..
-    ./autogen.sh
+    ./autogen.sh # not required when building from release tarball
     CONFIG_SITE=$PWD/depends/x86_64-w64-mingw32/share/config.site ./configure --prefix=/
     make
     sudo bash -c "echo 1 > /proc/sys/fs/binfmt_misc/status" # Re-Enable WSL support for Win32 applications.
-    
+
 If using WSL 2 then you should be able to build just with:
 
+    PATH=$(echo "$PATH" | sed -e 's/:\/mnt.*//g') # strip out problematic Windows %PATH% imported var
     cd depends
     make HOST=x86_64-w64-mingw32
     cd ..
-    ./autogen.sh # not required when building from tarball
+    ./autogen.sh # not required when building from release tarball
     CONFIG_SITE=$PWD/depends/x86_64-w64-mingw32/share/config.site ./configure --prefix=/
     make
-
+
+In either case, be aware that if the first `make` invocation fails, you will see further errors during the `./configure` and second `make` stages. Please
+report any errors with this in mind.
+
+Also be careful using the `-j` flag with any `make` command. People have reported strange compilation errors when doing so.
+
 ## Building for 32-bit Windows
 
 To build executables for Windows 32-bit, install the following dependencies:
 
-    sudo apt-get install g++-mingw-w64-i686 mingw-w64-i686-dev 
+    sudo apt-get install g++-mingw-w64-i686 mingw-w64-i686-dev
+
+Ensure that this toolchain can build for `posix` (else you may have compilation errors for Dogecoin's dependencies):
+
+    sudo update-alternatives --config i686-w64-mingw32-g++
 
-Then build using:
+Choose the `posix` option (instead of `auto` or `win32`), and continue. Then build using:
 
     cd depends
     make HOST=i686-w64-mingw32
@@ -116,7 +154,7 @@ Then build using:
 
 ## Depends system
 
-For further documentation on the depends system see [README.md](../depends/README.md) in the depends directory.
+For further documentation on the depends system see [README.md](../depends/README.md) in the `depends/` directory.
 
 Installation
 -------------