kbuild: asm-generic support

[mirror_ubuntu-zesty-kernel.git] / Documentation / kbuild / makefiles.txt

diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index 86e3cd0d26a087f80024636ab98f37d6879a6339..835b64acf0b45c1f9c9085e5d8e6c3b96048e6bd 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
@@ -955,6 +957,11 @@ 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 +1216,14 @@ 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 +1280,32 @@ 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
 
@@ -1325,7 +1366,8 @@ The top Makefile exports the following variables:
        If this variable is specified, will cause modules to be stripped
        after they are installed.  If INSTALL_MOD_STRIP is '1', then the
        default option --strip-debug will be used.  Otherwise,
-       INSTALL_MOD_STRIP will used as the option(s) to the strip command.
+       INSTALL_MOD_STRIP value will be used as the option(s) to the strip
+       command.
 
 
 === 9 Makefile language