#!/bin/bash
# qemu_gdb_attach.sh - Launch QEMU with GDB server for guest kernel debugging
# Usage: ./qemu_gdb_attach.sh [gdb_port] [freeze_at_start]

set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
BASE_DIR="$(cd "$SCRIPT_DIR/.." && pwd)"

GDB_PORT="${1:-1234}"
FREEZE="${2:-true}"  # -S flag to freeze at startup

# Default QEMU command from launch_qemu_vgpu.sh
QEMU_CMD=(
    qemu-system-x86_64
    -enable-kvm
    -cpu host
    -smp 4
    -m 8G
    -device vfio-pci,sysfsdev=/sys/bus/mdev/devices/$(cat /sys/bus/mdev/devices/*/uuid 2>/dev/null | head -1),display=off
    -drive file=/var/lib/libvirt/images/ubuntu-vgpu.qcow2,format=qcow2,if=virtio
    -netdev user,id=net0,hostfwd=tcp::2222-:22
    -device virtio-net-pci,netdev=net0
    -nographic
    -serial mon:stdio
)

# Add GDB server options
if [[ "$FREEZE" == "true" ]]; then
    QEMU_CMD+=(-s -S)  # -s = gdbserver on :1234, -S = freeze at startup
else
    QEMU_CMD+=(-s)     # -s = gdbserver on :1234, run normally
fi

# Override port if specified
if [[ "$GDB_PORT" != "1234" ]]; then
    QEMU_CMD+=(-gdb "tcp::$GDB_PORT")
fi

echo "=========================================="
echo "QEMU GDB Debug Launch"
echo "=========================================="
echo "GDB Port: $GDB_PORT"
echo "Freeze at start: $FREEZE"
echo "QEMU Command: ${QEMU_CMD[*]}"
echo ""
echo "In another terminal, connect with:"
echo "  gdb ./vmlinux"
echo "  (gdb) target remote localhost:$GDB_PORT"
echo "  (gdb) break nvidia_probe"
echo "  (gdb) continue"
echo ""
echo "Or use the GDB script:"
echo "  gdb -x $BASE_DIR/tools/gdb_scripts/nvidia_init.gdb ./vmlinux"
echo ""

# Launch QEMU
exec "${QEMU_CMD[@]}"