doc: Update for FreeBSD 12.2, add GUI Build Instructions

The current FreeBSD Build documentation is a little outdated and underwhelming. This PR updates the doc to
be more informative. It also adds new instructions for building the GUI and adding support for  descriptor
wallets.

on vasild's recommendation: it is ok to point the user to download db5 which has an active port package
instead of building db4 from the provided script.

Co-authored-by: Vasil Dimov <vd@freebsd.org>

1 files changed, 90 insertions, 22 deletions

diff --git a/doc/build-freebsd.md b/doc/build-freebsd.md
index f48855a344..18ea84c579 100644
--- a/doc/build-freebsd.md
+++ b/doc/build-freebsd.md
@@ -1,59 +1,127 @@
-FreeBSD build guide
-======================
-(updated for FreeBSD 12.0)
+# FreeBSD Build Guide
 
-This guide describes how to build bitcoind and command-line utilities on FreeBSD.
+**Updated for FreeBSD [12.2](https://www.freebsd.org/releases/12.2R/announce.html)**
 
-This guide does not contain instructions for building the GUI.
+This guide describes how to build bitcoind, command-line utilities, and GUI on FreeBSD.
+
+## Dependencies
+
+The following dependencies are **required**:
+
+ Library                                                               | Purpose    | Description
+ ----------------------------------------------------------------------|------------|----------------------
+ [autoconf](https://svnweb.freebsd.org/ports/head/devel/autoconf/)     | Build      | Automatically configure software source code
+ [automake](https://svnweb.freebsd.org/ports/head/devel/automake/)     | Build      | Generate makefile (requires autoconf)
+ [libtool](https://svnweb.freebsd.org/ports/head/devel/libtool/)       | Build      | Shared library support
+ [pkgconf](https://svnweb.freebsd.org/ports/head/devel/pkgconf/)       | Build      | Configure compiler and linker flags
+ [git](https://svnweb.freebsd.org/ports/head/devel/git/)               | Clone      | Version control system
+ [gmake](https://svnweb.freebsd.org/ports/head/devel/gmake/)           | Compile    | Generate executables
+ [boost-libs](https://svnweb.freebsd.org/ports/head/devel/boost-libs/) | Utility    | Library for threading, data structures, etc
+ [libevent](https://svnweb.freebsd.org/ports/head/devel/libevent/)     | Networking | OS independent asynchronous networking
+
+
+The following dependencies are **optional**:
+
+  Library                                                                    | Purpose          | Description
+  ---------------------------------------------------------------------------|------------------|----------------------
+  [db5](https://svnweb.freebsd.org/ports/head/databases/db5/)                | Berkeley DB      | Wallet storage (only needed when wallet enabled)
+  [qt5](https://svnweb.freebsd.org/ports/head/devel/qt5/)                    | GUI              | GUI toolkit (only needed when GUI enabled)
+  [libqrencode](https://svnweb.freebsd.org/ports/head/graphics/libqrencode/) | QR codes in GUI  | Generating QR codes (only needed when GUI enabled)
+  [libzmq4](https://svnweb.freebsd.org/ports/head/net/libzmq4/)              | ZMQ notification | Allows generating ZMQ notifications (requires ZMQ version >= 4.0.0)
+  [sqlite3](https://svnweb.freebsd.org/ports/head/databases/sqlite3/)        | SQLite DB        | Wallet storage (only needed when wallet enabled)
+  [python3](https://svnweb.freebsd.org/ports/head/lang/python3/)             | Testing          | Python Interpreter (only needed when running the test suite)
+
+  See [dependencies.md](dependencies.md) for a complete overview.
 
