X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=Documentation%2Fkbuild%2Fmakefiles.txt;h=7a7753321a263f62c2a00c9d0e348716e701ac2c;hb=3b470ac43fcd9848fa65e58e54875ad75be61cec;hp=f4779cd1542fd5ffadcfb6a5075695d4bcc7b44f;hpb=222d394d30e74bb7a2a65029fcea68107b0d0eb6;p=linux-2.6

diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index f4779cd154..7a7753321a 100644
--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -276,40 +276,39 @@ more details, with real examples.
 
 --- 3.7 Compilation flags
 
-    EXTRA_CFLAGS, EXTRA_AFLAGS, EXTRA_LDFLAGS
+    ccflags-y, asflags-y and ldflags-y
+	The three flags listed above applies only to the kbuild makefile
+	where they are assigned. They are used for all the normal
+	cc, as and ld invocation happenign during a recursive build.
+	Note: Flags with the same behaviour were previously named:
+	EXTRA_CFLAGS, EXTRA_AFLAGS and EXTRA_LDFLAGS.
+	They are yet supported but their use are deprecated.
 
-	All the EXTRA_ variables apply only to the kbuild makefile
-	where they are assigned. The EXTRA_ variables apply to all
-	commands executed in the kbuild makefile.
-
-	$(EXTRA_CFLAGS) specifies options for compiling C files with
-	$(CC).
+	ccflags-y specifies options for compiling C files with $(CC).
 
 	Example:
 		# drivers/sound/emu10k1/Makefile
-		EXTRA_CFLAGS += -I$(obj)
-		ifdef DEBUG
-		    EXTRA_CFLAGS += -DEMU10K1_DEBUG
-		endif
+		ccflags-y += -I$(obj)
+		ccflags-$(DEBUG) += -DEMU10K1_DEBUG
 
 
 	This variable is necessary because the top Makefile owns the
 	variable $(KBUILD_CFLAGS) and uses it for compilation flags for the
 	entire tree.
 
-	$(EXTRA_AFLAGS) is a similar string for per-directory options
+	asflags-y is a similar string for per-directory options
 	when compiling assembly language source.
 
 	Example:
 		#arch/x86_64/kernel/Makefile
-		EXTRA_AFLAGS := -traditional
+		asflags-y := -traditional
 
 
-	$(EXTRA_LDFLAGS) is a string for per-directory options to $(LD).
+	ldflags-y is a string for per-directory options to $(LD).
 
 	Example:
 		#arch/m68k/fpsp040/Makefile
-		EXTRA_LDFLAGS := -x
+		ldflags-y := -x
 
     CFLAGS_$@, AFLAGS_$@
 
@@ -495,9 +494,9 @@ more details, with real examples.
 
 	Example:
 		#fs/reiserfs/Makefile
-		EXTRA_CFLAGS := $(call cc-ifversion, -lt, 0402, -O1)
+		ccflags-y := $(call cc-ifversion, -lt, 0402, -O1)
 
-	In this example, EXTRA_CFLAGS will be assigned the value -O1 if the
+	In this example, ccflags-y will be assigned the value -O1 if the
 	$(CC) version is less than 4.2.
 	cc-ifversion takes all the shell operators:
 	-eq, -ne, -lt, -le, -gt, and -ge
@@ -519,6 +518,28 @@ more details, with real examples.
 	In this example for a specific GCC version the build will error out explaining
 	to the user why it stops.
 
+    cc-cross-prefix
+	cc-cross-prefix is used to check if there exists a $(CC) in path with
+	one of the listed prefixes. The first prefix where there exist a
+	prefix$(CC) in the PATH is returned - and if no prefix$(CC) is found
+	then nothing is returned.
+	Additional prefixes are separated by a single space in the
+	call of cc-cross-prefix.
+	This functionality is useful for architecture Makefiles that try
+	to set CROSS_COMPILE to well-known values but may have several
+	values to select between.
+	It is recommended only to try to set CROSS_COMPILE if it is a cross
+	build (host arch is different from target arch). And if CROSS_COMPILE
+	is already set then leave it with the old value.
+
+	Example:
+		#arch/m68k/Makefile
+		ifneq ($(SUBARCH),$(ARCH))
+		        ifeq ($(CROSS_COMPILE),)
+		               CROSS_COMPILE := $(call cc-cross-prefix, m68k-linux-gnu-)
+			endif
+		endif
+
 === 4 Host Program support
 
 Kbuild supports building executables on the host for use during the
@@ -783,7 +804,7 @@ When kbuild executes, the following steps are followed (roughly):
 	Example:
 		#arch/s390/Makefile
 		LDFLAGS         := -m elf_s390
-	Note: EXTRA_LDFLAGS can be used to further customise
+	Note: ldflags-y can be used to further customise
 	the flags used. See chapter 3.7.
 
     LDFLAGS_MODULE	Options for $(LD) when linking modules
@@ -1099,8 +1120,8 @@ When kbuild executes, the following steps are followed (roughly):
 	specified options when building the target vmlinux.lds.
 
 	When building the *.lds target, kbuild uses the variables:
-	CPPFLAGS	: Set in top-level Makefile
-	EXTRA_CPPFLAGS	: May be set in the kbuild makefile
+	KBUILD_CPPFLAGS	: Set in top-level Makefile
+	cppflags-y	: May be set in the kbuild makefile
 	CPPFLAGS_$(@F)  : Target specific flags.
 	                  Note that the full filename is used in this
 	                  assignment.