From 8afecd7cc048c2793c92259c0f8e9f768efff2f8 Mon Sep 17 00:00:00 2001
From: CMGS <ilskdw@gmail.com>
Date: Tue, 15 Sep 2026 19:46:11 +0800
Subject: [PATCH] boot: enable fanotify in the guest kernel

x86_64_defconfig leaves CONFIG_FANOTIFY off, so fanotify_init() returns
ENOSYS inside every sandbox and userspace file monitors that rely on it
(an OSWorld task's save-file watcher, scanner-style tools) cannot start.
Notification-only fanotify is software-only: no boot-time cost and no
work without a listener.
---
 boot/kernel/sandbox.config | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/boot/kernel/sandbox.config b/boot/kernel/sandbox.config
index d22133a9..bf99bee1 100644
--- a/boot/kernel/sandbox.config
+++ b/boot/kernel/sandbox.config
@@ -49,6 +49,10 @@ CONFIG_AUTOFS_FS=y
 CONFIG_DEVTMPFS=y
 CONFIG_DEVTMPFS_MOUNT=y
 CONFIG_BLK_DEV_INITRD=y
+
+## fanotify for userspace file monitors; defconfig leaves it off and
+## fanotify_init() answers ENOSYS. Software-only: no listener, no work.
+CONFIG_FANOTIFY=y
 # Entropy: since 6.2 the kernel trusts CPU/bootloader seeds by default
 # (random.trust_cpu removed as a Kconfig) — no boot-time entropy stall.