 ## Preparation
 
-You will need the following dependencies, which can be installed as root via pkg:
+### 1. Install Required Dependencies
+Install the required dependencies the usual way you [install software on FreeBSD](https://www.freebsd.org/doc/en/books/handbook/ports.html) - either with `pkg` or via the Ports collection. The example commands below use `pkg` which is usually run as `root` or via `sudo`. If you want to use `sudo`, and you haven't set it up: [use this guide](http://www.freebsdwiki.net/index.php/Sudo%2C_configuring) to setup `sudo` access on FreeBSD.
 
 ```bash
 pkg install autoconf automake boost-libs git gmake libevent libtool pkgconf
 
+```
+
+### 2. Clone Bitcoin Repo
+Now that `git` and all the required dependencies are installed, let's clone the Bitcoin Core repository to a directory. All build scripts and commands will run from this directory.
+``` bash
 git clone https://github.com/bitcoin/bitcoin.git
 ```
 
-In order to run the test suite (recommended), you will need to have Python 3 installed:
+### 3. Install Optional Dependencies
+
+#### Wallet Dependencies
+It is not necessary to build wallet functionality to run bitcoind or the GUI. To enable legacy wallets, you must install `db5`. To enable [descriptor wallets](https://github.com/bitcoin/bitcoin/blob/master/doc/descriptors.md), `sqlite3` is required. Skip `db5` if you intend to *exclusively* use descriptor wallets
+
+###### Legacy Wallet Support
+`db5` is required to enable support for legacy wallets. Skip if you don't intend to use legacy wallets
 
 ```bash
-pkg install python3
+pkg install db5
 ```
 
-See [dependencies.md](dependencies.md) for a complete overview.
+###### Descriptor Wallet Support
 
-### Building BerkeleyDB
+`sqlite3` is required to enable support for descriptor wallets. Skip if you don't intend to use descriptor wallets.
+``` bash
+pkg install sqlite3
+```
+---
 
-BerkeleyDB is only necessary for the wallet functionality. To skip this, pass
-`--disable-wallet` to `./configure` and skip to the next section.
+#### GUI Dependencies
+###### Qt5
 
+Bitcoin Core includes a GUI built with the cross-platform Qt Framework. To compile the GUI, we need to install `qt5`. Skip if you don't intend to use the GUI.
 ```bash
-./contrib/install_db4.sh `pwd`
-export BDB_PREFIX="$PWD/db4"
+pkg install qt5
 ```
+###### libqrencode
+
+The GUI can encode addresses in a QR Code. To build in QR support for the GUI, install `libqrencode`. Skip if not using the GUI or don't want QR code functionality.
+```bash
+pkg install libqrencode
+```
+---
+
+#### Test Suite Dependencies
+There is an included test suite that is useful for testing code changes when developing.
+To run the test suite (recommended), you will need to have Python 3 installed:
+
+```bash
+pkg install python3
+```
+---
 
 ## Building Bitcoin Core
 
-**Important**: Use `gmake` (the non-GNU `make` will exit with an error).
+### 1. Configuration
 
-With wallet:
+There are many ways to configure Bitcoin Core, here are a few common examples:
+##### Wallet (BDB + SQlite) Support, No GUI:
+This explicitly enables legacy wallet support and disables the GUI. If `sqlite3` is installed, then descriptor wallet support will be built.
 ```bash
 ./autogen.sh
-./configure --with-gui=no \
-    BDB_LIBS="-L${BDB_PREFIX}/lib -ldb_cxx-4.8" \
-    BDB_CFLAGS="-I${BDB_PREFIX}/include" \
+./configure --with-gui=no --with-incompatible-bdb \
+    BDB_LIBS="-ldb_cxx-5" \
+    BDB_CFLAGS="-I/usr/local/include/db5" \
     MAKE=gmake
 ```
 
-Without wallet:
+##### Wallet (only SQlite) and GUI Support:
+This explicitly enables the GUI and disables legacy wallet support. If `qt5` is not installed, this will throw an error. If `sqlite3` is installed then descriptor wallet functionality will be built. If `sqlite3` is not installed, then wallet functionality will be disabled.
 ```bash
 ./autogen.sh
-./configure --with-gui=no --disable-wallet MAKE=gmake
+./configure --without-bdb --with-gui=yes MAKE=gmake
+```
+##### No Wallet or GUI
+``` bash
+./autogen.sh
+./configure --without-wallet --with-gui=no MAKE=gmake
 ```
 
-followed by:
+### 2. Compile
+**Important**: Use `gmake` (the non-GNU `make` will exit with an error).
 
 ```bash
 gmake # use -jX here for parallelism