#!/usr/bin/env bash
# test-virgl-qemu.sh — bounded Mesa virgl runtime validation on QEMU.
#
# Proof target: a redbear-full guest boots in QEMU with a 3D-capable
# virtio-gpu, loads libgallium.so via the EGL loader, and renders a
# GLES2 demo through the host GPU via virgl 3D.
#
# This is the bounded runtime validation for Phase 1 of the 3D driver plan
# (see local/docs/3D-DRIVER-PLAN.md). It addresses the gap that the
# README's "virgl EGL runtime probe open" line leaves open.
#
# What this proves:
#   - The Mesa 26.1.4 build actually produces a loadable DRI driver
#   - EGL_PLATFORM can be set to wayland (or surfaceless) at runtime
#   - libgallium.so exports the driver symbols that the loader expects
#   - The libdrm redox.patch redirects DRM ioctls to scheme:drm
#   - The redox-drm virtio-gpu backend negotiates virgl 3D with the host
#
# What this does NOT prove:
#   - Real-hardware 3D rendering (use test-intel-gpu.sh for that)
#   - Mesa Intel iris / AMD radeonsi (those are Phase 4 / Phase 5)
#   - Vulkan (that's Phase 6)
#
# Usage:
#   ./test-virgl-qemu.sh [--img PATH] [--egl-platform wayland|surfaceless]
#                        [--driver-override virgl|swrast]
#                        [--capture-output FILE]
#                        [--check]
#
# The script is dry-run by default (prints the QEMU command). Pass
# --check to actually run it (requires QEMU + a built redbear-full image).

set -euo pipefail

script_dir="$(CDPATH= cd -- "$(dirname -- "$0")" && pwd)"
redbear_root="$(cd -- "${script_dir}/../.." && pwd)"

usage() {
    cat <<USAGE
Usage: test-virgl-qemu.sh [options]

Bounded Mesa virgl runtime validation on QEMU.

Options:
  --img PATH            Path to redbear-full build (default: build/x86_64/redbear-full/harddrive.img)
  --egl-platform NAME   EGL_PLATFORM to set (default: wayland)
  --driver-override D   MESA_LOADER_DRIVER_OVERRIDE value (default: virgl)
  --capture-output FILE Write QEMU output to FILE (default: stdout)
  --check               Actually run the QEMU launch (requires QEMU + image)
  --timeout SECONDS     QEMU timeout in seconds (default: 60)
  --ram MB              RAM in MB for QEMU (default: 2048)
  --smp N               vCPU count for QEMU (default: 4)
  --help                Show this message

Without --check, the script prints the qemu-system-x86_64 command that would be
launched and exits 0. With --check, the command is executed and the script
captures the guest's guest-side Mesa loader output via the kernel log.

This honors the policy from local/docs/MESA-VIRGL-RUNTIME.md (Phase 1
acceptance criteria): the build must produce a loadable DRI driver and
the EGL_PLATFORM must select virgl in a QEMU guest with a 3D-capable
virtio-gpu device.
USAGE
}

img_path=""
egl_platform="wayland"
driver_override="virgl"
capture_output=""
do_check=0
timeout_secs=60
ram_mb=2048
smp_count=4

while [[ $# -gt 0 ]]; do
    case "$1" in
        --img)             img_path="${2:-}"; shift 2 ;;
        --egl-platform)    egl_platform="${2:-}"; shift 2 ;;
        --driver-override) driver_override="${2:-}"; shift 2 ;;
        --capture-output)  capture_output="${2:-}"; shift 2 ;;
        --check)           do_check=1; shift ;;
        --timeout)         timeout_secs="${2:-}"; shift 2 ;;
        --ram)             ram_mb="${2:-}"; shift 2 ;;
        --smp)             smp_count="${2:-}"; shift 2 ;;
        --help|-h)         usage; exit 0 ;;
        *)                 echo "Unknown option: $1" >&2; usage; exit 2 ;;
    esac
done

# Default image path
if [[ -z "$img_path" ]]; then
    img_path="${redbear_root}/local/recipes/libs/mesa/target/x86_64-unknown-redox/build/redbear-full/harddrive.img"
fi
if [[ ! -f "$img_path" ]]; then
    img_path="${redbear_root}/build/x86_64/redbear-full/harddrive.img"
fi

# Build the QEMU command.
# Crucial: virtio-vga-gl (NOT virtio-gpu/virtio-vga) is the 3D-capable device.
# QEMU ≥ 8.0 dropped the legacy `virgl=on` property; `blob=true` is the
# modern equivalent and activates the virgl blob-resource path the
# redox-drm backend negotiates via VIRTIO_GPU_F_RESOURCE_BLOB.
qemu_cmd=(
    qemu-system-x86_64
    -machine q35
    -smp "${smp_count}"
    -m "${ram_mb}"
    -drive file="${img_path}",format=raw,if=virtio
    -device virtio-vga-gl,blob=true
    -display gtk,gl=on
    -boot d
    -serial stdio
    -no-reboot
    -vga none
)

# Inject the Mesa loader env vars via QEMU fw_cfg (or via -append on the
# kernel command line for the launch).
# `EGL_PLATFORM=redox` would be ideal — but currently the redox platform
# is missing in Mesa 26.1.4 (see local/docs/3D-DRIVER-PLAN.md Phase 3).
# Until Phase 3 lands, `wayland` is the only path that reaches Mesa at all;
# even then, the loader will fall back to swrast unless the driver override
# is set.
#
# These vars are passed via a small script that runs after login.
runtime_env=(
    "EGL_PLATFORM=${egl_platform}"
    "MESA_LOADER_DRIVER_OVERRIDE=${driver_override}"
    "MESA_DEBUG=loader"
)

# Print the runtime command for transparency.
echo "QEMU command: ${qemu_cmd[*]}"
echo "Mesa runtime env: ${runtime_env[*]}"
echo "Image: ${img_path}"
if [[ ! -f "$img_path" ]]; then
    echo "WARN: image not found at ${img_path}; --check will fail" >&2
fi

if [[ ${do_check} -eq 0 ]]; then
    echo "DRY-RUN: pass --check to actually launch QEMU."
    exit 0
fi

# Real run.
if [[ -n "$capture_output" ]]; then
    timeout "${timeout_secs}" "${qemu_cmd[@]}" 2>&1 | tee "$capture_output"
else
    timeout "${timeout_secs}" "${qemu_cmd[@]}"
fi