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1 Output files
2
3 modules.order
4 --------------------------------------------------
5 This file records the order in which modules appear in Makefiles. This
6 is used by modprobe to deterministically resolve aliases that match
7 multiple modules.
8
9 modules.builtin
10 --------------------------------------------------
11 This file lists all modules that are built into the kernel. This is used
12 by modprobe to not fail when trying to load something builtin.
13
14
15 Environment variables
16
17 KCPPFLAGS
18 --------------------------------------------------
19 Additional options to pass when preprocessing. The preprocessing options
20 will be used in all cases where kbuild does preprocessing including
21 building C files and assembler files.
22
23 KAFLAGS
24 --------------------------------------------------
25 Additional options to the assembler (for built-in and modules).
26
27 AFLAGS_MODULE
28 --------------------------------------------------
29 Additional module specific options to use for $(AS).
30
31 AFLAGS_KERNEL
32 --------------------------------------------------
33 Additional options for $(AS) when used for assembler
34 code for code that is compiled as built-in.
35
36 KCFLAGS
37 --------------------------------------------------
38 Additional options to the C compiler (for built-in and modules).
39
40 CFLAGS_KERNEL
41 --------------------------------------------------
42 Additional options for $(CC) when used to compile
43 code that is compiled as built-in.
44
45 CFLAGS_MODULE
46 --------------------------------------------------
47 Additional module specific options to use for $(CC).
48
49 LDFLAGS_MODULE
50 --------------------------------------------------
51 Additional options used for $(LD) when linking modules.
52
53 LDFLAGS_vmlinux
54 --------------------------------------------------
55 Additional options passed to final link of vmlinux.
56
57 KBUILD_VERBOSE
58 --------------------------------------------------
59 Set the kbuild verbosity. Can be assigned same values as "V=...".
60 See make help for the full list.
61 Setting "V=..." takes precedence over KBUILD_VERBOSE.
62
63 KBUILD_EXTMOD
64 --------------------------------------------------
65 Set the directory to look for the kernel source when building external
66 modules.
67 The directory can be specified in several ways:
68 1) Use "M=..." on the command line
69 2) Environment variable KBUILD_EXTMOD
70 3) Environment variable SUBDIRS
71 The possibilities are listed in the order they take precedence.
72 Using "M=..." will always override the others.
73
74 KBUILD_OUTPUT
75 --------------------------------------------------
76 Specify the output directory when building the kernel.
77 The output directory can also be specified using "O=...".
78 Setting "O=..." takes precedence over KBUILD_OUTPUT.
79
80 KBUILD_DEBARCH
81 --------------------------------------------------
82 For the deb-pkg target, allows overriding the normal heuristics deployed by
83 deb-pkg. Normally deb-pkg attempts to guess the right architecture based on
84 the UTS_MACHINE variable, and on some architectures also the kernel config.
85 The value of KBUILD_DEBARCH is assumed (not checked) to be a valid Debian
86 architecture.
87
88 ARCH
89 --------------------------------------------------
90 Set ARCH to the architecture to be built.
91 In most cases the name of the architecture is the same as the
92 directory name found in the arch/ directory.
93 But some architectures such as x86 and sparc have aliases.
94 x86: i386 for 32 bit, x86_64 for 64 bit
95 sparc: sparc for 32 bit, sparc64 for 64 bit
96
97 CROSS_COMPILE
98 --------------------------------------------------
99 Specify an optional fixed part of the binutils filename.
100 CROSS_COMPILE can be a part of the filename or the full path.
101
102 CROSS_COMPILE is also used for ccache in some setups.
103
104 CF
105 --------------------------------------------------
106 Additional options for sparse.
107 CF is often used on the command-line like this:
108
109 make CF=-Wbitwise C=2
110
111 INSTALL_PATH
112 --------------------------------------------------
113 INSTALL_PATH specifies where to place the updated kernel and system map
114 images. Default is /boot, but you can set it to other values.
115
116 INSTALLKERNEL
117 --------------------------------------------------
118 Install script called when using "make install".
119 The default name is "installkernel".
120
121 The script will be called with the following arguments:
122 $1 - kernel version
123 $2 - kernel image file
124 $3 - kernel map file
125 $4 - default install path (use root directory if blank)
126
127 The implementation of "make install" is architecture specific
128 and it may differ from the above.
