From 9915b80e30167fddcd20cb3fde59bbd6172bf559 Mon Sep 17 00:00:00 2001
From: chao an <anchao@lixiang.com>
Date: Fri, 5 Jul 2024 00:13:45 +0800
Subject: [PATCH] arch/sim: add custom data section support

The link script of NuttX Simulator is generated through compilation
options. This PR will support configure special data sections in
kconfig to meet the support of 3rd party applications.

we need to follow the syntax of linker script. In 3rd-party applications, some data will be labeled as section:

| a.c:
| struct task_s a __attribute__((section(".data.custom.taska")));
| b.c:
| struct task_s b __attribute__((section(".data.custom.taskb")));

Data of the same type struct can be placed in a fixed location to reduce the overhead caused by searching:

|   .data           :
|   {
|     _custom_data_table_start = .;
|     KEEP(*(.data.custom.*))
|     _custom_data_table_end = .;
|   }

Such section declare can be configured via Kconfig in the PR:

| CONFIG_SIM_CUSTOM_DATA_SECTION=" .data : { _custom_data_table_start = .; KEEP(*(.data.custom.*)) _custom_data_table_end = .; } "

Signed-off-by: chao an <anchao@lixiang.com>
---
 CMakeLists.txt        | 4 +++-
 arch/sim/Kconfig      | 7 +++++++
 arch/sim/src/Makefile | 3 +++
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index c71f30fa0a6..b152fe01d2e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -695,7 +695,9 @@ else()
       COMMAND
         echo ARGS
         '__init_array_start = .\; __init_array_end = .\; __fini_array_start = .\; __fini_array_end = .\;'
-        >> nuttx.ld)
+        >> nuttx.ld
+      COMMAND sed -i '/\\.data *:/i " ${CONFIG_SIM_CUSTOM_DATA_SECTION} " '
+              nuttx.ld)
   endif()
 
   # conflicting symbols to rename
diff --git a/arch/sim/Kconfig b/arch/sim/Kconfig
index 29198010102..2be924136e5 100644
--- a/arch/sim/Kconfig
+++ b/arch/sim/Kconfig
@@ -794,4 +794,11 @@ config SIM_USB_PRIO
 
 endif
 
+config SIM_CUSTOM_DATA_SECTION
+	string "Custom data section name for Simulator"
+	default ""
+	---help---
+		Custom data section name for Simulator to allow
+		developer to define special data sections.
+
 endif # ARCH_SIM
diff --git a/arch/sim/src/Makefile b/arch/sim/src/Makefile
index 60cf7b8a4ea..d19c4b06dcb 100644
--- a/arch/sim/src/Makefile
+++ b/arch/sim/src/Makefile
@@ -414,6 +414,9 @@ ifeq ($(CONFIG_MM_KASAN_GLOBAL),y)
 	            .kasan.global : {KEEP(*(.data..LASAN0)) KEEP (*(.data.rel.local..LASAN0)) }\n  \
 	            .interp : {*(.interp)}/g' nuttx.ld
 endif
+ifneq ($(CONFIG_SIM_CUSTOM_DATA_SECTION),"")
+	$(Q) sed -i '/\.data *:/i $(subst ",, $(CONFIG_SIM_CUSTOM_DATA_SECTION))' nuttx.ld
+endif
 ifeq ($(CONFIG_ALLSYMS)$(CONFIG_MM_KASAN_GLOBAL),)
 	$(if $(CONFIG_HAVE_CXX),\
 	$(Q) "$(CXX)" $(CFLAGS) $(LDFLAGS) -o $(TOPDIR)/$@ $(HEADOBJ) nuttx.rel $(HOSTOBJS) $(STDLIBS),\