Merge git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input

[linux-2.6] / Documentation / kbuild / modules.txt

diff --git a/Documentation/kbuild/modules.txt b/Documentation/kbuild/modules.txt
index c91caf7eb3036624e88d5e6c37fefb7aaf95f167..7e77f93634ea507569e3554434fe7978767d7fba 100644 (file)
--- a/Documentation/kbuild/modules.txt
+++ b/Documentation/kbuild/modules.txt
@@ -18,6 +18,7 @@ In this document you will find information about:
        === 5. Include files
           --- 5.1 How to include files from the kernel include dir
           --- 5.2 External modules using an include/ dir
+          --- 5.3 External modules using several directories
        === 6. Module installation
           --- 6.1 INSTALL_MOD_PATH
           --- 6.2 INSTALL_MOD_DIR
@@ -38,7 +39,7 @@ included in the kernel tree.
 What is covered within this file is mainly information to authors
 of modules. The author of an external modules should supply
 a makefile that hides most of the complexity so one only has to type
-'make' to buld the module. A complete example will be present in
+'make' to build the module. A complete example will be present in
 chapter ¤. Creating a kbuild file for an external module".
 
 
@@ -69,7 +70,7 @@ when building an external module.
 
 --- 2.2 Available targets
 
-       $KDIR refers to path to kernel source top-level directory
+       $KDIR refers to the path to the kernel source top-level directory
 
        make -C $KDIR M=`pwd`
                Will build the module(s) located in current directory.
@@ -87,11 +88,11 @@ when building an external module.
        make -C $KDIR M=$PWD modules_install
                Install the external module(s).
                Installation default is in /lib/modules/<kernel-version>/extra,
-               but may be prefixed with INSTALL_MOD_PATH - see separate chater.
+               but may be prefixed with INSTALL_MOD_PATH - see separate chapter.
 
        make -C $KDIR M=$PWD clean
                Remove all generated files for the module - the kernel
-               source directory is not moddified.
+               source directory is not modified.
 
        make -C $KDIR M=`pwd` help
                help will list the available target when building external
@@ -99,7 +100,7 @@ when building an external module.
 
 --- 2.3 Available options:
 
-       $KDIR refer to path to kernel src
+       $KDIR refers to the path to the kernel source top-level directory
 
        make -C $KDIR
                Used to specify where to find the kernel source.
@@ -206,11 +207,11 @@ following files:
 
                KERNELDIR := /lib/modules/`uname -r`/build
                all::
-                       $(MAKE) -C $KERNELDIR M=`pwd` $@
+                       $(MAKE) -C $(KERNELDIR) M=`pwd` $@
 
                # Module specific targets
                genbin:
-                       echo "X" > 8123_bini.o_shipped
+                       echo "X" > 8123_bin.o_shipped
 
                endif
 
@@ -341,13 +342,52 @@ directory and therefore needs to deal with this in their kbuild file.
                EXTRA_CFLAGS := -Iinclude
                8123-y := 8123_if.o 8123_pci.o 8123_bin.o
 
-       Note that in the assingment there is no space between -I and the path.
-       This is a kbuild limitation and no space must be present.
-
+       Note that in the assignment there is no space between -I and the path.
+       This is a kbuild limitation:  there must be no space present.
+
+--- 5.3 External modules using several directories
+
+       If an external module does not follow the usual kernel style but
+       decide to spread files over several directories then kbuild can
+       support this too.
+
+       Consider the following example:
+       
+       |
+       +- src/complex_main.c
+       |   +- hal/hardwareif.c
+       |   +- hal/include/hardwareif.h
+       +- include/complex.h
+       
+       To build a single module named complex.ko we then need the following
+       kbuild file:
+
+       Kbuild:
+               obj-m := complex.o
+               complex-y := src/complex_main.o
+               complex-y += src/hal/hardwareif.o
+
+               EXTRA_CFLAGS := -I$(src)/include
+               EXTRA_CFLAGS += -I$(src)src/hal/include
+
+
+       kbuild knows how to handle .o files located in another directory -
+       although this is NOT reccommended practice. The syntax is to specify
+       the directory relative to the directory where the Kbuild file is
+       located.
+
+       To find the .h files we have to explicitly tell kbuild where to look
+       for the .h files. When kbuild executes current directory is always
+       the root of the kernel tree (argument to -C) and therefore we have to
+       tell kbuild how to find the .h files using absolute paths.
+       $(src) will specify the absolute path to the directory where the
+       Kbuild file are located when being build as an external module.
+       Therefore -I$(src)/ is used to point out the directory of the Kbuild
+       file and any additional path are just appended.
 
 === 6. Module installation
 
-Modules which are included in the kernel is installed in the directory:
+Modules which are included in the kernel are installed in the directory:
 
        /lib/modules/$(KERNELRELEASE)/kernel
 
@@ -365,7 +405,7 @@ External modules are installed in the directory:
                => Install dir: /frodo/lib/modules/$(KERNELRELEASE)/kernel
 
        INSTALL_MOD_PATH may be set as an ordinary shell variable or as in the
-       example above be specified on the commandline when calling make.
+       example above be specified on the command line when calling make.
        INSTALL_MOD_PATH has effect both when installing modules included in
        the kernel as well as when installing external modules.
 
@@ -384,7 +424,7 @@ External modules are installed in the directory:
 
 === 7. Module versioning
 
-Module versioning are enabled by the CONFIG_MODVERSIONS tag.
+Module versioning is enabled by the CONFIG_MODVERSIONS tag.
 
 Module versioning is used as a simple ABI consistency check. The Module
 versioning creates a CRC value of the full prototype for an exported symbol and