129
130 INSTALLKERNEL is provided to enable the possibility to
131 specify a custom installer when cross compiling a kernel.
132
133 MODLIB
134 --------------------------------------------------
135 Specify where to install modules.
136 The default value is:
137
138 $(INSTALL_MOD_PATH)/lib/modules/$(KERNELRELEASE)
139
140 The value can be overridden in which case the default value is ignored.
141
142 INSTALL_MOD_PATH
143 --------------------------------------------------
144 INSTALL_MOD_PATH specifies a prefix to MODLIB for module directory
145 relocations required by build roots. This is not defined in the
146 makefile but the argument can be passed to make if needed.
147
148 INSTALL_MOD_STRIP
149 --------------------------------------------------
150 INSTALL_MOD_STRIP, if defined, will cause modules to be
151 stripped after they are installed. If INSTALL_MOD_STRIP is '1', then
152 the default option --strip-debug will be used. Otherwise,
153 INSTALL_MOD_STRIP value will be used as the options to the strip command.
154
155 INSTALL_FW_PATH
156 --------------------------------------------------
157 INSTALL_FW_PATH specifies where to install the firmware blobs.
158 The default value is:
159
160 $(INSTALL_MOD_PATH)/lib/firmware
161
162 The value can be overridden in which case the default value is ignored.
163
164 INSTALL_HDR_PATH
165 --------------------------------------------------
166 INSTALL_HDR_PATH specifies where to install user space headers when
167 executing "make headers_*".
168 The default value is:
169
170 $(objtree)/usr
171
172 $(objtree) is the directory where output files are saved.
173 The output directory is often set using "O=..." on the commandline.
174
175 The value can be overridden in which case the default value is ignored.
176
177 KBUILD_MODPOST_WARN
178 --------------------------------------------------
179 KBUILD_MODPOST_WARN can be set to avoid errors in case of undefined
180 symbols in the final module linking stage. It changes such errors
181 into warnings.
182
183 KBUILD_MODPOST_NOFINAL
184 --------------------------------------------------
185 KBUILD_MODPOST_NOFINAL can be set to skip the final link of modules.
186 This is solely useful to speed up test compiles.
187
188 KBUILD_EXTRA_SYMBOLS
189 --------------------------------------------------
190 For modules that use symbols from other modules.
191 See more details in modules.txt.
192
193 ALLSOURCE_ARCHS
194 --------------------------------------------------
195 For tags/TAGS/cscope targets, you can specify more than one arch
196 to be included in the databases, separated by blank space. E.g.:
197
198 $ make ALLSOURCE_ARCHS="x86 mips arm" tags
199
200 To get all available archs you can also specify all. E.g.:
201
202 $ make ALLSOURCE_ARCHS=all tags
203
204 KBUILD_ENABLE_EXTRA_GCC_CHECKS
205 --------------------------------------------------
206 If enabled over the make command line with "W=1", it turns on additional
207 gcc -W... options for more extensive build-time checking.
208
209 KBUILD_BUILD_TIMESTAMP
210 --------------------------------------------------
211 Setting this to a date string overrides the timestamp used in the
212 UTS_VERSION definition (uname -v in the running kernel). The value has to
213 be a string that can be passed to date -d. The default value
214 is the output of the date command at one point during build.
215
216 KBUILD_BUILD_USER, KBUILD_BUILD_HOST
217 --------------------------------------------------
218 These two variables allow to override the user@host string displayed during
219 boot and in /proc/version. The default value is the output of the commands
220 whoami and host, respectively.
221
222 KBUILD_LDS
223 --------------------------------------------------
224 The linker script with full path. Assigned by the top-level Makefile.
225
226 KBUILD_VMLINUX_INIT
227 --------------------------------------------------
228 All object files for the init (first) part of vmlinux.
229 Files specified with KBUILD_VMLINUX_INIT are linked first.
230
231 KBUILD_VMLINUX_MAIN
232 --------------------------------------------------
233 All object files for the main part of vmlinux.
234 KBUILD_VMLINUX_INIT and KBUILD_VMLINUX_MAIN together specify
235 all the object files used to link vmlinux.