From bcbb0dabf55d8b82a0b856c6e39458d42e933444 Mon Sep 17 00:00:00 2001
From: Norman Feske <norman.feske@genode-labs.com>
Date: Thu, 15 May 2014 12:09:16 +0200
Subject: [PATCH] Build-system support for creating host tools

---
 repos/base/mk/generic.mk | 9 +++++----
 repos/base/mk/global.mk  | 2 ++
 repos/base/mk/lib.mk     | 9 +++++++++
 repos/base/mk/prg.mk     | 5 +++++
 4 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/repos/base/mk/generic.mk b/repos/base/mk/generic.mk
index 8f865ead13..aa2a897cb7 100644
--- a/repos/base/mk/generic.mk
+++ b/repos/base/mk/generic.mk
@@ -24,20 +24,21 @@ $(SUB_DIRS):
 	$(VERBOSE)mkdir -p $@
 
 #
-# Make sure, that we rebuild object files after Makefile changes
+# Make sure that we rebuild object files and host tools after Makefile changes
 #
-$(wildcard $(OBJECTS)): $(filter-out $(LIB_PROGRESS_LOG),$(MAKEFILE_LIST))
+$(wildcard $(OBJECTS)) $(HOST_TOOLS): $(filter-out $(LIB_PROGRESS_LOG),$(MAKEFILE_LIST))
 
 INCLUDES := $(addprefix -I,$(wildcard $(ALL_INC_DIR)))
 
 #
 # If one of the 3rd-party ports used by the target changed, we need to rebuild
-# all object files because they may include headers from the 3rd-party port.
+# all object files and host tools because they may include sources from the
+# 3rd-party port.
 #
 # The 'PORT_HASH_FILES' variable is populated as side effect of calling the
 # 'select_from_ports' function.
 #
-$(OBJECTS): $(PORT_HASH_FILES)
+$(OBJECTS) $(HOST_TOOLS): $(PORT_HASH_FILES)
 
 #
 # Include dependency files for the corresponding object files except
diff --git a/repos/base/mk/global.mk b/repos/base/mk/global.mk
index 08b7adbc88..3d95ebcc3d 100644
--- a/repos/base/mk/global.mk
+++ b/repos/base/mk/global.mk
@@ -21,6 +21,7 @@ CUSTOM_NM      ?= $(CROSS_DEV_PREFIX)nm
 CUSTOM_OBJCOPY ?= $(CROSS_DEV_PREFIX)objcopy
 CUSTOM_RANLIB  ?= $(CROSS_DEV_PREFIX)ranlib
 CUSTOM_STRIP   ?= $(CROSS_DEV_PREFIX)strip
+CUSTOM_HOST_CC ?= gcc
 
 #
 # GNU utilities
@@ -45,6 +46,7 @@ NM      = $(CUSTOM_NM)
 OBJCOPY = $(CUSTOM_OBJCOPY)
 RANLIB  = $(CUSTOM_RANLIB)
 STRIP   = $(CUSTOM_STRIP)
+HOST_CC = $(CUSTOM_HOST_CC)
 
 #
 # Compiler and Linker options
diff --git a/repos/base/mk/lib.mk b/repos/base/mk/lib.mk
index 7db6a655dc..d51d7a1757 100644
--- a/repos/base/mk/lib.mk
+++ b/repos/base/mk/lib.mk
@@ -109,6 +109,15 @@ message:
 #
 all: $(LIB_TAG)
 
+#
+# Trigger the build of host tools
+#
+# We make '$(LIB_TAG)' depend on the host tools to support building host tools
+# from pseudo libraries with no actual source code. In this case '$(OBJECTS)'
+# is empty.
+#
+$(LIB_TAG) $(OBJECTS): $(HOST_TOOLS)
+
 $(LIB_TAG): $(LIB_A) $(LIB_SO) $(INSTALL_SO)
 	@touch $@
 
diff --git a/repos/base/mk/prg.mk b/repos/base/mk/prg.mk
index 82e5d6de0a..3ca2cc8b61 100644
--- a/repos/base/mk/prg.mk
+++ b/repos/base/mk/prg.mk
@@ -181,6 +181,11 @@ endif
 LINK_ITEMS       := $(OBJECTS) $(STATIC_LIBS) $(SHARED_LIBS)
 SHORT_LINK_ITEMS := $(subst $(LIB_CACHE_DIR),$$libs,$(LINK_ITEMS))
 
+#
+# Trigger the build of host tools
+#
+$(LINK_ITEMS) $(TARGET): $(HOST_TOOLS)
+
 LD_CMD += -Wl,--whole-archive -Wl,--start-group
 LD_CMD += $(SHORT_LINK_ITEMS)
 LD_CMD += $(EXT_OBJECTS)