1 ======
2 Kbuild
3 ======
4
5
6 Output files
7 ============
8
9 modules.order
10 -------------
11 This file records the order in which modules a
12 is used by modprobe to deterministically resol
13 multiple modules.
14
15 modules.builtin
16 ---------------
17 This file lists all modules that are built int
18 by modprobe to not fail when trying to load so
19
20 modules.builtin.modinfo
21 -----------------------
22 This file contains modinfo from all modules th
23 Unlike modinfo of a separate module, all field
24
25 modules.builtin.ranges
26 ----------------------
27 This file contains address offset ranges (per
28 that are built into the kernel. Together with
29 to associate module names with symbols.
30
31 Environment variables
32 =====================
33
34 KCPPFLAGS
35 ---------
36 Additional options to pass when preprocessing.
37 will be used in all cases where kbuild does pr
38 building C files and assembler files.
39
40 KAFLAGS
41 -------
42 Additional options to the assembler (for built
43
44 AFLAGS_MODULE
45 -------------
46 Additional assembler options for modules.
47
48 AFLAGS_KERNEL
49 -------------
50 Additional assembler options for built-in.
51
52 KCFLAGS
53 -------
54 Additional options to the C compiler (for buil
55
56 KRUSTFLAGS
57 ----------
58 Additional options to the Rust compiler (for b
59
60 CFLAGS_KERNEL
61 -------------
62 Additional options for $(CC) when used to comp
63 code that is compiled as built-in.
64
65 CFLAGS_MODULE
66 -------------
67 Additional module specific options to use for
68
69 RUSTFLAGS_KERNEL
70 ----------------
71 Additional options for $(RUSTC) when used to c
72 code that is compiled as built-in.
73
74 RUSTFLAGS_MODULE
75 ----------------
76 Additional module specific options to use for
77
78 LDFLAGS_MODULE
79 --------------
80 Additional options used for $(LD) when linking
81
82 HOSTCFLAGS
83 ----------
84 Additional flags to be passed to $(HOSTCC) whe
85
86 HOSTCXXFLAGS
87 ------------
88 Additional flags to be passed to $(HOSTCXX) wh
89
90 HOSTRUSTFLAGS
91 -------------
92 Additional flags to be passed to $(HOSTRUSTC)
93
94 HOSTLDFLAGS
95 -----------
96 Additional flags to be passed when linking hos
97
98 HOSTLDLIBS
99 ----------
100 Additional libraries to link against when buil
101
102 .. _userkbuildflags:
103
104 USERCFLAGS
105 ----------
106 Additional options used for $(CC) when compili
107
108 USERLDFLAGS
109 -----------
110 Additional options used for $(LD) when linking
111 with CC, so $(USERLDFLAGS) should include "-Wl
112
113 KBUILD_KCONFIG
114 --------------
115 Set the top-level Kconfig file to the value of
116 variable. The default name is "Kconfig".
117
118 KBUILD_VERBOSE
119 --------------
120 Set the kbuild verbosity. Can be assigned same
121
122 See make help for the full list.
123
124 Setting "V=..." takes precedence over KBUILD_V
125
126 KBUILD_EXTMOD
127 -------------
128 Set the directory to look for the kernel sourc
129 modules.
130
131 Setting "M=..." takes precedence over KBUILD_E
132
133 KBUILD_OUTPUT
134 -------------
135 Specify the output directory when building the
136
137 This variable can also be used to point to the
138 building external modules against a pre-built
139 directory. Please note that this does NOT spec
140 external modules themselves.
141
142 The output directory can also be specified usi
143
144 Setting "O=..." takes precedence over KBUILD_O
145
146 KBUILD_EXTRA_WARN
147 -----------------
148 Specify the extra build checks. The same value
149 W=... from the command line.
150
151 See `make help` for the list of the supported
152
153 Setting "W=..." takes precedence over KBUILD_E
154
155 KBUILD_DEBARCH
156 --------------
157 For the deb-pkg target, allows overriding the
158 deb-pkg. Normally deb-pkg attempts to guess th
159 the UTS_MACHINE variable, and on some architec
160 The value of KBUILD_DEBARCH is assumed (not ch
161 architecture.
162
163 KDOCFLAGS
164 ---------
165 Specify extra (warning/error) flags for kernel
166 see scripts/kernel-doc for which flags are sup
167 (currently) apply to documentation builds.
168
169 ARCH
170 ----
171 Set ARCH to the architecture to be built.
172
173 In most cases the name of the architecture is
174 directory name found in the arch/ directory.
