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

Environment variables

KCPPFLAGS
--------------------------------------------------
Additional options to pass when preprocessing. The preprocessing options
will be used in all cases where kbuild does preprocessing including
building C files and assembler files.

KAFLAGS
--------------------------------------------------
Additional options to the assembler.

KCFLAGS
--------------------------------------------------
Additional options to the C compiler.

KBUILD_VERBOSE
--------------------------------------------------
Set the kbuild verbosity. Can be assigned same values as "V=...".
See make help for the full list.
Setting "V=..." takes precedence over KBUILD_VERBOSE.

KBUILD_EXTMOD
--------------------------------------------------
Set the directory to look for the kernel source when building external
modules.
The directory can be specified in several ways:
1) Use "M=..." on the command line
2) Environmnet variable KBUILD_EXTMOD
3) Environmnet variable SUBDIRS
The possibilities are listed in the order they take precedence.
Using "M=..." will always override the others.

KBUILD_OUTPUT
--------------------------------------------------
Specify the output directory when building the kernel.
The output directory can also be specificed using "O=...".
Setting "O=..." takes precedence over KBUILD_OUTPUT.

ARCH
--------------------------------------------------
Set ARCH to the architecture to be built.
In most cases the name of the architecture is the same as the
directory name found in the arch/ directory.
But some architectures such as x86 and sparc have aliases.
x86: i386 for 32 bit, x86_64 for 64 bit
sparc: sparc for 32 bit, sparc64 for 64 bit

CROSS_COMPILE
--------------------------------------------------
Specify an optional fixed part of the binutils filename.
CROSS_COMPILE can be a part of the filename or the full path.

CROSS_COMPILE is also used for ccache is some setups.

CF
--------------------------------------------------
Additional options for sparse.
CF is often used on the command-line like this:

    make CF=-Wbitwise C=2

INSTALL_PATH
--------------------------------------------------
INSTALL_PATH specifies where to place the updated kernel and system map
images. Default is /boot, but you can set it to other values.


MODLIB
--------------------------------------------------
Specify where to install modules.
The default value is:

     $(INSTALL_MOD_PATH)/lib/modules/$(KERNELRELEASE)

The value can be overridden in which case the default value is ignored.

INSTALL_MOD_PATH
--------------------------------------------------
INSTALL_MOD_PATH specifies a prefix to MODLIB for module directory
relocations required by build roots.  This is not defined in the
makefile but the argument can be passed to make if needed.

INSTALL_MOD_STRIP
--------------------------------------------------
INSTALL_MOD_STRIP, if defined, 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 options to the strip command.

INSTALL_FW_PATH
--------------------------------------------------
INSTALL_FW_PATH specifies where to install the firmware blobs.
The default value is:

    $(INSTALL_MOD_PATH)/lib/firmware

The value can be overridden in which case the default value is ignored.

INSTALL_HDR_PATH
--------------------------------------------------
INSTALL_HDR_PATH specifies where to install user space headers when
executing "make headers_*".
The default value is:

    $(objtree)/usr

$(objtree) is the directory where output files are saved.
The output directory is often set using "O=..." on the commandline.

The value can be overridden in which case the default value is ignored.

KBUILD_MODPOST_WARN
--------------------------------------------------
KBUILD_MODPOST_WARN can be set to avoid errors in case of undefined
symbols in the final module linking stage. It changes such errors
into warnings.

KBUILD_MODPOST_NOFINAL
--------------------------------------------------
KBUILD_MODPOST_NOFINAL can be set to skip the final link of modules.
This is solely useful to speed up test compiles.

KBUILD_EXTRA_SYMBOLS
--------------------------------------------------
For modules that use symbols from other modules.
See more details in modules.txt.

ALLSOURCE_ARCHS
--------------------------------------------------
For tags/TAGS/cscope targets, you can specify more than one arch
to be included in the databases, separated by blank space. E.g.:

