docker-qemu/start-qemu
Tianon Gravi 8e51bdb10d Try writing zero bytes to "/dev/kvm" as a more robust test for access
Looking at https://lwn.net/Articles/658511/, this seems like it should be reasonably harmless as a simple test of whether we can expect `/dev/kvm` to work.

Fixes #4
2021-03-19 08:57:33 -07:00

110 lines
2.6 KiB
Bash
Executable File

#!/bin/bash
set -e
# main available options:
# QEMU_CPU=n (cores)
# QEMU_RAM=nnn (megabytes)
# QEMU_HDA (filename)
# QEMU_HDA_SIZE (bytes, suffixes like "G" allowed)
# QEMU_CDROM (filename)
# QEMU_BOOT (-boot)
# QEMU_PORTS="xxx[ xxx ...]" (space separated port numbers)
# QEMU_NET_USER_EXTRA="net=192.168.76.0/24,dhcpstart=192.168.76.9" (extra raw args for "-net user,...")
# QEMU_NO_SSH=1 (suppress automatic port 22 forwarding)
# QEMU_NO_SERIAL=1 (suppress automatic "-serial stdio")
# QEMU_NO_VNC=1 (suppress automatic "-vnc ':0'")
hostArch="$(uname -m)"
qemuArch="${QEMU_ARCH:-$hostArch}"
qemu="${QEMU_BIN:-qemu-system-$qemuArch}"
qemuArgs=()
qemuPorts=()
if [ -z "${QEMU_NO_SSH:-}" ]; then
qemuPorts+=( 22 )
fi
qemuPorts+=( ${QEMU_PORTS:-} )
if [ -e /dev/kvm ] && sh -c 'echo -n > /dev/kvm' &> /dev/null; then
# https://github.com/tianon/docker-qemu/issues/4
qemuArgs+=( -enable-kvm )
elif [ "$hostArch" = "$qemuArch" ]; then
echo >&2
echo >&2 'warning: /dev/kvm not found'
echo >&2 ' PERFORMANCE WILL SUFFER'
echo >&2 ' (hint: docker run --device /dev/kvm ...)'
echo >&2
sleep 3
fi
qemuArgs+=( -smp "${QEMU_CPU:-1}" )
qemuArgs+=( -m "${QEMU_RAM:-512}" )
if [ -n "${QEMU_HDA:-}" ]; then
if [ ! -f "$QEMU_HDA" -o ! -s "$QEMU_HDA" ]; then
(
set -x
qemu-img create -f qcow2 -o preallocation=off "$QEMU_HDA" "${QEMU_HDA_SIZE:-8G}"
)
fi
# http://wiki.qemu.org/download/qemu-doc.html#Invocation
qemuScsiDevice='virtio-scsi-pci'
case "$qemuArch" in
arm | riscv64) qemuScsiDevice='virtio-scsi-device' ;;
esac
#qemuArgs+=( -hda "$QEMU_HDA" )
#qemuArgs+=( -drive file="$QEMU_HDA",index=0,media=disk,discard=unmap )
qemuArgs+=(
-drive file="$QEMU_HDA",index=0,media=disk,discard=unmap,detect-zeroes=unmap,if=none,id=hda
-device "$qemuScsiDevice"
-device scsi-hd,drive=hda
)
fi
if [ -n "${QEMU_CDROM:-}" ]; then
qemuArgs+=( -cdrom "$QEMU_CDROM" )
fi
if [ -n "${QEMU_BOOT:-}" ]; then
qemuArgs+=( -boot "$QEMU_BOOT" )
fi
netArg='user'
netArg+=",hostname=$(hostname)"
if [ -n "${QEMU_NET_USER_EXTRA:-}" ]; then
netArg+=",$QEMU_NET_USER_EXTRA"
fi
for port in "${qemuPorts[@]}"; do
netArg+=",hostfwd=tcp::$port-:$port"
netArg+=",hostfwd=udp::$port-:$port"
done
qemuNetDevice='virtio-net-pci'
case "$qemuArch" in
arm | riscv64) qemuNetDevice='virtio-net-device' ;;
esac
qemuArgs+=(
-netdev "$netArg,id=net"
-device "$qemuNetDevice,netdev=net"
)
if [ -z "${QEMU_NO_SERIAL:-}" ]; then
qemuArgs+=(
-serial stdio
)
fi
if [ -z "${QEMU_NO_VNC:-}" ]; then
qemuArgs+=(
-vnc ':0'
)
fi
qemuArgs+=( "$@" )
set -x
exec "$qemu" "${qemuArgs[@]}"