#!/usr/bin/env bash

set -e

# CLI handling.
arch=x86_64
debug_vm=''
kgdb=false
nographic=false
# norandmaps: Don't use address space randomization. Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space.
# printk.time=y: log in format: "[time ] msg" for all printk messages.
# nokaslr: https://unix.stackexchange.com/questions/397939/turning-off-kaslr-to-debug-linux-kernel-using-qemu-and-gdb
#   Turned on by default since v4.12
extra_append='nokaslr norandmaps printk.devkmsg=on printk.time=y'
extra_flags=''
gem5=false
gem5opts=''
initrd=false
root=''
while getopts a:Dde:G:giknt:x OPT; do
  case "$OPT" in
    a)
      arch="$OPTARG"
      ;;
    d)
      extra_flags="$extra_flags -S -s"
      ;;
    D)
      debug_vm='gdb -q -ex start --args'
      ;;
    e)
      extra_append="$extra_append $OPTARG"
      ;;
    k)
      extra_append="$extra_append kgdbwait"
      # For those who want to try KDB.
      #extra_append="$extra_append kgdbwait kgdboc=kbd"
      extra_flags="$extra_flags -serial tcp::1234,server,nowait"
      kgdb=true
      ;;
    g)
      gem5=true
      ;;
    G)
      gem5opts="$OPTARG"
      ;;
    i)
      initrd=true
      ;;
    n)
      extra_append="$extra_append console=ttyS0"
      extra_flags="$extra_flags -nographic"
      nographic=true
      ;;
  esac
done
shift "$(($OPTIND - 1))"
extra_flags="$extra_flags $@"

if $gem5; then
  outdir="$(pwd)/buildroot/output.${arch}-gem5~"
  gem5_dir="$(pwd)/gem5/gem5"
  if [ "$arch" = x86_64 ]; then
    cmd="\
M5_PATH='$(pwd)/gem5/gem5-system' \
'${gem5_dir}/build/X86/gem5.opt' \
${gem5opts} \
'${gem5_dir}/configs/example/fs.py' \
--disk-image='${outdir}/images/rootfs.ext2' \
--kernel='${outdir}/build/linux-custom/vmlinux' \
--root-device=/dev/sda \
"
  elif [ "$arch" = arm ] || [ "$arch" = aarch64 ]; then
    cmd="\
M5_PATH='$(pwd)/gem5/gem5-system' \
$debug_vm \
'${gem5_dir}/build/ARM/gem5.opt' \
${gem5opts} \
'${gem5_dir}/configs/example/fs.py' \
--command-line='earlyprintk=pl011,0x1c090000 console=ttyAMA0 lpj=19988480 rw loglevel=8 mem=512MB root=/dev/sda $extra_append' \
--disk-image='${outdir}/images/rootfs.ext2' \
--dtb-file='${gem5_dir}/system/arm/dt/$([ "$arch" = arm ] && echo armv7_gem5_v1_1cpu || echo armv8_gem5_v1_1cpu).dtb' \
--kernel='${outdir}/build/linux-custom/vmlinux' \
--machine-type=VExpress_GEM5_V1 \
"
  fi
  cmd="$cmd \"\$@\""
else
  buildroot_out_dir="./buildroot/output.${arch}~"
  images_dir="$buildroot_out_dir/images"
  qemu_common="\
$debug_vm \
$buildroot_out_dir/host/usr/bin/qemu-system-${arch} \
-m 128M \
-monitor telnet::45454,server,nowait \
-netdev user,hostfwd=tcp::45455-:45455,id=net0 \
-smp 1 \
"
  if $initrd; then
    extra_flags="$extra_flags -initrd '${images_dir}/rootfs.cpio'"
  fi
  # The base QEMU commands are found under board/qemu/*/readme.tx
  case "$arch" in
    x86_64)
      if $kgdb; then
        extra_append="$extra_append kgdboc=ttyS0,115200"
      fi
      if ! $initrd; then
        root='root=/dev/vda'
        extra_flags="$extra_flags -drive file='${images_dir}/rootfs.ext2.qcow2,if=virtio,format=qcow2'"
      fi
      cmd="$qemu_common \
-M pc \
-append '$root nopat $extra_append' \
-device edu \
-device lkmc_pci_min \
-device virtio-net-pci,netdev=net0 \
-kernel ${images_dir}/bzImage \
$extra_flags \
"
    ;;
    arm)
      if $kgdb; then
        extra_append="$extra_append kgdboc=ttyAMA0,115200"
      fi
      if ! $initrd; then
        root='root=/dev/sda'
        extra_flags="$extra_flags -drive file='${images_dir}/rootfs.ext2.qcow2,if=scsi,format=qcow2'"
      fi
      cmd="$qemu_common \
-M versatilepb \
-append '$root $extra_append' \
-device rtl8139,netdev=net0 \
-dtb ${images_dir}/versatile-pb.dtb \
-kernel ${images_dir}/zImage \
-serial stdio \
$extra_flags \
"
    ;;
    aarch64)
      if $kgdb; then
        extra_append="$extra_append kgdboc=ttyAMA0,115200"
      fi
      cmd="$qemu_common \
-M virt \
-append 'root=/dev/sda $extra_append' \
-cpu cortex-a57 \
-device virtio-net-device,netdev=net0 \
-kernel ${images_dir}/Image \
-nographic \
-serial stdio \
$extra_flags \
"
    ;;
    mips64)
      if ! $initrd; then
        root='root=/dev/hda'
        extra_flags="$extra_flags -drive file='${images_dir}/rootfs.ext2.qcow2,format=qcow2'"
      fi
      cmd="$qemu_common \
-M malta \
-append 'root=/dev/hda $extra_append' \
-cpu I6400 \
-device pcnet \
-kernel ${images_dir}/vmlinux \
-nographic \
$extra_flags \
"
    ;;
  esac
fi


echo "$cmd"
eval "$cmd"