's'

tools/compat.py

@@ -90,11 +90,19 @@ def analyze_for_build(container_runtime: str) -> CompatReport:
 def resolve_gpu_mode(requested: str, dri_devices: List[str]) -> Tuple[str, List[str]]:
     """
     Map user --gpu-mode to an effective redroid mode and docker --device arguments.
-    auto -> host if DRI nodes exist, else guest.
+
+    auto -> guest by default (many servers have /dev/dri but host-EGL still breaks boot/adbd).
+    Set REDROID_USE_HOST_GPU=1 (or true/yes/on) with --gpu-mode auto to pass DRI + use host when nodes exist.
     """
     req = (requested or "auto").strip().lower()
     if req == "auto":
-        effective = "host" if dri_devices else "guest"
+        want_host = os.environ.get("REDROID_USE_HOST_GPU", "").strip().lower() in (
+            "1",
+            "true",
+            "yes",
+            "on",
+        )
+        effective = "host" if (want_host and dri_devices) else "guest"
     elif req == "host":
         effective = "host" if dri_devices else "guest"
     elif req == "guest":
@@ -126,7 +134,11 @@ def analyze_for_run(
         report.warnings.extend(build.warnings)
         report.notes.extend(build.notes)
         if dri:
-            report.notes.append("DRI present: {} — GPU passthrough can be used.".format(", ".join(dri)))
+            report.notes.append(
+                "DRI present: {} — for host GPU use --gpu-mode host or REDROID_USE_HOST_GPU=1 with --gpu-mode auto.".format(
+                    ", ".join(dri)
+                )
+            )
         elif platform.system() == "Linux":
             report.warnings.append(
                 "No /dev/dri render nodes: software GLES (guest) often black-screens or flickers on headless servers."
@@ -140,7 +152,11 @@ def analyze_for_run(
             "--gpu-mode host requested but no DRI devices found; falling back to guest."
         )
     if req == "auto" and not skip_check:
-        report.notes.append("Resolved --gpu-mode auto -> {}".format(effective))
+        report.notes.append(
+            "Resolved --gpu-mode auto -> {} (set REDROID_USE_HOST_GPU=1 to prefer host when DRI exists).".format(
+                effective
+            )
+        )
     if effective == "host" and not skip_check:
         report.notes.append(
             "GPU host mode: if ADB cannot connect (connection refused), Android may not have finished boot "
@@ -164,7 +180,7 @@ if __name__ == "__main__":
 
     ap = argparse.ArgumentParser(description="Host/runtime compatibility probe (same logic as run_redroid.py)")
     ap.add_argument("-c", "--container", default="docker", help="docker or podman")
-    ap.add_argument("--gpu-mode", default="auto", help="guest, host, or auto")
+    ap.add_argument("--gpu-mode", default="guest", help="guest, host, or auto")
     ns = ap.parse_args()
     rep, gpu_eff, dev_args = analyze_for_run(ns.container, ns.gpu_mode, skip_check=False)
     emit_compat_report(rep)