1 files changed, 124 insertions, 0 deletions
diff --git a/debvm-run b/debvm-run
new file mode 100755
index 0000000..112bd40
--- /dev/null
+++ b/debvm-run
@@ -0,0 +1,124 @@
+#!/bin/sh
+# Copyright 2022 Helmut Grohne <helmut@subdivi.de>
+# SPDX-License-Identifier: MIT
+
+set -u
+
+IMAGE=rootfs.ext2
+SSHPORT=
+GRAPHICAL=
+
+die() {
+	echo "$*" 1>&2
+	exit 1
+}
+
+usage() {
+	die "usage: $0 [-g] [-i image] [-s sshport] [-- qemu options]"
+}
+
+while test "$#" -gt 0; do
+	case "$1" in
+		-g)
+			GRAPHICAL=1
+			shift
+		;;
+		-i)
+			test "$#" -eq 1 && usage
+			IMAGE=$2
+			shift 2
+		;;
+		-s)
+			test "$#" -eq 1 && usage
+			SSHPORT=$2
+			shift 2
+		;;
+		--)
+			shift
+			break
+		;;
+		*)
+			usage
+		;;
+	esac
+done
+
+test -f "$IMAGE" || die "image '$IMAGE' not found"
+
+KERNELNAME=$(/sbin/debugfs "$IMAGE" -R "stat vmlinuz" | sed 's/Fast link dest: "\(.*\)"/\1/;t;d')
+INITRDNAME=$(/sbin/debugfs "$IMAGE" -R "stat initrd.img" | sed 's/Fast link dest: "\(.*\)"/\1/;t;d')
+
+cleanup() {
+	set +x
+	test -n "$KERNELTMP" && rm -f "$KERNELTMP"
+	test -n "$INITRDTMP" && rm -f "$INITRDTMP"
+}
+
+trap cleanup EXIT INT TERM QUIT
+
+KERNELTMP=$(mktemp)
+INITRDTMP=$(mktemp)
+
+ARCHITECTURE=$(dpkg --print-architecture)
+VMARCH=$ARCHITECTURE
+if command -v elf-arch >/dev/null 2>&1; then
+	/sbin/debugfs "$IMAGE" -R "cat /bin/true" > "$KERNELTMP"
+	VMARCH=$(elf-arch "$KERNELTMP")
+fi
+case "$VMARCH" in
+	arm64|s390x)
+		DISKDEV=vda
+	;;
+	*)
+		DISKDEV=sda
+	;;
+esac
+
+KERNEL_CMDLINE=root=/dev/$DISKDEV
+NETDEV="user,id=net0"
+
+set -- \
+	-m 1G \
+	-smp "$(nproc)" \
+	-kernel "$KERNELTMP" \
+	-initrd "$INITRDTMP" \
+	-drive "media=disk,format=raw,discard=unmap,file=$IMAGE" \
+	-device "virtio-net-pci,netdev=net0" \
+	"$@"
+
+if test "$ARCHITECTURE" = "$VMARCH"; then
+	QEMU=kvm
+	set -- -enable-kvm -cpu host "$@"
+else
+	case "$VMARCH" in
+		arm64)
+			QEMU=qemu-system-aarch64
+			set -- -machine virt -cpu max "$@"
+		;;
+		*)
+			QEMU="qemu-system-$VMARCH"
+		;;
+	esac
+fi
+if test "$VMARCH" = arm64; then
+	set -- -nographic "$@"
+elif test "$VMARCH" = s390x; then
+	set -- -M s390-ccw-virtio -nographic "$@"
+elif test -z "$GRAPHICAL"; then
+	KERNEL_CMDLINE="$KERNEL_CMDLINE console=ttyS0"
+	set -- -nographic "$@"
+fi
+if test -n "$SSHPORT"; then
+	NETDEV="$NETDEV,hostfwd=tcp:127.0.0.1:$SSHPORT-:22"
+fi
+set -- \
+	-append "$KERNEL_CMDLINE" \
+	-netdev "$NETDEV" \
+	"$@"
+
+set -ex
+
+/sbin/debugfs "$IMAGE" -R "cat $KERNELNAME" > "$KERNELTMP"
+/sbin/debugfs "$IMAGE" -R "cat $INITRDNAME" > "$INITRDTMP"
+
+"$QEMU" "$@"