From 5e5eafaa9a2aef42f92254aaa98aaa407813876a Mon Sep 17 00:00:00 2001 From: Heinrich Toews Date: Tue, 21 Apr 2026 11:53:16 +0200 Subject: [PATCH] arm64: dts: pfc-am62x: reserve U-Boot IPC sidecar shared memory Reserve 4 KB at 0x9c900000 (uboot-ipc-shm) in the Linux device tree so the kernel never allocates pages over the DDR region that U-Boot uses to pass LED commands to the M4 Zephyr firmware via the sidecar IPC channel. This region is written exclusively by U-Boot (A53) and read by the M4. Linux only needs to know to stay away from it. Signed-off-by: Heinrich Toews --- .../boot/dts/ti/k3-am623-pfc-750-8xxx-common.dtsi | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/arch/arm64/boot/dts/ti/k3-am623-pfc-750-8xxx-common.dtsi b/arch/arm64/boot/dts/ti/k3-am623-pfc-750-8xxx-common.dtsi index 2edc1805bf2e..2139e851dcfe 100644 --- a/arch/arm64/boot/dts/ti/k3-am623-pfc-750-8xxx-common.dtsi +++ b/arch/arm64/boot/dts/ti/k3-am623-pfc-750-8xxx-common.dtsi @@ -110,6 +110,17 @@ no-map; }; + /* + * U-Boot IPC side-door shared memory. + * Written by U-Boot (A53) to send LED commands to the M4. + * Must not be touched by the Linux kernel. + * See UBOOT_IPC_SHMEM_PHYS in wago_m4_led_protocol.h. + */ + uboot_ipc_shm: uboot-ipc-shm@9cbff000 { + reg = <0x00 0x9cbff000 0x00 0x1000>; + no-map; + }; + mcu_m4fss_dma_memory_region: m4f-dma-memory@9cb00000 { compatible = "shared-dma-pool"; reg = <0x00 0x9cb00000 0x00 0x100000>;