Add support for User Mode Linux

boot-qemu.sh

@@ -3,29 +3,7 @@
 # Root of the repo
 BASE=$(cd "$(dirname "$(readlink -f "${BASH_SOURCE[0]}")")" && pwd)
 
-function pretty_print() {
-    printf "%b%s\033[0m" "${1}" "${2}"
-    shift 2
-    while ((${#})); do
-        printf "%b" "${1}"
-        shift
-    done
-    printf '\n'
-}
-
-function green() {
-    pretty_print "\033[01;32m" "${@}"
-}
-
-function red() {
-    pretty_print "\033[01;31m" "${@}"
-}
-
-# Prints an error message in bold red then exits
-function die() {
-    red "${@}"
-    exit 1
-}
+source "${BASE}"/utils.sh
 
 # Check that a binary is found
 function checkbin() {
@@ -155,21 +133,6 @@ function get_default_smp_value() {
     fi
 }
 
-# Expands '-k' to an absolute path to a kernel image if necessary
-function get_full_kernel_path() {
-    # If '-k' is an path that ends in the kernel image, we can just use it directly
-    if [[ ${KERNEL_LOCATION##*/} = "${KIMAGE:=zImage}" ]]; then
-        KERNEL=${KERNEL_LOCATION}
-    # If not though, we need to find it based on the kernel build directory
-    else
-        # If the image is an uncompressed vmlinux, it is in the root of the build folder
-        # Otherwise, it is in the architecture's boot directory
-        [[ ${KIMAGE} == "vmlinux" ]] || BOOT_DIR=arch/${ARCH}/boot/
-        KERNEL=${KERNEL_LOCATION}/${BOOT_DIR}${KIMAGE}
-    fi
-    [[ -f ${KERNEL} ]] || die "${KERNEL} does not exist!"
-}
-
 # Takes a version (x.y.z) and prints a six or seven digit number
 # For example, QEMU 6.2.50 would become 602050 and Linux 5.10.100
 # would become 510100

boot-uml.sh

@@ -0,0 +1,42 @@
+#!/usr/bin/env bash
+
+BASE=$(dirname "$(readlink -f "$0")")
+source "$BASE"/utils.sh
+
+function parse_parameters() {
+    while (($#)); do
+        case $1 in
+            -i | --interactive | --shell)
+                kernel_args=(init=/bin/sh)
+                ;;
+            -k | --kernel-location)
+                shift
+                KERNEL_LOCATION=$1
+                ;;
+        esac
+        shift
+    done
+}
+
+function reality_check() {
+    [[ -z $KERNEL_LOCATION ]] && die "Kernel image or kernel build folder ('-k') is required but not specified!"
+    KIMAGE=linux get_full_kernel_path
+}
+
+function decomp_rootfs() {
+    rootfs=$BASE/images/x86_64/rootfs.ext4
+    rm -rf "$rootfs"
+    zstd -q -d "$rootfs".zst -o "$rootfs"
+}
+
+function execute_kernel() {
+    # exec is needed to avoid a "Killed" message when the kernel shuts down:
+    # https://github.com/ClangBuiltLinux/boot-utils/issues/60
+    # Nothing runs after this command so it is okay for it to replace this process.
+    exec "$KERNEL" ubd0="$rootfs" "${kernel_args[@]}"
+}
+
+parse_parameters "$@"
+reality_check
+decomp_rootfs
+execute_kernel

buildroot/buildroot-2022.02.tar.gz.sha256

@@ -0,0 +1 @@
+9aaaa1317ca1082ccdabe3f2566bba06975080a80256adf87f860bc4c3f45a9b  buildroot-2022.02.tar.gz

buildroot/rebuild.sh

@@ -39,7 +39,7 @@ while ((${#})); do
 done
 
 # Download latest LTS buildroot release
-BUILDROOT_VERSION=2020.11.2
+BUILDROOT_VERSION=2022.02
 if [[ -d src ]]; then
     # Make support/scripts/setlocalversion do nothing because we are in a git
     # repository so it will return information about this repo, not Buildroot
@@ -53,9 +53,6 @@ if [[ -d src ]]; then
 else
     download_br
 fi
-# Patch buildroot with fakeroot fixes for newer glibc versions
-[[ ! -f src/package/fakeroot/0002-libfakeroot.c-define-_STAT_VER-if-not-already-define.patch ]] &&
-    curl -LSs https://github.com/buildroot/buildroot/commit/f45925a951318e9e53bead80b363e004301adc6f.patch | patch -d src -p1
 cd src || exit 1
 
