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-rw-r--r--Documentation/kbuild/kbuild.txt21
-rw-r--r--Documentation/kbuild/makefiles.txt53
2 files changed, 70 insertions, 4 deletions
diff --git a/Documentation/kbuild/kbuild.txt b/Documentation/kbuild/kbuild.txt
index f1431d099fce..68e32bb6bd80 100644
--- a/Documentation/kbuild/kbuild.txt
+++ b/Documentation/kbuild/kbuild.txt
@@ -26,11 +26,11 @@ Additional options to the assembler (for built-in and modules).
AFLAGS_MODULE
--------------------------------------------------
-Addtional module specific options to use for $(AS).
+Additional module specific options to use for $(AS).
AFLAGS_KERNEL
--------------------------------------------------
-Addtional options for $(AS) when used for assembler
+Additional options for $(AS) when used for assembler
code for code that is compiled as built-in.
KCFLAGS
@@ -39,12 +39,12 @@ Additional options to the C compiler (for built-in and modules).
CFLAGS_KERNEL
--------------------------------------------------
-Addtional options for $(CC) when used to compile
+Additional options for $(CC) when used to compile
code that is compiled as built-in.
CFLAGS_MODULE
--------------------------------------------------
-Addtional module specific options to use for $(CC).
+Additional module specific options to use for $(CC).
LDFLAGS_MODULE
--------------------------------------------------
@@ -201,3 +201,16 @@ KBUILD_ENABLE_EXTRA_GCC_CHECKS
--------------------------------------------------
If enabled over the make command line with "W=1", it turns on additional
gcc -W... options for more extensive build-time checking.
+
+KBUILD_BUILD_TIMESTAMP
+--------------------------------------------------
+Setting this to a date string overrides the timestamp used in the
+UTS_VERSION definition (uname -v in the running kernel). The value has to
+be a string that can be passed to date -d. The default value
+is the output of the date command at one point during build.
+
+KBUILD_BUILD_USER, KBUILD_BUILD_HOST
+--------------------------------------------------
+These two variables allow to override the user@host string displayed during
+boot and in /proc/version. The default value is the output of the commands
+whoami and host, respectively.
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