Merge branch 'for-3.0' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound...

[pandora-kernel.git] / Documentation / kbuild / makefiles.txt

diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index 5d145bb..47435e5 100644 (file)
--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -40,11 +40,13 @@ This document describes the Linux kernel Makefiles.
           --- 6.6 Commands useful for building a boot image
           --- 6.7 Custom kbuild commands
           --- 6.8 Preprocessing linker scripts
+          --- 6.9 Generic header files
 
        === 7 Kbuild syntax for exported headers
                --- 7.1 header-y
                --- 7.2 objhdr-y
                --- 7.3 destination-y
+               --- 7.4 generic-y
 
        === 8 Kbuild Variables
        === 9 Makefile language
@@ -499,6 +501,18 @@ more details, with real examples.
        gcc >= 3.00. For gcc < 3.00, -malign-functions=4 is used.
        Note: cc-option-align uses KBUILD_CFLAGS for $(CC) options
 
+    cc-disable-warning
+       cc-disable-warning checks if gcc supports a given warning and returns
+       the commandline switch to disable it. This special function is needed,
+       because gcc 4.4 and later accept any unknown -Wno-* option and only
+       warn about it if there is another warning in the source file.
+
+       Example:
+               KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)
+
+       In the above example, -Wno-unused-but-set-variable will be added to
+       KBUILD_CFLAGS only if gcc really accepts it.
+
     cc-version
        cc-version returns a numerical version of the $(CC) compiler version.
        The format is <major><minor> where both are two digits. So for example
@@ -955,6 +969,11 @@ When kbuild executes, the following steps are followed (roughly):
        used when linking modules. This is often a linker script.
        From commandline LDFLAGS_MODULE shall be used (see kbuild.txt).
 
+    KBUILD_ARFLAGS   Options for $(AR) when creating archives
+
+       $(KBUILD_ARFLAGS) set by the top level Makefile to "D" (deterministic
+       mode) if this option is supported by $(AR).
+
 --- 6.2 Add prerequisites to archprepare:
 
        The archprepare: rule is used to list prerequisites that need to be
@@ -1209,6 +1228,14 @@ When kbuild executes, the following steps are followed (roughly):
        The kbuild infrastructure for *lds file are used in several
        architecture-specific files.
 
+--- 6.9 Generic header files
+
+       The directory include/asm-generic contains the header files
+       that may be shared between individual architectures.
+       The recommended approach how to use a generic header file is
+       to list the file in the Kbuild file.
+       See "7.4 generic-y" for further info on syntax etc.
+
 === 7 Kbuild syntax for exported headers
 
 The kernel include a set of headers that is exported to userspace.
@@ -1265,6 +1292,32 @@ See subsequent chapter for the syntax of the Kbuild file.
        In the example above all exported headers in the Kbuild file
        will be located in the directory "include/linux" when exported.
 
+       --- 7.4 generic-y
+
+       If an architecture uses a verbatim copy of a header from
+       include/asm-generic then this is listed in the file
+       arch/$(ARCH)/include/asm/Kbuild like this:
+
+               Example:
+                       #arch/x86/include/asm/Kbuild
+                       generic-y += termios.h
+                       generic-y += rtc.h
+
+       During the prepare phase of the build a wrapper include
+       file is generated in the directory:
+
+               arch/$(ARCH)/include/generated/asm
+
+       When a header is exported where the architecture uses
+       the generic header a similar wrapper is generated as part
+       of the set of exported headers in the directory:
+
+               usr/include/asm
+
+       The generated wrapper will in both cases look like the following:
+
+               Example: termios.h
+                       #include <asm-generic/termios.h>
 
 === 8 Kbuild Variables