kbuild: enable 'make CFLAGS=...' to add additional options to CC

[deliverable/linux.git] / Documentation / kbuild / makefiles.txt

diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index 54bbfd37f1578db630203f7449e7eeb5b65122aa..1ca535bcc8c7d3adeae372d74bdea0fc801a9198 100644 (file)
--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -294,7 +294,7 @@ more details, with real examples.
 
 
        This variable is necessary because the top Makefile owns the
-       variable $(CFLAGS) and uses it for compilation flags for the
+       variable $(KBUILD_CFLAGS) and uses it for compilation flags for the
        entire tree.
 
        $(EXTRA_AFLAGS) is a similar string for per-directory options
@@ -437,6 +437,7 @@ more details, with real examples.
        -march=pentium-mmx if supported by $(CC), otherwise -march=i586.
        The second argument to cc-option is optional, and if omitted,
        cflags-y will be assigned no value if first option is not supported.
+       Note: cc-option uses KBUILD_CFLAGS for $(CC) options
 
    cc-option-yn
        cc-option-yn is used to check if gcc supports a given option
@@ -452,6 +453,7 @@ more details, with real examples.
        option. When $(biarch) equals 'y', the expanded variables $(aflags-y)
        and $(cflags-y) will be assigned the values -a32 and -m32,
        respectively.
+       Note: cc-option-yn uses KBUILD_CFLAGS for $(CC) options
 
     cc-option-align
        gcc versions >= 3.0 changed the type of options used to specify
@@ -463,10 +465,11 @@ more details, with real examples.
                cc-option-align = -falign
 
        Example:
-               CFLAGS += $(cc-option-align)-functions=4
+               KBUILD_CFLAGS += $(cc-option-align)-functions=4
 
        In the above example, the option -falign-functions=4 is used for
        gcc >= 3.00. For gcc < 3.00, -malign-functions=4 is used.
+       Note: cc-option-align uses KBUILD_CFLAGS for $(CC) options
 
     cc-version
        cc-version returns a numerical version of the $(CC) compiler version.
@@ -825,17 +828,17 @@ When kbuild executes, the following steps are followed (roughly):
                #arch/sparc64/Makefile
                AFLAGS += -m64 -mcpu=ultrasparc
 
-    CFLAGS             $(CC) compiler flags
+    KBUILD_CFLAGS              $(CC) compiler flags
 
        Default value - see top level Makefile
        Append or modify as required per architecture.
 
-       Often, the CFLAGS variable depends on the configuration.
+       Often, the KBUILD_CFLAGS variable depends on the configuration.
 
        Example:
                #arch/i386/Makefile
                cflags-$(CONFIG_M386) += -march=i386
-               CFLAGS += $(cflags-y)
+               KBUILD_CFLAGS += $(cflags-y)
 
        Many arch Makefiles dynamically run the target C compiler to
        probe supported options:
@@ -847,7 +850,7 @@ When kbuild executes, the following steps are followed (roughly):
                                                -march=pentium2,-march=i686)
                ...
                # Disable unit-at-a-time mode ...
-               CFLAGS += $(call cc-option,-fno-unit-at-a-time)
+               KBUILD_CFLAGS += $(call cc-option,-fno-unit-at-a-time)
                ...