pylibfdt: Link extension module with libfdt rather than rebuilding

Currently we build the Python extension module from all the libfdt source
files as well as the swig wrapper file.  This is a bit silly, since we've
already compiled libfdt itself.

This changes the build to instead build the extension module from just the
swig wrapper, linking it against the libfdt.a we've already build.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Simon Glass <sjg@chromium.org>

pylibfdt/Makefile.pylibfdt

@@ -1,22 +1,20 @@
 # Makefile.pylibfdt
 #
 
-PYLIBFDT_srcs = $(addprefix $(LIBFDT_srcdir)/,$(LIBFDT_SRCS)) \
-		$(PYLIBFDT_srcdir)/libfdt.i
+PYLIBFDT_srcs = $(PYLIBFDT_srcdir)/libfdt.i
 PYMODULE = $(PYLIBFDT_objdir)/_libfdt.so
 
 define run_setup
-	SOURCES="$(1)" CPPFLAGS="$(CPPFLAGS)" VERSION="$(dtc_version)"
-	$(PYLIBFDT_objdir)/setup.py --quiet $(2)
+	CPPFLAGS="$(CPPFLAGS)" VERSION="$(dtc_version)"
+	$(PYLIBFDT_objdir)/setup.py --quiet $(1)
 endef
 
-$(PYMODULE): $(PYLIBFDT_srcs)
+$(PYMODULE): $(PYLIBFDT_srcs) $(LIBFDT_archive)
 	@$(VECHO) PYMOD $@
-	$(call run_setup, $^, build_ext --build-lib=$(PYLIBFDT_objdir))
+	$(call run_setup, build_ext --build-lib=$(PYLIBFDT_objdir))
 
 install_pylibfdt: $(PYMODULE)
 	$(VECHO) INSTALL-PYLIB; \
-	$(call run_setup, $(PYLIBFDT_srcs), \
-		install $(if $(SETUP_PREFIX),--prefix=$(SETUP_PREFIX)))
+	$(call run_setup, install $(if $(SETUP_PREFIX),--prefix=$(SETUP_PREFIX)))
 
 PYLIBFDT_cleanfiles = libfdt_wrap.c libfdt.py libfdt.pyc _libfdt.so

pylibfdt/setup.py

@@ -5,7 +5,6 @@ setup.py file for SWIG libfdt
 Copyright (C) 2017 Google, Inc.
 Written by Simon Glass <sjg@chromium.org>
 
-Files to be built into the extension are provided in SOURCES
 C flags to use are provided in CPPFLAGS
 Version is provided in VERSION
 
@@ -70,35 +69,31 @@ def GetEnvFromMakefiles():
     Returns:
         Tuple with:
             Version string
-            List of files to build
             List of extra C preprocessor flags needed
     """
     basedir = os.path.dirname(os.path.dirname(os.path.abspath(sys.argv[0])))
     makevars = ParseMakefile(os.path.join(basedir, 'Makefile'))
     version = '%s.%s.%s' % (makevars['VERSION'], makevars['PATCHLEVEL'],
                             makevars['SUBLEVEL'])
-    makevars = ParseMakefile(os.path.join(basedir, 'libfdt', 'Makefile.libfdt'))
-    files = makevars['LIBFDT_SRCS'].split()
-    files = [os.path.join(basedir, 'libfdt', fname) for fname in files]
-    files.append('pylibfdt/libfdt.i')
     cflags = ['-I%s/libfdt' % basedir]
-    return  version, files, cflags
+    return  version, cflags
 
 
 progname = sys.argv[0]
-files = os.environ.get('SOURCES', '').split()
 cflags = os.environ.get('CPPFLAGS', '').split()
 version = os.environ.get('VERSION')
 
 # If we were called directly rather than through our Makefile (which is often
 # the case with Python module installation), read the settings from the
 # Makefile.
-if not all((version, files, cflags)):
-    version, files, cflags= GetEnvFromMakefiles()
+if not all((version, cflags)):
+    version, cflags= GetEnvFromMakefiles()
 
 libfdt_module = Extension(
     '_libfdt',
-    sources = files,
+    sources = ['pylibfdt/libfdt.i'],
+    libraries = ['fdt'],
+    library_dirs = ['libfdt'],
     extra_compile_args = cflags,
 )