175
176 But some architectures such as x86 and sparc h
177
178 - x86: i386 for 32 bit, x86_64 for 64 bit
179 - parisc: parisc64 for 64 bit
180 - sparc: sparc32 for 32 bit, sparc64 for 64 bi
181
182 CROSS_COMPILE
183 -------------
184 Specify an optional fixed part of the binutils
185 CROSS_COMPILE can be a part of the filename or
186
187 CROSS_COMPILE is also used for ccache in some
188
189 CF
190 --
191 Additional options for sparse.
192
193 CF is often used on the command-line like this
194
195 make CF=-Wbitwise C=2
196
197 INSTALL_PATH
198 ------------
199 INSTALL_PATH specifies where to place the upda
200 images. Default is /boot, but you can set it t
201
202 INSTALLKERNEL
203 -------------
204 Install script called when using "make install
205 The default name is "installkernel".
206
207 The script will be called with the following a
208
209 - $1 - kernel version
210 - $2 - kernel image file
211 - $3 - kernel map file
212 - $4 - default install path (use root direc
213
214 The implementation of "make install" is archit
215 and it may differ from the above.
216
217 INSTALLKERNEL is provided to enable the possib
218 specify a custom installer when cross compilin
219
220 MODLIB
221 ------
222 Specify where to install modules.
223 The default value is::
224
225 $(INSTALL_MOD_PATH)/lib/modules/$(KERNELR
226
227 The value can be overridden in which case the
228
229 INSTALL_MOD_PATH
230 ----------------
231 INSTALL_MOD_PATH specifies a prefix to MODLIB
232 relocations required by build roots. This is
233 makefile but the argument can be passed to mak
234
235 INSTALL_MOD_STRIP
236 -----------------
237 INSTALL_MOD_STRIP, if defined, will cause modu
238 stripped after they are installed. If INSTALL
239 the default option --strip-debug will be used.
240 INSTALL_MOD_STRIP value will be used as the op
241
242 INSTALL_HDR_PATH
243 ----------------
244 INSTALL_HDR_PATH specifies where to install us
245 executing "make headers_*".
246
247 The default value is::
248
249 $(objtree)/usr
250
251 $(objtree) is the directory where output files
252 The output directory is often set using "O=...
253
254 The value can be overridden in which case the
255
256 INSTALL_DTBS_PATH
257 -----------------
258 INSTALL_DTBS_PATH specifies where to install d
259 relocations required by build roots. This is
260 makefile but the argument can be passed to mak
261
262 KBUILD_ABS_SRCTREE
263 ----------------------------------------------
264 Kbuild uses a relative path to point to the tr
265 when building in the source tree, the source t
266
267 Setting this flag requests Kbuild to use absol
268 There are some useful cases to do so, like whe
269 absolute path entries etc.
270
271 KBUILD_SIGN_PIN
272 ---------------
273 This variable allows a passphrase or PIN to be
274 utility when signing kernel modules, if the pr
275
276 KBUILD_MODPOST_WARN
277 -------------------
278 KBUILD_MODPOST_WARN can be set to avoid errors
279 symbols in the final module linking stage. It
280 into warnings.
281
282 KBUILD_MODPOST_NOFINAL
283 ----------------------
284 KBUILD_MODPOST_NOFINAL can be set to skip the
285 This is solely useful to speed up test compile
286
287 KBUILD_EXTRA_SYMBOLS
288 --------------------
289 For modules that use symbols from other module
290 See more details in modules.rst.
291
292 ALLSOURCE_ARCHS
293 ---------------
294 For tags/TAGS/cscope targets, you can specify
295 to be included in the databases, separated by
296
297 $ make ALLSOURCE_ARCHS="x86 mips arm" tags
298
299 To get all available archs you can also specif
300
301 $ make ALLSOURCE_ARCHS=all tags
302
303 IGNORE_DIRS
304 -----------
305 For tags/TAGS/cscope targets, you can choose w
306 be included in the databases, separated by bla
307
308 $ make IGNORE_DIRS="drivers/gpu/drm/radeon
309
310 KBUILD_BUILD_TIMESTAMP
311 ----------------------
312 Setting this to a date string overrides the ti
313 UTS_VERSION definition (uname -v in the runnin
314 be a string that can be passed to date -d. The
315 is the output of the date command at one point
316
317 KBUILD_BUILD_USER, KBUILD_BUILD_HOST
318 ------------------------------------
319 These two variables allow to override the user
320 boot and in /proc/version. The default value i
321 whoami and host, respectively.
322
323 LLVM
324 ----
325 If this variable is set to 1, Kbuild will use
326 of GCC and GNU binutils to build the kernel.
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