Add --entry option to linker cli utility.

ppci/binutils/linker.py

@@ -19,6 +19,7 @@ def link(
     debug=False,
     extra_symbols=None,
     libraries=None,
+    entry=None,
 ):
     """ Links the iterable of objects into one using the given layout.
 
@@ -33,6 +34,7 @@ def link(
         extra_symbols: a dict of extra symbols which can be used during
             linking.
         libraries: a list of libraries to use when searching for symbols.
+        entry: the entry symbol where execution should begin.
 
     Returns:
         The linked object file
@@ -72,6 +74,7 @@ def link(
         debug=debug,
         extra_symbols=extra_symbols,
         libraries=libraries,
+        entry_symbol_name=entry,
     )
     return output_obj
 
@@ -95,6 +98,7 @@ def link(
         debug=False,
         extra_symbols=None,
         libraries=None,
+        entry_symbol_name=None,
     ):
         """ Link together the given object files using the layout """
         assert isinstance(input_objects, (list, tuple))
@@ -111,9 +115,18 @@ def link(
         if debug:
             self.dst.debug_info = DebugInfo()
 
+        # Take entry symbol from layout if not specified alreay:
+        if not entry_symbol_name and layout and layout.entry:
+            # TODO: what to do if two symbols are defined?
+            # for now the symbol given via command line overrides
+            # the entry in the linker script.
+            entry_symbol_name = layout.entry.symbol_name
+
         # Define entry symbol:
-        if layout and layout.entry:
-            self.dst.entry_symbol_id = self.inject_symbol(layout.entry.symbol_name, 'global', None, None).id
+        if entry_symbol_name:
+            self.dst.entry_symbol_id = self.inject_symbol(
+                entry_symbol_name, "global", None, None
+            ).id
 
         # Define extra symbols:
         extra_symbols = extra_symbols or {}
@@ -243,10 +256,12 @@ def inject_object(self, obj, debug):
         # Merge entry symbol:
         if obj.entry_symbol_id is not None:
             if self.dst.entry_symbol_id is None:
-                self.dst.entry_symbol_id = symbol_id_mapping[obj.entry_symbol_id]
+                self.dst.entry_symbol_id = symbol_id_mapping[
+                    obj.entry_symbol_id
+                ]
             else:
                 # TODO: improve error message?
-                raise CompilerError('Multiple entry points defined')
+                raise CompilerError("Multiple entry points defined")
 
         # Merge debug info:
         if debug and obj.debug_info:
@@ -593,7 +608,11 @@ def count_holes(offset, holes):
 
     def do_relocations(self):
         """ Perform the correct relocation as listed """
-        self.logger.debug("Performing {} linker relocations".format(len(self.dst.relocations)))
+        self.logger.debug(
+            "Performing {} linker relocations".format(
+                len(self.dst.relocations)
+            )
+        )
         for reloc in self.dst.relocations:
             self._do_relocation(reloc)
 

ppci/cli/link.py

@@ -38,8 +38,17 @@
     "-g", help="retain debug information", action="store_true", default=False
 )
 parser.add_argument(
-    '--relocatable',
-    "-r", help="Generate relocatable output", action="store_true", default=False
+    "--relocatable",
+    "-r",
+    help="Generate relocatable output",
+    action="store_true",
+    default=False,
+)
+parser.add_argument(
+    "--entry",
+    "-e",
+    help="Use entry as the starting symbol of execution of the program.",
+    default=None,
 )
 
 
@@ -48,24 +57,30 @@ def link(args=None):
     args = parser.parse_args(args)
     relocatable = args.relocatable
     with LogSetup(args):
-        obj = api.link(args.obj, layout=args.layout, debug=args.g, partial_link=relocatable)
+        obj = api.link(
+            args.obj,
+            layout=args.layout,
+            debug=args.g,
+            partial_link=relocatable,
+            entry=args.entry,
+        )
         if relocatable:
             with open(args.output, "w") as output:
                 obj.save(output)
         else:
             create_platform_executable(obj, args.output)
-            
+
 
 def create_platform_executable(obj, output_filename):
     """ Produce platform binary by spitting out exe/elf file. """
-    if sys.platform == 'linux':
+    if sys.platform == "linux":
         executable_filename = output_filename
-        api.objcopy(obj, None, 'elf', executable_filename)
+        api.objcopy(obj, None, "elf", executable_filename)
     else:
         # TODO: create windows exe.
         # raise NotImplementedError('Executable output not support for platform: {}'.format(sys.platform))
         executable_filename = output_filename
-        api.objcopy(obj, None, 'elf', executable_filename)
+        api.objcopy(obj, None, "elf", executable_filename)
 
 
 if __name__ == "__main__":