Red Bear OS — microkernel OS in Rust, based on Redox

Derivative of Redox OS (https://www.redox-os.org) adding:
- AMD GPU driver (amdgpu) via LinuxKPI compat layer
- ext4 filesystem support (ext4d scheme daemon)
- ACPI fixes for AMD bare metal (x2APIC, DMAR, IVRS, MCFG)
- Custom branding (hostname, os-release, boot identity)

Build system is full upstream Redox with RBOS overlay in local/.
Patches for kernel, base, and relibc are symlinked from local/patches/
and protected from make clean/distclean. Custom recipes live in
local/recipes/ with symlinks into the recipes/ search path.

Build:  make all CONFIG_NAME=redbear-full
Sync:   ./local/scripts/sync-upstream.sh

build.sh

@@ -0,0 +1,105 @@
+#!/usr/bin/env bash
+
+# Alternative script for the build system Makefiles
+
+###########################################################################
+#                                                                         #
+# Build the system, with a specified processor type and filesystem config #
+#                                                                         #
+###########################################################################
+
+usage()
+{
+    echo "build.sh:      Invoke make for a particular architecture and configuration."
+    echo "Usage:"
+    echo "./build.sh [-X | -A | -5 | -R | -a ARCH] [-c CONFIG] [-f FILESYSTEM_CONFIG] TARGET..."
+    echo "    -X         Equivalent to -a x86_64."
+    echo "    -A         Equivalent to -a aarch64."
+    echo "    -5         Equivalent to -a i586."
+    echo "    -6         Equivalent to -a i586 (deprecated, use -5 instead)."
+    echo "    -R         Equivalent to -a riscv64gc."
+    echo "    -a ARCH:   Processor Architecture. Normally one of x86_64, aarch64 or"
+    echo "               i686. ARCH is not checked, so you can add a new architecture."
+    echo "               Defaults to the directory containing the FILESYSTEM_CONFIG file,"
+    echo "               or x86_64 if no FILESYSTEM_CONFIG is specified."
+    echo "    -c CONFIG: The name of the config, e.g. desktop, server or demo."
+    echo "               Determines the name of the image, build/ARCH/CONFIG/harddrive.img"
+    echo "               e.g. build/x86_64/desktop/harddrive.img"
+    echo "               Determines the name of FILESYSTEM_CONFIG if none is specified."
+    echo "               Defaults to the basename of FILESYSTEM_CONFIG, or 'desktop'"
+    echo "               if FILESYSTEM_CONFIG is not specified."
+    echo "    -f FILESYSTEM_CONFIG:"
+    echo "               The config file to use. It can be in any location."
+    echo "               However, if the file is not in a directory named x86_64, aarch64"
+    echo "               or i686, you must specify the architecture."
+    echo "               If -f is not specified, FILESYSTEM_CONFIG is set to"
+    echo "               config/ARCH/CONFIG.toml"
+    echo "               If you specify both CONFIG and FILESYSTEM_CONFIG, it is not"
+    echo "               necessary that they match, but it is recommended."
+    echo "    Examples:  ./build.sh -c demo live - make build/x86_64/demo/rbos-live.iso"
+    echo "               ./build.sh -6 qemu - make build/i686/desktop/harddrive.img and"
+    echo "                                    and run it in qemu"
+    echo "    NOTE:      If you do not change ARCH or CONFIG very often, edit mk/config.mk"
+    echo "               and set ARCH and FILESYSTEM_CONFIG. You only need to use this"
+    echo "               script when you want to override them."
+}
+
+if [ "$1" == "-h" ] || [ "$1" == "--help" ]; then
+    usage
+    exit
+fi
+
+defaultarch="x86_64"
+defaultname="desktop"
+ARCH=""
+CONFIG_NAME=""
+FILESYSTEM_CONFIG=""
+
+while getopts ":c:f:a:dhXA6" opt
+do
+    case "$opt" in
+        a) ARCH="$OPTARG";;
+        c) CONFIG_NAME="$OPTARG";;
+        f) FILESYSTEM_CONFIG="$OPTARG";;
+        X) ARCH="x86_64";;
+        A) ARCH="aarch64";;
+        R) ARCH="riscv64gc";;
+        5) ARCH="i586";;
+        6) ARCH="i586";;
+        h) usage;;
+        \?) echo "Unknown option -$OPTARG, try -h for help"; exit;;
+        :) echo "-$OPTARG requires a value"; exit;;
+    esac
+done
+shift $((OPTIND -1))
+
+if [ -z "$ARCH" ] && [ -n "$FILESYSTEM_CONFIG" ]; then
+    dirname=`dirname "$FILESYSTEM_CONFIG"`
+    ARCH=`basename $dirname`
+    case "$ARCH" in
+        x86_64) : ;;
+        aarch64) : ;;
+        riscv64gc) : ;;
+        i586) : ;;
+        \?) ARCH=""; echo "Unknown Architecture, please specify x86_64, aarch64, riscv64gc or i586";;
+    esac
+fi
+
+if [ -z "$config_name" ] && [ -n "$FILESYSTEM_CONFIG" ]; then
+    CONFIG_NAME=`basename "$FILESYSTEM_CONFIG" .toml`
+fi
+
+if [ -z "$ARCH" ]; then
+    ARCH="$defaultarch"
+fi
+
+if [ -z "$CONFIG_NAME" ]; then
+    CONFIG_NAME="$defaultname"
+fi
+
+if [ -z "$FILESYSTEM_CONFIG" ]; then
+    FILESYSTEM_CONFIG="config/$ARCH/$CONFIG_NAME.toml"
+fi
+
+export ARCH CONFIG_NAME FILESYSTEM_CONFIG
+make $@