KVM VM script to use kernel_irqchip option

#!/bin/bash

CONSOLE=mon:stdio
SMP=4
MEMSIZE=$((14 * 1024))
KERNEL=Image
INCOMING=""
FS=linaro-trusty.img
CMDLINE=""
DUMPDTB=""
DTB=""
IRQ=""

usage() {
    U=""
    if [[ -n "$1" ]]; then
        U="${U}$1\n\n"
    fi
    U="${U}Usage: $0 [options]\n\n"
    U="${U}Options:\n"
    U="$U    -c | --CPU <nr>:       Number of cores (default ${SMP})\n"
    U="$U    -m | --mem <MB>:       Memory size (default ${MEMSIZE})\n"
    U="$U    -k | --kernel <Image>: Use kernel image (default ${KERNEL})\n"
    U="$U    -s | --serial <file>:  Output console to <file>\n"
    U="$U    -i | --image <image>:  Use <image> as block device (default $FS)\n"
    U="$U    -a | --append <snip>:  Add <snip> to the kernel cmdline\n"
    U="$U    --dumpdtb <file>       Dump the generated DTB to <file>\n"
    U="$U    --dtb <file>           Use the supplied DTB instead of the auto-generated one\n"
    U="$U    --irq on/off           Turn on/off hardware support for VGIC\n"
    U="$U    -h | --help:           Show this output\n"
    U="${U}\n"
    echo -e "$U" >&2
}

while :
do
    case "$1" in
      -c | --cpu)
        SMP="$2"
        shift 2
        ;;
      -m | --mem)
        MEMSIZE="$2"
        shift 2
        ;;
      -k | --kernel)
        KERNEL="$2"
        shift 2
        ;;
      -s | --serial)
        CONSOLE="file:$2"
        shift 2
        ;;
      -i | --image)
        FS="$2"
        shift 2
        ;;
      -a | --append)
        CMDLINE="$2"
        shift 2
        ;;
      --irq)
        IRQ=",kernel_irqchip=$2"
        shift 2
        ;;
      --dumpdtb)
        DUMPDTB=",dumpdtb=$2"
        shift 2
        ;;
      --dtb)
        DTB="-dtb $2"
        shift 2
        ;;
      -h | --help)
        usage ""
        exit 1
        ;;
      --) # End of all options
        shift
        break
        ;;
      -*) # Unknown option
        echo "Error: Unknown option: $1" >&2
        exit 1
        ;;
      *)
        break
        ;;
    esac
done

BRIDGE_IF=""
ifconfig | grep -q br0
err=$?

tap=/dev/tap$(< /sys/class/net/kvmtap0/ifindex) 2>/dev/null

if [[ $err == 0 ]]; then
    echo "Using bridged networking"
        BRIDGE_IF="-netdev tap,id=net1,helper=/srv/vm/qemu/qemu-bridge-helper,vhost=on"
        #BRIDGE_IF="$BRIDGE_IF -device virtio-net-pci,netdev=net1,mac=de:ad:be:ef:f6:cd"
        BRIDGE_IF="$BRIDGE_IF -device virtio-net-pci,netdev=net1"
elif [[ "$tap" != "/dev/tap" ]]; then
    echo "Using macvtap networking"
    macaddr=$(< /sys/class/net/kvmtap0/address) 2>/dev/null
        BRIDGE_IF="-netdev tap,id=net1,vhost=on,fd=3"
        BRIDGE_IF="$BRIDGE_IF -device virtio-net-pci,netdev=net1,mac=$macaddr"
    exec 3<>$tap
fi

./qemu-system-aarch64 \
        -smp $SMP -m $MEMSIZE -machine virt${DUMPDTB}${IRQ} -cpu host \
        -kernel ${KERNEL} -enable-kvm ${DTB} \
        -drive if=none,file=$FS,id=vda,cache=none,format=raw \
        -device virtio-blk-pci,drive=vda \
        -netdev user,id=net0,hostfwd=tcp::2222-:22 \
        -device virtio-net-pci,netdev=net0,mac=de:ad:be:ef:41:49 \
    $BRIDGE_IF \
        -display none \
    -serial $CONSOLE \
    -qmp unix:/var/run/qmp,server,nowait \
    -append "console=ttyAMA0 root=/dev/vda rw $CMDLINE"