From af4d848144d3e62a429528149dc33fd8d45ec9da Mon Sep 17 00:00:00 2001
From: Jimmy Brisson <theotherjimmy@gmail.com>
Date: Wed, 1 Feb 2017 15:59:27 -0600
Subject: [PATCH 1/2] Use the C Pre-Processor on GCC Linker scirpts

This allows us to define parts of the linker script outside of the
linker script itself. In particular, we are interested in restricting
ROM to a subsection.
---
 tools/toolchains/gcc.py | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/tools/toolchains/gcc.py b/tools/toolchains/gcc.py
index 3186cbb76ff..54fdbd567c5 100644
--- a/tools/toolchains/gcc.py
+++ b/tools/toolchains/gcc.py
@@ -15,7 +15,7 @@
 limitations under the License.
 """
 import re
-from os.path import join, basename, splitext
+from os.path import join, basename, splitext, dirname
 
 from tools.toolchains import mbedToolchain, TOOLCHAIN_PATHS
 from tools.hooks import hook_tool
@@ -93,6 +93,7 @@ def __init__(self, target,  notify=None, macros=None,
         self.flags['ld'] += self.cpu
         self.ld = [join(tool_path, "arm-none-eabi-gcc")] + self.flags['ld']
         self.sys_libs = ["stdc++", "supc++", "m", "c", "gcc"]
+        self.preproc = [join(tool_path, "arm-none-eabi-cpp"), "-E", "-P"]
 
         self.ar = join(tool_path, "arm-none-eabi-ar")
         self.elf2bin = join(tool_path, "arm-none-eabi-objcopy")
@@ -213,6 +214,15 @@ def link(self, output, objects, libraries, lib_dirs, mem_map):
             libs.append("-l%s" % name[3:])
         libs.extend(["-l%s" % l for l in self.sys_libs])
 
+        # Preprocess
+        if mem_map:
+            preproc_output = join(dirname(output), ".link_script.ld")
+            cmd = (self.preproc + [mem_map] + self.ld[1:] +
+                   [ "-o", preproc_output])
+            self.cc_verbose("Preproc: %s" % ' '.join(cmd))
+            self.default_cmd(cmd)
+            mem_map = preproc_output
+
         # Build linker command
         map_file = splitext(output)[0] + ".map"
         cmd = self.ld + ["-o", output, "-Wl,-Map=%s" % map_file] + objects + ["-Wl,--start-group"] + libs + ["-Wl,--end-group"]

From 3155e71786dc556cf1124fb458ad5a124949da88 Mon Sep 17 00:00:00 2001
From: Jimmy Brisson <theotherjimmy@gmail.com>
Date: Wed, 8 Feb 2017 17:04:17 -0600
Subject: [PATCH 2/2] Add pre-processing of linker scripts to Make exporter

For toolchains that do not implicitly run the C pre-processor on their
linker scripts the toolchain is expected to define a `preproc`
attribute.  The Makefiles then pick up on this attribute and add another
rule for pre-processing the linker script automatically.
---
 tools/export/makefile/Makefile.tmpl | 10 +++++++++-
 tools/export/makefile/__init__.py   |  8 ++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/tools/export/makefile/Makefile.tmpl b/tools/export/makefile/Makefile.tmpl
index 31316034d12..15d97f693de 100644
--- a/tools/export/makefile/Makefile.tmpl
+++ b/tools/export/makefile/Makefile.tmpl
@@ -67,6 +67,9 @@ CC      = {{cc_cmd}}
 CPP     = {{cppc_cmd}}
 LD      = {{ld_cmd}}
 ELF2BIN = {{elf2bin_cmd}}
+{% if pp_cmd -%}
+PREPROC = {{pp_cmd}}
+{%- endif %}
 {% if hex_files %}
 SREC_CAT = srec_cat
 {%- endif %}
@@ -119,8 +122,13 @@ all: $(PROJECT).bin $(PROJECT).hex size
 	+@echo "Compile: $(notdir $<)"
 	@$(CPP) $(CXX_FLAGS) $(INCLUDE_PATHS) -o $@ $<
 
+{% if pp_cmd %}
+$(PROJECT).link_script{{link_script_ext}}: $(LINKER_SCRIPT)
+	@$(PREPROC) $< -o $@
+{% endif %}
+
 {% block target_project_elf %}
-$(PROJECT).elf: $(OBJECTS) $(SYS_OBJECTS) $(LINKER_SCRIPT)
+$(PROJECT).elf: $(OBJECTS) $(SYS_OBJECTS) {% if pp_cmd -%} $(PROJECT).link_script{{link_script_ext}} {% else%} $(LINKER_SCRIPT) {% endif %}
 	+@echo "link: $(notdir $@)"
 	@$(LD) $(LD_FLAGS) {{link_script_option}} $(filter %{{link_script_ext}}, $^) $(LIBRARY_PATHS) --output $@ $(filter %.o, $^) $(LIBRARIES) $(LD_SYS_LIBS)
 {% endblock %}
diff --git a/tools/export/makefile/__init__.py b/tools/export/makefile/__init__.py
index d9c34a95b66..c6a1512094d 100644
--- a/tools/export/makefile/__init__.py
+++ b/tools/export/makefile/__init__.py
@@ -87,6 +87,14 @@ def generate(self):
             'user_library_flag': self.USER_LIBRARY_FLAG,
         }
 
+        if hasattr(self.toolchain, "preproc"):
+            ctx['pp_cmd'] = " ".join(["\'" + part + "\'" for part
+                                      in ([basename(self.toolchain.preproc[0])] +
+                                          self.toolchain.preproc[1:] + 
+                                          self.toolchain.ld[1:])])
+        else:
+            ctx['pp_cmd'] = None
+
         for key in ['include_paths', 'library_paths', 'linker_script',
                     'hex_files']:
             if isinstance(ctx[key], list):