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[linux-2.6.git] / Documentation / kbuild / makefiles.txt

diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index 1075e4d..2616a58 100644 (file)
--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -6,7 +6,7 @@ This document describes the Linux kernel Makefiles.
 
        === 1 Overview
        === 2 Who does what
 
        === 1 Overview
        === 2 Who does what

-       === 3 The kbuild Makefiles
+       === 3 The kbuild files

           --- 3.1 Goal definitions
           --- 3.2 Built-in object goals - obj-y
           --- 3.3 Loadable module goals - obj-m
           --- 3.1 Goal definitions
           --- 3.2 Built-in object goals - obj-y
           --- 3.3 Loadable module goals - obj-m


@@ -101,11 +101,14 @@ These people need to know about all aspects of the kernel Makefiles.
 This document is aimed towards normal developers and arch developers.
 
 
 This document is aimed towards normal developers and arch developers.
 
 

-=== 3 The kbuild Makefiles
+=== 3 The kbuild files

 
 Most Makefiles within the kernel are kbuild Makefiles that use the
 kbuild infrastructure. This chapter introduce the syntax used in the
 kbuild makefiles.
 
 Most Makefiles within the kernel are kbuild Makefiles that use the
 kbuild infrastructure. This chapter introduce the syntax used in the
 kbuild makefiles.

+The preferred name for the kbuild files is 'Kbuild' but 'Makefile' will
+continue to be supported. All new developmen is expected to use the
+Kbuild filename.

 
 Section 3.1 "Goal definitions" is a quick intro, further chapters provide
 more details, with real examples.
 
 Section 3.1 "Goal definitions" is a quick intro, further chapters provide
 more details, with real examples.


@@ -707,15 +710,17 @@ When kbuild executes the following steps are followed (roughly):
        probe supported options:
 
                #arch/i386/Makefile
        probe supported options:
 
                #arch/i386/Makefile

-               check_gcc = $(shell if $(CC) $(1) -S -o /dev/null -xc \
-                           /dev/null\ > /dev/null 2>&1; then echo "$(1)"; \
-                           else echo "$(2)"; fi)
-               cflags-$(CONFIG_MCYRIXIII) += $(call check_gcc,\
-                                                    -march=c3,-march=i486)

 
 

-               CFLAGS += $(cflags-y)
+               ...
+               cflags-$(CONFIG_MPENTIUMII)     += $(call cc-option,\
+                                               -march=pentium2,-march=i686)
+               ...
+               # Disable unit-at-a-time mode ...
+               CFLAGS += $(call cc-option,-fno-unit-at-a-time)
+               ...
+

 
 

-       The above examples both utilise the trick that a config option expands
+       The first examples utilises the trick that a config option expands

        to 'y' when selected.
 
     CFLAGS_KERNEL      $(CC) options specific for built-in
        to 'y' when selected.
 
     CFLAGS_KERNEL      $(CC) options specific for built-in


@@ -997,6 +1002,21 @@ When kbuild executes the following steps are followed (roughly):
        option. When $(biarch) equals to y the expanded variables $(aflags-y)
        and $(cflags-y) will be assigned the values -a32 and -m32.
 
        option. When $(biarch) equals to y the expanded variables $(aflags-y)
        and $(cflags-y) will be assigned the values -a32 and -m32.
 

+    cc-option-align
+       gcc version >= 3.0 shifted type of options used to speify
+       alignment of functions, loops etc. $(cc-option-align) whrn used
+       as prefix to the align options will select the right prefix:
+       gcc < 3.00
+               cc-option-align = -malign
+       gcc >= 3.00
+               cc-option-align = -falign
+       
+       Example:
+               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.
+       

     cc-version
        cc-version return a numerical version of the $(CC) compiler version.
        The format is <major><minor> where both are two digits. So for example
     cc-version
        cc-version return a numerical version of the $(CC) compiler version.
        The format is <major><minor> where both are two digits. So for example