summaryrefslogtreecommitdiffstats
path: root/Documentation/kbuild/kbuild.txt
blob: 51771847e816d8905fc74465f0a82c75a5ccd0d9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
Environment variables

KCPPFLAGS
--------------------------------------------------
Additional options to pass when preprocessing. The preprocessing options
will be used in all cases where kbuild do 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 assinged 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 suach as x86 and sparc has 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 specify 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 specify 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 error out in case of undefined
symbols in the final module linking stage.

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

KBUILD_EXTRA_SYMBOLS
--------------------------------------------------
For modules use symbols from another modules.
See more details in modules.txt.
OpenPOWER on IntegriCloud