diff --git a/target/linux/mediatek/patches-6.12/199-arm64-dts-mediatek-mt7986-increase-ATF-reserved-memo.patch b/target/linux/mediatek/patches-6.12/199-arm64-dts-mediatek-mt7986-increase-ATF-reserved-memo.patch
new file mode 100644
index 0000000000..8cef5ba442
--- /dev/null
+++ b/target/linux/mediatek/patches-6.12/199-arm64-dts-mediatek-mt7986-increase-ATF-reserved-memo.patch
@@ -0,0 +1,29 @@
+From 236317dd4e55512933dcdaec3d0b4a0824f5e5bd Mon Sep 17 00:00:00 2001
+From: Shiji Yang <yangshiji66@outlook.com>
+Date: Sun, 10 Aug 2025 18:11:01 +0800
+Subject: [PATCH] arm64: dts: mediatek: mt7986: increase ATF reserved memory to
+ 256 kiB
+
+The latest Mediatek open-source Trusted Firmware-A project has
+reserved 256 KiB for BL2 and BL31. It is better to increase the
+reserved memory region in the Linux kernel to protect the data.
+
+Signed-off-by: Shiji Yang <yangshiji66@outlook.com>
+---
+ arch/arm64/boot/dts/mediatek/mt7986a.dtsi | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+--- a/arch/arm64/boot/dts/mediatek/mt7986a.dtsi
++++ b/arch/arm64/boot/dts/mediatek/mt7986a.dtsi
+@@ -76,9 +76,9 @@
+ 			record-size = <0x1000>;
+ 		};
+ 
+-		/* 192 KiB reserved for ARM Trusted Firmware (BL31) */
++		/* 256 KiB reserved for ARM Trusted Firmware (BL31 + BL32) */
+ 		secmon_reserved: secmon@43000000 {
+-			reg = <0 0x43000000 0 0x30000>;
++			reg = <0 0x43000000 0 0x40000>;
+ 			no-map;
+ 		};
+