soc/integration: allow using builder with soc.cpu_type == None

litex/soc/integration/builder.py

@@ -133,6 +133,9 @@ class Builder:
     def build(self):
         self.soc.finalize()
 
+        os.makedirs(self.output_dir, exist_ok=True)
+
+        if self.soc.cpu_type is not None:
             if self.soc.integrated_rom_size and not self.compile_software:
                 raise ValueError("Software must be compiled in order to "
                                  "intitialize integrated ROM")
@@ -141,6 +144,7 @@ class Builder:
             self._generate_includes()
             self._generate_software()
             self._initialize_rom()
+
         if self.gateware_toolchain_path is None:
             kwargs = dict()
         else: