scripts: code_relocate: add option to inhibit .data relocation

This is activated by passing NOCOPY_DATA to zephyr_code_relocate().

It helps when building firmwares for coprocessors,
where the image is loaded completely into SRAM from Linux-land
using the remoteproc framework.

Fixes: #86530

Signed-off-by: Robin Haberkorn <haberkorn@metratec.com>

Author: rhaberkorn

cmake/modules/extensions.cmake

@@ -1446,13 +1446,15 @@ endmacro()
 # zephyr_code_relocate(LIBRARY my_lib SRAM)
 #
 # The following optional arguments are supported:
-# - NOCOPY: this flag indicates that the file data does not need to be copied
+# - NOCOPY: this flag indicates that the file's text section does not need to be copied
 #   at boot time (For example, for flash XIP).
+# - NOCOPY_DATA: this flag indicates that the file's data section (read-write data)
+#   does not need to be copied at boot time (For example, if it is directly loaded into SRAM).
 # - NOKEEP: suppress the generation of KEEP() statements in the linker script,
 #   to allow any unused code in the given files/library to be discarded.
 # - PHDR [program_header]: add program header. Used on Xtensa platforms.
 function(zephyr_code_relocate)
-  set(options NOCOPY NOKEEP)
+  set(options NOCOPY NOCOPY_DATA NOKEEP)
   set(single_args LIBRARY LOCATION PHDR FILTER)
   set(multi_args FILES)
   cmake_parse_arguments(CODE_REL "${options}" "${single_args}"
@@ -1516,6 +1518,11 @@ function(zephyr_code_relocate)
   else()
     set(flag_list NOCOPY)
   endif()
+  if(NOT CODE_REL_NOCOPY_DATA)
+    list(APPEND flag_list COPYDATA)
+  else()
+    list(APPEND flag_list NOCOPYDATA)
+  endif()
   if(CODE_REL_NOKEEP)
     list(APPEND flag_list NOKEEP)
   endif()

doc/kernel/code-relocation.rst

@@ -139,8 +139,8 @@ you can pass ``NOKEEP`` to your ``zephyr_code_relocate()`` call.
 The example above will help ensure that any unused code found in the .text
 sections of ``file1.c`` will not stick to SRAM2.
 
-NOCOPY flag
-===========
+NOCOPY and NOCOPY_DATA flags
+============================
 
 When a ``NOCOPY`` option is passed to the ``zephyr_code_relocate()`` function,
 the relocation code is not generated in ``code_relocation.c``. This flag can be
@@ -149,13 +149,18 @@ XIP area.
 
 This example will place the .text section of the ``xip_external_flash.c`` file
 to the ``EXTFLASH`` memory region where it will be executed from (XIP). The
-.data will be relocated as usual into SRAM.
+.data will be relocated as usual into SRAM, since flash in XIP mode does not
+allow random write access and variables do not have to persist.
 
   .. code-block:: none
 
      zephyr_code_relocate(FILES src/xip_external_flash.c LOCATION EXTFLASH_TEXT NOCOPY)
      zephyr_code_relocate(FILES src/xip_external_flash.c LOCATION SRAM_DATA)
 
+You can additionally specify ``NOCOPY_DATA`` if you do not want .data to be relocated into SRAM.
+This can be useful if it is already loaded into SRAM, e.g. by the Linux kernel
+using the `remoteproc framework <https://docs.kernel.org/staging/remoteproc.html>`_.
+
 Relocating libraries
 ====================
 

scripts/build/gen_relocate_app.py

@@ -32,8 +32,10 @@
 - If the memory type is appended with _DATA / _TEXT/ _RODATA/ _BSS only the
   selected memory is placed in the required memory region. Others are
   ignored.
-- COPY/NOCOPY defines whether the script should generate the relocation code in
-  code_relocation.c or not
+- COPY/NOCOPY defines whether the script should generate the relocation code for text segment
+  symbols in code_relocation.c or not
+- COPYDATA/NOCOPYDATA defines whether the script should generate the relocation code for data segment
+  symbols in code_relocation.c or not
 - NOKEEP will suppress the default behavior of marking every relocated symbol
   with KEEP() in the generated linker script.
 
@@ -389,9 +391,10 @@ def generate_linker_script(linker_file, sram_data_linker_file, sram_bss_linker_f
 
     for memory_type, full_list_of_sections in \
             sorted(complete_list_of_sections.items()):
-
-        is_copy = bool("|COPY" in memory_type)
-        memory_type = memory_type.split("|", 1)[0]
+        memory_type = memory_type.split("|")
+        is_copy = bool("COPY" in memory_type)
+        is_copy_data = bool("COPYDATA" in memory_type)
+        memory_type = memory_type[0]
 
         if region_is_default_ram(memory_type) and is_copy:
             gen_string += MPU_RO_REGION_START.format(memory_type.lower(), memory_type.upper())
@@ -404,10 +407,10 @@ def generate_linker_script(linker_file, sram_data_linker_file, sram_bss_linker_f
             gen_string += MPU_RO_REGION_END.format(memory_type.lower())
 
         if region_is_default_ram(memory_type):
-            gen_string_sram_data += string_create_helper(SectionKind.DATA, memory_type, full_list_of_sections, 1, 1, phdrs)
+            gen_string_sram_data += string_create_helper(SectionKind.DATA, memory_type, full_list_of_sections, 1, is_copy_data, phdrs)
             gen_string_sram_bss += string_create_helper(SectionKind.BSS, memory_type, full_list_of_sections, 0, 1, phdrs)
         else:
-            gen_string += string_create_helper(SectionKind.DATA, memory_type, full_list_of_sections, 1, 1, phdrs)
+            gen_string += string_create_helper(SectionKind.DATA, memory_type, full_list_of_sections, 1, is_copy_data, phdrs)
             gen_string += string_create_helper(SectionKind.BSS, memory_type, full_list_of_sections, 0, 1, phdrs)
 
     # finally writing to the linker file
@@ -623,10 +626,9 @@ def main():
 
     code_generation = {"copy_code": '', "zero_code": '', "extern": ''}
     for mem_type, list_of_sections in sorted(complete_list_of_sections.items()):
-
-        if "|COPY" in mem_type:
-            mem_type = mem_type.split("|", 1)[0]
-            code_generation = generate_memcpy_code(mem_type,
+        mem_type = mem_type.split("|")
+        if "COPY" in mem_type:
+            code_generation = generate_memcpy_code(mem_type[0],
                                                list_of_sections, code_generation)
 
     dump_header_file(args.output_code, code_generation)