Toolchain: Add QEMU build script and improve documentation

Added a script to build QEMU from source as part of the Toolchain.
The script content could be in BuildIt.sh but has been put in
a seperate file to make the build optional.

Added PATH=$PATH to sudo calls to hand over the Toolchain's PATH
setup by UseIt.sh. This enabled the script's to use the QEMU
contained in the SerenityOS toolchain.

Deleted old documentation in Meta and replaced it by a new
documentation in the Toolchain folder.

3 files changed, 213 insertions, 0 deletions

diff --git a/Toolchain/.gitignore b/Toolchain/.gitignore
new file mode 100644
index 0000000000..0146895ec6
--- /dev/null
+++ b/Toolchain/.gitignore
@@ -0,0 +1,3 @@
+# Created by QEMU build
+config-temp
+config.log
diff --git a/Toolchain/BuildQemu.sh b/Toolchain/BuildQemu.sh
new file mode 100755
index 0000000000..d43dea9ec7
--- /dev/null
+++ b/Toolchain/BuildQemu.sh
@@ -0,0 +1,66 @@
+#!/bin/bash
+set -e
+
+# This file will need to be run in bash, for now.
+
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+
+echo "$DIR"
+
+TARGET=i686-pc-serenity
+PREFIX="$DIR/Local"
+SYSROOT="$DIR/../Root"
+
+QEMU300_MD5SUM="6a5c8df583406ea24ef25b239c3243e0"
+QEMU410_MD5SUM="cdf2b5ca52b9abac9bacb5842fa420f8"
+
+QEMU_VERSION="qemu-4.1.0"
+QEMU_MD5SUM="${QEMU410_MD5SUM}"
+
+echo PREFIX is "$PREFIX"
+echo SYSROOT is "$SYSROOT"
+
+mkdir -p "$DIR/Tarballs"
+
+source "$DIR/UseIt.sh"
+
+pushd "$DIR/Tarballs"
+
+    md5="$(md5sum $QEMU_VERSION.tar.xz | cut -f1 -d' ')"
+    echo "qemu md5='$md5'"
+    if [ ! -e "$QEMU_VERSION.tar.xz" ] || [ "$md5" != "$QEMU_MD5SUM" ] ; then
+        rm -f qemu-3.0.0.tar.xz
+        curl -O "https://download.qemu.org/$QEMU_VERSION.tar.xz"
+
+        if  [ "$md5" != "$QEMU_MD5SUM" ] ; then
+            echo "qemu md5 sum mismatching, please run script again."
+            exit 1
+        fi
+    else
+        echo "Skipped downloading $QEMU_VERSION"
+    fi
+
+    if [ ! -d "$QEMU_VERSION" ]; then
+        echo "Extracting qemu..."
+        tar -xf "$QEMU_VERSION.tar.xz"
+    else
+        echo "Skipped extracting qemu"
+    fi
+popd
+
+mkdir -p "$PREFIX"
+mkdir -p "$DIR/Build/qemu"
+
+if [ -z "$MAKEJOBS" ]; then
+    MAKEJOBS=$(nproc)
+fi
+
+pushd "$DIR/Build/"
+    pushd qemu
+        "$DIR"/Tarballs/$QEMU_VERSION/configure --prefix="$PREFIX" \
+                                                --target-list=i386-softmmu \
+                                                --enable-gtk || exit 1
+        make -j "$MAKEJOBS" || exit 1
+        make install || exit 1
+    popd
+popd
diff --git a/Toolchain/README.md b/Toolchain/README.md
new file mode 100644
index 0000000000..92dafa5374
--- /dev/null
+++ b/Toolchain/README.md
@@ -0,0 +1,144 @@
+# Serenity Toolchain - Building the Serenity operating system
+
+This directory contains all toolchain related files. E.g. build scripts for
+the cross compilation toolchain and build toolchain for ports.
+
+- [Serenity Toolchain - Building the Serenity operating system](#serenity-toolchain---building-the-serenity-operating-system)
+  - [Cross Compile Toolchain](#cross-compile-toolchain)
+    - [Dependencies](#dependencies)
+  - [Serenity (Full build)](#serenity-full-build)
+  - [Running SerenityOS in an emulator](#running-serenityos-in-an-emulator)
+    - [QEMU installation / compilation](#qemu-installation--compilation)
