From c801cb29d64764fa8082ec2ab17dd12f74b3143f Mon Sep 17 00:00:00 2001
From: Michael Brown
Date: Tue, 19 Aug 2014 16:17:25 +0100
Subject: [build] Allow for named configurations at build time

Allow named configurations to be specified via the CONFIG=... build
parameter.  For headers in config/*.h which support named
configurations, the following files will be included when building
with CONFIG=<name>:

  - config/defaults/<platform>.h (e.g. config/defaults/pcbios.h)

  - config/<header>.h

  - config/<name>/<header>.h (only if the directory config/<name> exists)

  - config/local/<header>.h (autocreated if necessary)

  - config/local/<name>/<header>.h (autocreated if necessary)

This mechanism allows for predefined named configurations to be
checked in to the source tree, as a directory config/<name> containing
all of the required header files.

The mechanism also allows for users to define multiple local
configurations, by creating header files in the directory
config/local/<name>.

Note that the config/*.h files which are used only to configure
internal iPXE APIs (e.g. config/ioapi.h) cannot be modified via a
named configuration.  This avoids rebuilding the entire iPXE codebase
whenever switching to a different named configuration.

Inspired-by: Robin Smidsrød <robin@smidsrod.no>
Tested-by: Robin Smidsrød <robin@smidsrod.no>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
---
 src/Makefile.housekeeping | 40 ++++++++++++++++++++++++++++++++++++++--
 1 file changed, 38 insertions(+), 2 deletions(-)

(limited to 'src/Makefile.housekeeping')

diff --git a/src/Makefile.housekeeping b/src/Makefile.housekeeping
index 0dce8d06..b07a8d96 100644
--- a/src/Makefile.housekeeping
+++ b/src/Makefile.housekeeping
@@ -689,6 +689,34 @@ privkey_DEPS += $(PRIVKEY_LIST)
 
 CFLAGS_privkey += $(if $(PRIVKEY),-DPRIVATE_KEY="\"$(PRIVKEY_INC)\"")
 
+# (Single-element) list of named configurations
+#
+CONFIG_LIST := $(BIN)/.config.list
+ifeq ($(wildcard $(CONFIG_LIST)),)
+CONFIG_OLD := <invalid>
+else
+CONFIG_OLD := $(shell cat $(CONFIG_LIST))
+endif
+ifneq ($(CONFIG_OLD),$(CONFIG))
+$(shell $(ECHO) "$(CONFIG)" > $(CONFIG_LIST))
+endif
+
+$(CONFIG_LIST) : $(MAKEDEPS)
+
+VERYCLEANUP += $(CONFIG_LIST)
+
+# Named configurations
+#
+ifneq ($(CONFIG),)
+ifneq ($(wildcard config/$(CONFIG)),)
+CFLAGS	+= -DCONFIG=$(CONFIG)
+endif
+CFLAGS	+= -DLOCAL_CONFIG=$(CONFIG)
+endif
+
+config/named.h : $(CONFIG_LIST)
+	$(Q)$(TOUCH) $@
+
 # These files use .incbin inline assembly to include a binary file.
 # Unfortunately ccache does not detect this dependency and caches
 # builds even when the binary file has changed.
@@ -1260,8 +1288,16 @@ CLEANUP += $(EINFO)
 #
 # Local configs
 #
-config/local/%.h :
-	$(Q)touch $@
+CONFIG_HEADERS := $(patsubst config/%,%,$(wildcard config/*.h))
+
+$(foreach HEADER,$(CONFIG_HEADERS),config/local/$(HEADER)) :
+	$(Q)$(TOUCH) $@
+
+ifneq ($(CONFIG),)
+$(foreach HEADER,$(CONFIG_HEADERS),config/local/$(CONFIG)/$(HEADER)) :
+	$(Q)$(MKDIR) -p $(dir $@)
+	$(Q)$(TOUCH) $@
+endif
 
 ###############################################################################
 #
-- 
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