scripts: Add a script for building and booting QEMU

It is handy to be able to quickly build and boot a QEMU image for a
particular architecture and distro.

Add a script for this purpose. It supports only arm and x86 at present.
For distros it only supports Ubuntu. Both 32- and 64-bit builds are
supported.

Signed-off-by: Simon Glass <sjg@chromium.org>

MAINTAINERS

@@ -1111,6 +1111,14 @@ F:	tools/efivar.py
 F:	tools/file2include.c
 F:	tools/mkeficapsule.c
 
+EMULATION
+M:	Simon Glass <sjg@chromium.org>
+S:	Maintained
+W:	https://docs.u-boot.org/en/latest/board/emulation/script.html
+F:	configs/qemu_x86*
+F:	doc/board/emulation/script.rst
+F:	scripts/build-qemu.sh
+
 ENVIRONMENT
 M:	Joe Hershberger <joe.hershberger@ni.com>
 S:	Maintained

doc/board/emulation/index.rst

@@ -8,6 +8,7 @@ Emulation
 
    acpi
    blkdev
+   script
    qemu-arm
    qemu-mips
    qemu-ppce500

doc/board/emulation/script.rst

@@ -0,0 +1,61 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+Script for building and running
+===============================
+
+You may find the script `scripts/build-qemu.sh` helpful for building and testing
+U-Boot on QEMU.
+
+If uses a environment variables to control how it works:
+
+ubdir
+    base directory for building U-Boot, with each board being in its own
+    subdirectory
+
+imagedir
+    directory containing OS images, containin a subdirectory for each distro
+    type (e.g. ubuntu/
+
+Once configured, you can build and run QEMU for arm64 like this::
+
+    scripts/build-qemu.sh -rsw
+
+No support is currently included for specifying a root disk, so this script can
+only be used to start installers.
+
+Options
+~~~~~~~
+
+Options are available to control the script:
+
+-a <arch>
+    Select architecture (default arm, x86)
+
+-B
+    Don't build; assume a build exists
+
+-k
+    Use kvm - kernel-based Virtual Machine. By default QEMU uses its own
+    emulator
+
+-o <os>
+    Run an Operating System. For now this only supports 'ubuntu'. The name of
+    the OS file must remain unchanged from its standard name on the Ubuntu
+    website.
+
+-r
+    Run QEMU with the image (by default this is not done)
+
+-R
+    Select OS release (e.g. 24.04).
+
+-s
+    Use serial only (no display)
+
+-w
+    Use word version (32-bit). By default, 64-bit is used
+
+.. note::
+
+    Note: For now this is a shell script, but if it expands it might be better
+    as Python, accepting the slower startup.

scripts/build-qemu.sh

@@ -0,0 +1,175 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Script to build U-Boot suitable for booting with QEMU, possibly running
+# it, possibly with an OS image
+
+# This just an example. It assumes that
+
+# - you build U-Boot in ${ubdir}/<name> where <name> is the U-Boot board config
+# - your OS images are in ${imagedir}/{distroname}/...
+
+# So far the script supports only ARM and x86.
+
+set -e
+
+usage() {
+	(
+	if [[ -n "$1" ]]; then
+		echo "$1"
+		echo
+	fi
+	echo "Usage: $0 -aBkrsw"
+	echo
+	echo "   -a   - Select architecture (arm, x86)"
+	echo "   -B   - Don't build; assume a build exists"
+	echo "   -k   - Use kvm (kernel-based Virtual Machine)"
+	echo "   -o   - Run Operating System ('ubuntu' only for now)"
+	echo "   -r   - Run QEMU with the image"
+	echo "   -R   - Select OS release (e.g. 24.04)"
+	echo "   -s   - Use serial only (no display)"
+	echo "   -w   - Use word version (32-bit)" ) >&2
+	exit 1
+}
+
+# Directory tree for OS images
+imagedir=${imagedir-/vid/software/linux}
+
+# architecture (arm or x86)
+arch=arm
+
+# 32- or 64-bit build
+bitness=64
+
+# Build U-Boot
+build=yes
+
+# Extra setings
+extra=
+
+# Operating System to boot (ubuntu)
+os=
+
+release=24.04.1
+
+# run the image with QEMU
+run=
+
+# run QEMU without a display (U-Boot must be set to stdout=serial)
+serial=
+
+# Use kvm
+kvm=
+
+# Set ubdir to the build directory where you build U-Boot out-of-tree
+# We avoid in-tree build because it gets confusing trying different builds
+ubdir=${ubdir-/tmp/b}
+
+while getopts "a:Bko:rR:sw" opt; do
+	case "${opt}" in
+	a)
+		arch=$OPTARG
+		;;
+	B)
+		build=
+		;;
+	k)
+		kvm="-enable-kvm"
+		;;
+	o)
+		os=$OPTARG
+
+		# Expand memory and CPUs
+		extra+=" -m 4G -smp 4"
+		;;
+	r)
+		run=1
+		;;
+	R)
+		release=$OPTARG
+		;;
+	s)
+		serial=1
+		;;
+	w)
+		bitness=32
+		;;
+	*)
+		usage
+		;;
+	esac
+done
+
+# Build U-Boot for the selected board
+build_u_boot() {
+	buildman -w -o $DIR --board $BOARD -I || exit $?
+}
+
+# Run QEMU with U-Boot
+run_qemu() {
+	if [[ -n "${os_image}" ]]; then
+		extra+=" -drive if=virtio,file=${os_image},format=raw,id=hd0"
+	fi
+	if [[ -n "${serial}" ]]; then
+		extra+=" -display none -serial mon:stdio"
+	else
+		extra+=" -serial mon:stdio"
+	fi
+	echo "Running ${qemu} ${extra}"
+	"${qemu}" -bios "$DIR/${BIOS}" \
+		-m 512 \
+		-nic none \
+		${kvm} \
+		${extra}
+}
+
+# Check architecture
+case "${arch}" in
+arm)
+	BOARD="qemu_arm"
+	BIOS="u-boot.bin"
+	qemu=qemu-system-arm
+	extra+=" -machine virt"
+	suffix="arm"
+	if [[ "${bitness}" == "64" ]]; then
+		BOARD="qemu_arm64"
+		qemu=qemu-system-aarch64
+		extra+=" -cpu cortex-a57"
+		suffix="arm64"
+	fi
+	;;
+x86)
+	BOARD="qemu-x86"
+	BIOS="u-boot.rom"
+	qemu=qemu-system-i386
+	suffix="i386"
+	if [[ "${bitness}" == "64" ]]; then
+		BOARD="qemu-x86_64"
+		qemu=qemu-system-x86_64
+		suffix="amd64"
+	fi
+	;;
+*)
+	usage "Unknown architecture '${arch}'"
+esac
+
+# Check OS
+case "${os}" in
+ubuntu)
+	os_image="${imagedir}/${os}/${os}-${release}-desktop-${suffix}.iso"
+	;;
+"")
+	;;
+*)
+	usage "Unknown OS '${os}'"
+esac
+
+DIR=${ubdir}/${BOARD}
+
+if [[ -n "${build}" ]]; then
+	build_u_boot
+fi
+
+if [[ -n "${run}" ]]; then
+	run_qemu
+fi