Documentation / kbuild / kbuild.txt
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Based on kernel version 3.3. Page generated on 2012-03-23 21:34 EST.
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 KBUILD_VERBOSE 54 -------------------------------------------------- 55 Set the kbuild verbosity. Can be assigned same values as "V=...". 56 See make help for the full list. 57 Setting "V=..." takes precedence over KBUILD_VERBOSE. 58 59 KBUILD_EXTMOD 60 -------------------------------------------------- 61 Set the directory to look for the kernel source when building external 62 modules. 63 The directory can be specified in several ways: 64 1) Use "M=..." on the command line 65 2) Environment variable KBUILD_EXTMOD 66 3) Environment variable SUBDIRS 67 The possibilities are listed in the order they take precedence. 68 Using "M=..." will always override the others. 69 70 KBUILD_OUTPUT 71 -------------------------------------------------- 72 Specify the output directory when building the kernel. 73 The output directory can also be specified using "O=...". 74 Setting "O=..." takes precedence over KBUILD_OUTPUT. 75 76 KBUILD_DEBARCH 77 -------------------------------------------------- 78 For the deb-pkg target, allows overriding the normal heuristics deployed by 79 deb-pkg. Normally deb-pkg attempts to guess the right architecture based on 80 the UTS_MACHINE variable, and on some architectures also the kernel config. 81 The value of KBUILD_DEBARCH is assumed (not checked) to be a valid Debian 82 architecture. 83 84 ARCH 85 -------------------------------------------------- 86 Set ARCH to the architecture to be built. 87 In most cases the name of the architecture is the same as the 88 directory name found in the arch/ directory. 89 But some architectures such as x86 and sparc have aliases. 90 x86: i386 for 32 bit, x86_64 for 64 bit 91 sparc: sparc for 32 bit, sparc64 for 64 bit 92 93 CROSS_COMPILE 94 -------------------------------------------------- 95 Specify an optional fixed part of the binutils filename. 96 CROSS_COMPILE can be a part of the filename or the full path. 97 98 CROSS_COMPILE is also used for ccache in some setups. 99 100 CF 101 -------------------------------------------------- 102 Additional options for sparse. 103 CF is often used on the command-line like this: 104 105 make CF=-Wbitwise C=2 106 107 INSTALL_PATH 108 -------------------------------------------------- 109 INSTALL_PATH specifies where to place the updated kernel and system map 110 images. Default is /boot, but you can set it to other values. 111 112 INSTALLKERNEL 113 -------------------------------------------------- 114 Install script called when using "make install". 115 The default name is "installkernel". 116 117 The script will be called with the following arguments: 118 $1 - kernel version 119 $2 - kernel image file 120 $3 - kernel map file 121 $4 - default install path (use root directory if blank) 122 123 The implementation of "make install" is architecture specific 124 and it may differ from the above. 125 126 INSTALLKERNEL is provided to enable the possibility to 127 specify a custom installer when cross compiling a kernel. 128 129 MODLIB 130 -------------------------------------------------- 131 Specify where to install modules. 132 The default value is: 133 134 $(INSTALL_MOD_PATH)/lib/modules/$(KERNELRELEASE) 135 136 The value can be overridden in which case the default value is ignored. 137 138 INSTALL_MOD_PATH 139 -------------------------------------------------- 140 INSTALL_MOD_PATH specifies a prefix to MODLIB for module directory 141 relocations required by build roots. This is not defined in the 142 makefile but the argument can be passed to make if needed. 143 144 INSTALL_MOD_STRIP 145 -------------------------------------------------- 146 INSTALL_MOD_STRIP, if defined, will cause modules to be 147 stripped after they are installed. If INSTALL_MOD_STRIP is '1', then 148 the default option --strip-debug will be used. Otherwise, 149 INSTALL_MOD_STRIP value will be used as the options to the strip command. 150 151 INSTALL_FW_PATH 152 -------------------------------------------------- 153 INSTALL_FW_PATH specifies where to install the firmware blobs. 154 The default value is: 155 156 $(INSTALL_MOD_PATH)/lib/firmware 157 158 The value can be overridden in which case the default value is ignored. 159 160 INSTALL_HDR_PATH 161 -------------------------------------------------- 162 INSTALL_HDR_PATH specifies where to install user space headers when 163 executing "make headers_*". 164 The default value is: 165 166 $(objtree)/usr 167 168 $(objtree) is the directory where output files are saved. 169 The output directory is often set using "O=..." on the commandline. 170 171 The value can be overridden in which case the default value is ignored. 172 173 KBUILD_MODPOST_WARN 174 -------------------------------------------------- 175 KBUILD_MODPOST_WARN can be set to avoid errors in case of undefined 176 symbols in the final module linking stage. It changes such errors 177 into warnings. 178 179 KBUILD_MODPOST_NOFINAL 180 -------------------------------------------------- 181 KBUILD_MODPOST_NOFINAL can be set to skip the final link of modules. 182 This is solely useful to speed up test compiles. 183 184 KBUILD_EXTRA_SYMBOLS 185 -------------------------------------------------- 186 For modules that use symbols from other modules. 187 See more details in modules.txt. 188 189 ALLSOURCE_ARCHS 190 -------------------------------------------------- 191 For tags/TAGS/cscope targets, you can specify more than one arch 192 to be included in the databases, separated by blank space. E.g.: 193 194 $ make ALLSOURCE_ARCHS="x86 mips arm" tags 195 196 To get all available archs you can also specify all. E.g.: 197 198 $ make ALLSOURCE_ARCHS=all tags 199 200 KBUILD_ENABLE_EXTRA_GCC_CHECKS 201 -------------------------------------------------- 202 If enabled over the make command line with "W=1", it turns on additional 203 gcc -W... options for more extensive build-time checking. 204 205 KBUILD_BUILD_TIMESTAMP 206 -------------------------------------------------- 207 Setting this to a date string overrides the timestamp used in the 208 UTS_VERSION definition (uname -v in the running kernel). The value has to 209 be a string that can be passed to date -d. The default value 210 is the output of the date command at one point during build. 211 212 KBUILD_BUILD_USER, KBUILD_BUILD_HOST 213 -------------------------------------------------- 214 These two variables allow to override the user@host string displayed during 215 boot and in /proc/version. The default value is the output of the commands 216 whoami and host, respectively.
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