1 files changed, 53 insertions, 0 deletions

diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index 5d145bb443c0..47435e56c5da 100644
--- 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