 # Build the images for the architectures requested
@@ -84,6 +81,8 @@ for CONFIG in "${CONFIGS[@]}"; do
     # Copy new images
     # Make sure images exist before moving them
     IMAGES=("output/images/rootfs.cpio")
+    # For x86_64, we also build an ext4 image for UML
+    [[ ${ARCH} == "x86_64" ]] && IMAGES+=("output/images/rootfs.ext4")
     for IMAGE in "${IMAGES[@]}"; do
         [[ -f ${IMAGE} ]] || die "${IMAGE} could not be found! Did the build error?"
         zstd -f -19 "${IMAGE}" -o "${IMAGES_FOLDER}/${IMAGE##*/}.zst" || die "Compressing ${IMAGE##*/} failed!"

buildroot/riscv.config

@@ -1,6 +1,6 @@
 BR2_riscv=y
-BR2_RISCV_ABI_LP64=y
 BR2_TOOLCHAIN_EXTERNAL=y
+BR2_TOOLCHAIN_EXTERNAL_BOOTLIN_RISCV64_LP64D_GLIBC_STABLE=y
 BR2_TARGET_GENERIC_ROOT_PASSWD="root"
 BR2_TARGET_GENERIC_GETTY_PORT="ttyS0"
 BR2_ROOTFS_OVERLAY="../overlay-poweroff"

buildroot/x86_64.config

@@ -6,4 +6,7 @@ BR2_TARGET_GENERIC_ROOT_PASSWD="root"
 BR2_TARGET_GENERIC_GETTY_PORT="ttyS0"
 BR2_ROOTFS_OVERLAY="../overlay-poweroff"
 BR2_TARGET_ROOTFS_CPIO=y
+BR2_TARGET_ROOTFS_EXT2=y
+BR2_TARGET_ROOTFS_EXT2_4=y
+BR2_TARGET_ROOTFS_EXT2_SIZE="10M"
 # BR2_TARGET_ROOTFS_TAR is not set

images/.gitignore

@@ -1,2 +1,3 @@
 debian.img
 rootfs.cpio
+rootfs.ext4

utils.sh

@@ -0,0 +1,42 @@
+#!/usr/bin/env bash
+
+function pretty_print() {
+    printf "%b%s\033[0m" "${1}" "${2}"
+    shift 2
+    while ((${#})); do
+        printf "%b" "${1}"
+        shift
+    done
+    printf '\n'
+}
+
+function green() {
+    pretty_print "\033[01;32m" "${@}"
+}
+
+function red() {
+    pretty_print "\033[01;31m" "${@}"
+}
+
+# Prints an error message in bold red then exits
+function die() {
+    red "${@}"
+    exit 1
+}
+
+# Expands '-k' to an absolute path to a kernel image if necessary
+function get_full_kernel_path() {
+    # If '-k' is a file, we can just use it directly
+    if [[ -f ${KERNEL_LOCATION} ]]; then
+        KERNEL=${KERNEL_LOCATION}
+    # If not, we need to find it based on the kernel build directory
+    else
+        # If the image is an uncompressed vmlinux or a UML image, it is in the
+        # root of the build folder
+        # Otherwise, it is in the architecture's boot directory
+        [[ -z ${KIMAGE} ]] && KIMAGE=zImage
+        [[ ${KIMAGE} == "vmlinux" || ${KIMAGE} == "linux" ]] || BOOT_DIR=arch/${ARCH}/boot/
+        KERNEL=${KERNEL_LOCATION}/${BOOT_DIR}${KIMAGE}
+    fi
+    [[ -f ${KERNEL} ]] || die "${KERNEL} does not exist!"
+}