docs(ci): add some build docs (#4884)

Description
Document some of the build process

Motivation and Context
For builds other than native, some info recorded to build others get a jump start.

.license.ignore

@@ -15,6 +15,7 @@
 ./base_layer/wallet/src/schema.rs
 ./base_layer/p2p/src/dns/roots/tls.rs
 ./buildtools/docker/torrc
+./buildtools/vagrant/Vagrantfile
 ./docs/src/theme/book.js
 ./docs/src/theme/highlight.js
 ./integration_tests/Makefile

buildtools/build-notes.md

@@ -0,0 +1,140 @@
+## Build Notes we don't want to lose?
+
+Build options:
+ - Native
+ - Docker
+ - Virtualised
+ - Emulated
+
+# Building Linux x86_64 & ARM64
+
+Using Vagrant and VirtualBox has a baseline for building needs, including tools, libs and testing
+
+Linux ARM64 can be built using Vagrant and VirtualBox or Docker and cross
+
+# Prep Ubuntu for development
+# From - https://github.com/tari-project/tari/blob/development/scripts/install_ubuntu_dependencies.sh
+```bash
+sudo apt-get update
+sudo apt-get install \
+  openssl \
+  libssl-dev \
+  pkg-config \
+  libsqlite3-dev \
+  clang-10 \
+  git \
+  cmake \
+  dh-autoreconf \
+  libc++-dev \
+  libc++abi-dev \
+  libprotobuf-dev \
+  protobuf-compiler \
+  libncurses5-dev \
+  libncursesw5-dev \
+  zip
+```
+
+# Prep Ubuntu for cross-compile aarch64/arm64 on x86_64
+```bash
+sudo apt-get install \
+  pkg-config-aarch64-linux-gnu \
+  gcc-aarch64-linux-gnu \
+  g++-aarch64-linux-gnu
+```
+
+# Install rust
+```bash
+curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
+```
+# or unattended rust install
+```bash
+curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y
+```
+
+```bash
+source "$HOME/.cargo/env"
+```
+
+# Prep rust for cross-compile aarch64/arm64 on x86_64
+```bash
+rustup target add aarch64-unknown-linux-gnu
+rustup toolchain install stable-aarch64-unknown-linux-gnu
+```
+
+# Check was tools chains rust has in place
+```bash
+rustup target list --installed
+rustup toolchain list
+```
+
+# get/git the code base
+```bash
+mkdir -p ~/src
+cd ~/src
+git clone [email protected]:tari-project/tari.git
+cd tari
+```
+
+# Needed for RandomX
+```bash
+export CARGO_TARGET_AARCH64_UNKNOWN_LINUX_GNU_LINKER=aarch64-linux-gnu-gcc
+export BINDGEN_EXTRA_CLANG_ARGS='--sysroot /usr/aarch64-linux-gnu/include/'
+```
+Sample of the errors seen, if the above envs are not set
+```
+Compiling randomx-rs v1.1.13 (https://github.com/tari-project/randomx-rs?tag=v1.1.13#c33f8679)
+error: linking with `cc` failed: exit status: 1
+|
+= note: "cc" "-Wl,--version-script=/tmp/rustcsAUjg7/list" "/tmp/rustcsAUjg7/symbols.o" "/home/vagrant/src/tari/target/aarch64-unknown-linux-gnu/debug/deps/randomx_rs-aa21b69d885376e9.randomx_rs.a9fc037b-cgu.0.rcgu.o"
+```
+...
+```
+/usr/bin/ld: /home/vagrant/src/tari/target/aarch64-unknown-linux-gnu/debug/deps/randomx_rs-aa21b69d885376e9.randomx_rs.a9fc037b-cgu.0.rcgu.o: Relocations in generic ELF (EM: 183)
+/home/vagrant/src/tari/target/aarch64-unknown-linux-gnu/debug/deps/randomx_rs-aa21b69d885376e9.randomx_rs.a9fc037b-cgu.0.rcgu.o: error adding symbols: File in wrong format
+collect2: error: ld returned 1 exit status
+
+error: could not compile `randomx-rs` due to previous error
+warning: build failed, waiting for other jobs to finish...
+```
+Might not need these older envs
+```
+export AR_aarch64_unknown_linux_gnu=aarch64-linux-gnu-ar
+export CC_aarch64_unknown_linux_gnu=aarch64-linux-gnu-gcc
+export CXX_aarch64_unknown_linux_gnu=aarch64-linux-gnu-g++
+```
+
+# Needed in the past for croaring-sys
+```bash
+export ARCH=generic
+export ROARING_ARCH=generic
+export RUSTFLAGS='-C target_cpu=generic'
+export CROSS_COMPILE=true
+```
+
+# Build Testing
+```bash
+cargo build \
+  --target aarch64-unknown-linux-gnu \
+  --bin tari_miner
+```
+
+# Build target Release
+```bash
+cargo build --locked \
+  --release --features safe \
+  --target aarch64-unknown-linux-gnu
+```
+
+# Using a single command line build using Docker
+```bash
+cross build --locked \
+  --release --features safe \
+  --target aarch64-unknown-linux-gnu
+```
+```bash
+cross build --locked \
+  --release --features safe \
+  --target aarch64-unknown-linux-gnu \
+  --bin tari_base_node --bin tari_console_wallet \
+  --bin tari_merge_mining_proxy --bin tari_miner
+```

