nrf53_bsim: Provide shared memory buffer for IPC rpmsg backend

Provide the actual shared memory buffer for the
IPC rpmsg backend in this platform.

Signed-off-by: Alberto Escolar Piedras <[email protected]>

Author: aescolar

boards/posix/nrf_bsim/CMakeLists.txt

@@ -35,6 +35,12 @@ target_sources(native_simulator INTERFACE
 	common/trace_hook.c
 )
 
+if (CONFIG_IPC_SERVICE)
+	target_sources(native_simulator INTERFACE
+		ipc_backend.c
+	)
+endif()
+
 zephyr_include_directories(
   soc
   common

boards/posix/nrf_bsim/ipc_backend.c

@@ -0,0 +1,15 @@
+/*
+ * Copyright (c) 2023 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/*
+ * This buffer is the shared memory buffer for the RPMSG IPC backed
+ * in simulation.
+ * It must be at last as large as the size defined in device tree, but as it will be compiled in
+ * the native simulator runner context we cannot refer to DT itself to size it.
+ * The default buffer for this target is defined in
+ * boards/arm/nrf5340dk_nrf5340/nrf5340_shared_sram_planning_conf.dtsi
+ */
+char IPC0_shm_buffer[65536];