    $ make ALLSOURCE_ARCHS="x86 mips arm" tags
Commit	Line	Data
acc08b51 SR	1	Environment variables
	2
	3	KCPPFLAGS
	4	--------------------------------------------------
	5	Additional options to pass when preprocessing. The preprocessing options
df291fa9	6	will be used in all cases where kbuild does preprocessing including
acc08b51 SR	7	building C files and assembler files.
	8
	9	KAFLAGS
	10	--------------------------------------------------
	11	Additional options to the assembler.
	12
	13	KCFLAGS
	14	--------------------------------------------------
	15	Additional options to the C compiler.
	16
	17	KBUILD_VERBOSE
	18	--------------------------------------------------
df291fa9	19	Set the kbuild verbosity. Can be assigned same values as "V=...".
acc08b51 SR	20	See make help for the full list.
	21	Setting "V=..." takes precedence over KBUILD_VERBOSE.
	22
	23	KBUILD_EXTMOD
	24	--------------------------------------------------
	25	Set the directory to look for the kernel source when building external
	26	modules.
	27	The directory can be specified in several ways:
	28	1) Use "M=..." on the command line
	29	2) Environmnet variable KBUILD_EXTMOD
	30	3) Environmnet variable SUBDIRS
	31	The possibilities are listed in the order they take precedence.
	32	Using "M=..." will always override the others.
	33
	34	KBUILD_OUTPUT
	35	--------------------------------------------------
	36	Specify the output directory when building the kernel.
	37	The output directory can also be specificed using "O=...".
df291fa9	38	Setting "O=..." takes precedence over KBUILD_OUTPUT.
acc08b51 SR	39
	40	ARCH
	41	--------------------------------------------------
	42	Set ARCH to the architecture to be built.
	43	In most cases the name of the architecture is the same as the
	44	directory name found in the arch/ directory.
df291fa9	45	But some architectures such as x86 and sparc have aliases.
acc08b51 SR	46	x86: i386 for 32 bit, x86_64 for 64 bit
	47	sparc: sparc for 32 bit, sparc64 for 64 bit
	48
	49	CROSS_COMPILE
	50	--------------------------------------------------
	51	Specify an optional fixed part of the binutils filename.
	52	CROSS_COMPILE can be a part of the filename or the full path.
	53
	54	CROSS_COMPILE is also used for ccache is some setups.
	55
	56	CF
	57	--------------------------------------------------
	58	Additional options for sparse.
	59	CF is often used on the command-line like this:
	60
	61	make CF=-Wbitwise C=2
	62
	63	INSTALL_PATH
	64	--------------------------------------------------
	65	INSTALL_PATH specifies where to place the updated kernel and system map
df291fa9	66	images. Default is /boot, but you can set it to other values.
acc08b51 SR	67
	68
	69	MODLIB
	70	--------------------------------------------------
	71	Specify where to install modules.
	72	The default value is:
	73
	74	$(INSTALL_MOD_PATH)/lib/modules/$(KERNELRELEASE)
	75
	76	The value can be overridden in which case the default value is ignored.
	77
	78	INSTALL_MOD_PATH
	79	--------------------------------------------------
	80	INSTALL_MOD_PATH specifies a prefix to MODLIB for module directory
	81	relocations required by build roots. This is not defined in the
	82	makefile but the argument can be passed to make if needed.
	83
	84	INSTALL_MOD_STRIP
	85	--------------------------------------------------
	86	INSTALL_MOD_STRIP, if defined, will cause modules to be
	87	stripped after they are installed. If INSTALL_MOD_STRIP is '1', then
	88	the default option --strip-debug will be used. Otherwise,
	89	INSTALL_MOD_STRIP will used as the options to the strip command.
	90
	91	INSTALL_FW_PATH
	92	--------------------------------------------------
df291fa9	93	INSTALL_FW_PATH specifies where to install the firmware blobs.
acc08b51 SR	94	The default value is:
	95
	96	$(INSTALL_MOD_PATH)/lib/firmware
	97
	98	The value can be overridden in which case the default value is ignored.
	99
	100	INSTALL_HDR_PATH
	101	--------------------------------------------------
df291fa9	102	INSTALL_HDR_PATH specifies where to install user space headers when
acc08b51 SR	103	executing "make headers_*".
	104	The default value is:
	105
	106	$(objtree)/usr
	107
	108	$(objtree) is the directory where output files are saved.
	109	The output directory is often set using "O=..." on the commandline.
	110
	111	The value can be overridden in which case the default value is ignored.
	112
	113	KBUILD_MODPOST_WARN
	114	--------------------------------------------------
df291fa9 RD	115	KBUILD_MODPOST_WARN can be set to avoid errors in case of undefined
	116	symbols in the final module linking stage. It changes such errors
	117	into warnings.
acc08b51	118
df291fa9	119	KBUILD_MODPOST_NOFINAL
acc08b51 SR	120	--------------------------------------------------
acc08b51 SR	121	KBUILD_MODPOST_NOFINAL can be set to skip the final link of modules.
df291fa9	122	This is solely useful to speed up test compiles.
acc08b51 SR	123
	124	KBUILD_EXTRA_SYMBOLS
	125	--------------------------------------------------
df291fa9	126	For modules that use symbols from other modules.
acc08b51	127	See more details in modules.txt.
4f628248 JS	128
	129	ALLSOURCE_ARCHS
	130	--------------------------------------------------
df291fa9 RD	131	For tags/TAGS/cscope targets, you can specify more than one arch
df291fa9 RD	132	to be included in the databases, separated by blank space. E.g.:
4f628248 JS	133
4f628248 JS	134	$ make ALLSOURCE_ARCHS="x86 mips arm" tags