buildtools/vagrant/.gitignore

@@ -0,0 +1,2 @@
+.vagrant
+*.log

buildtools/vagrant/Vagrantfile

@@ -0,0 +1,41 @@
+# -*- mode: ruby -*-
+# vi: set ft=ruby :
+
+Vagrant.configure("2") do |config|
+  config.vm.box = "ubuntu/bionic64"
+
+  # Disable automatic box update checking. If you disable this, then
+  # boxes will only be checked for updates when the user runs
+  # `vagrant box outdated`. This is not recommended.
+  # config.vm.box_check_update = false
+  config.vm.box_check_update = false
+
+  # https://subscription.packtpub.com/book/virtualization_and_cloud/9781786464910/1/ch01lvl1sec12/enabling-virtualbox-guest-additions-in-vagrant
+  # vagrant vbguest --status
+  # vagrant vbguest --do install
+  if Vagrant.has_plugin?("vagrant-vbguest") then
+    config.vbguest.auto_update = false
+  end
+
+  # Share an additional folder to the guest VM. The first argument is
+  # the path on the host to the actual folder. The second argument is
+  # the path on the guest to mount the folder. And the optional third
+  # argument is a set of non-required options.
+  # config.vm.synced_folder "../data", "/vagrant_data"
+
+  # virtualbox settings
+  config.vm.provider :virtualbox do |vb|
+    vb.cpus = 2
+    vb.memory = 5*1024
+    vb.gui = false
+    vb.linked_clone = true
+  end
+
+  # Enable provisioning with a shell script. Additional provisioners such as
+  # Ansible, Chef, Docker, Puppet and Salt are also available. Please see the
+  # documentation for more information about their specific syntax and use.
+  # config.vm.provision "shell", inline: <<-SHELL
+  #   apt-get update
+  #   apt-get install -y apache2
+  # SHELL
+end

scripts/install_ubuntu_dependencies-arm64.sh

@@ -0,0 +1,8 @@
+#!/usr/bin/env sh
+#
+# Install Ubuntu aarch64/arm64 deb dev/tool packages on x86_64
+#
+apt-get -y install $* \
+  pkg-config-aarch64-linux-gnu \
+  gcc-aarch64-linux-gnu \
+  g++-aarch64-linux-gnu

scripts/install_ubuntu_dependencies-rust-arm64.sh

@@ -0,0 +1,7 @@
+#!/usr/bin/env sh
+#
+# Install rust target/toolchain for aarch64/arm64
+#
+export PATH="$HOME/.cargo/bin:$PATH"
+rustup target add aarch64-unknown-linux-gnu
+rustup toolchain install stable-aarch64-unknown-linux-gnu

scripts/install_ubuntu_dependencies-rust.sh

@@ -0,0 +1,6 @@
+#!/usr/bin/env sh
+#
+# Install rust unattended - https://www.rust-lang.org/tools/install
+#
+curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y
+export PATH="$HOME/.cargo/bin:$PATH"