+    - [Passing custom arguments to QEMU](#passing-custom-arguments-to-qemu)
+
+## Cross Compile Toolchain
+
+The cross compile toolchain contains
+
+- binutils 2.32
+
+- GCC 8.3.0
+
+These are built from source with some patches applied.
+
+### Dependencies
+
+- Build Essentials
+
+    ```bash
+    sudo apt install build-essential curl libmpfr-dev libmpc-dev libgmp-dev
+    ```
+
+- GCC 8
+
+    ```bash
+    sudo add-apt-repository ppa:ubuntu-toolchain-r/test
+    sudo apt-get install gcc-8 g++-8
+    sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-8 800 --slave /usr/bin/g++ g++ /usr/bin/g++-8
+    ```
+
+- e2fsprogs
+
+    ```bash
+    sudo apt install e2fsprogs
+    ```
+
+## Serenity (Full build)
+
+If everything worked out, you now have the **i686-pc-serenity** toolchain ready and we can build Serenity.
+
+Go into `Kernel/` folder and build it:
+
+```bash
+./makeall.sh
+```
+
+Then take it for a spin:
+
+```bash
+./run
+```
+
+See next chapter for more options on running SerenityOS in an emulator.
+
+## Running SerenityOS in an emulator
+
+To run SerenityOS in a specific emulator, call the `./run` command in the `Kernel/` folder:
+
+```bash
+./run
+```
+
+There are several emulators supported to run SerenityOS in:
+
+- Bochs
+
+    ```bash
+    sudo apt install bochs
+    ```
+
+    Add the `b` argument to the run script, to use bochs emulator:
+
+    ```bash
+    ./run b
+    ```
+
+- QEMU
+    QEMU with networking enabled is used by default, when no extra argument is passed to the run script.
+    There are some extra arguments to run QEMU emulator with specific settings:
+
+    Add the `qn` argument to the run script to use QEMU without networking:
+
+    ```bash
+    ./run qn
+    ```
+
+    Add the `qgrub` argument to the run script to use QEMU with grub bootloader:
+
+    ```bash
+    ./run qgrub
+    ```
+
+    Add the `qtext` argument to the run script to use QEMU with textmode:
+
+    ```bash
+    ./run qtext
+    ```
+
+    Note: there is a problem with the PS/2 keyboard/mouse emulation in QEMU 2.11.1 as packaged in Ubuntu's LTS releases.
+    If you have any strange behaviour with missing keyboard inputs or jittery mouse movement, try building QEMU from
+    source as described in [QEMU](#qemu-installation--compilation). 2.12.1, 3.0.1, 3.1.0, and 4.0.0 are all confirmed as working when built from source.
+
+### QEMU installation / compilation
+
+If your distribution contains a QEMU version > 2.11.1, then you can just install it via
+
+```bash
+sudo apt install qemu-system-i386 qemu-utils
+```
+
+If that is not the case, you can build QEMU from sources with the provided script `BuildQemu.sh`.
+To do so, some build dependencies have to be installed first:
+
+```bash
+sudo apt-get build-dep qemu
+sudo apt-get install libgtk-3-dev
+```
+
+The source-repositories of your distribution have to be enabled to install the build-dep's.
+
+`BuildQemu.sh` has been tested with QEMU 3.0.0 and 4.1.0 (which is default). If you
+want to build QEMU 3.0.0, change the variable `QEMU_VERSION` and `QEMU_MD5SUM` accordingly:
+
+```bash
+QEMU_VERSION="qemu-3.0.0"
+QEMU_MD5SUM="${QEMU300_MD5SUM}"
+```
+
+### Passing custom arguments to QEMU
+
+You can modify the environment variable `SERENITY_EXTRA_QEMU_ARGS` to your needs or hand it over directly before the run command:
+
+```bash
+SERENITY_EXTRA_QEMU_ARGS="-nographic" ./run qtext
+```