1Output files 2 3modules.order 4-------------------------------------------------- 5This file records the order in which modules appear in Makefiles. This 6is used by modprobe to deterministically resolve aliases that match 7multiple modules. 8 9modules.builtin 10-------------------------------------------------- 11This file lists all modules that are built into the kernel. This is used 12by modprobe to not fail when trying to load something builtin. 13 14 15Environment variables 16 17KCPPFLAGS 18-------------------------------------------------- 19Additional options to pass when preprocessing. The preprocessing options 20will be used in all cases where kbuild does preprocessing including 21building C files and assembler files. 22 23KAFLAGS 24-------------------------------------------------- 25Additional options to the assembler (for built-in and modules). 26 27AFLAGS_MODULE 28-------------------------------------------------- 29Additional module specific options to use for $(AS). 30 31AFLAGS_KERNEL 32-------------------------------------------------- 33Additional options for $(AS) when used for assembler 34code for code that is compiled as built-in. 35 36KCFLAGS 37-------------------------------------------------- 38Additional options to the C compiler (for built-in and modules). 39 40CFLAGS_KERNEL 41-------------------------------------------------- 42Additional options for $(CC) when used to compile 43code that is compiled as built-in. 44 45CFLAGS_MODULE 46-------------------------------------------------- 47Additional module specific options to use for $(CC). 48 49LDFLAGS_MODULE 50-------------------------------------------------- 51Additional options used for $(LD) when linking modules. 52 53LDFLAGS_vmlinux 54-------------------------------------------------- 55Additional options passed to final link of vmlinux. 56 57KBUILD_VERBOSE 58-------------------------------------------------- 59Set the kbuild verbosity. Can be assigned same values as "V=...". 60See make help for the full list. 61Setting "V=..." takes precedence over KBUILD_VERBOSE. 62 63KBUILD_EXTMOD 64-------------------------------------------------- 65Set the directory to look for the kernel source when building external 66modules. 67The directory can be specified in several ways: 681) Use "M=..." on the command line 692) Environment variable KBUILD_EXTMOD 703) Environment variable SUBDIRS 71The possibilities are listed in the order they take precedence. 72Using "M=..." will always override the others. 73 74KBUILD_OUTPUT 75-------------------------------------------------- 76Specify the output directory when building the kernel. 77The output directory can also be specified using "O=...". 78Setting "O=..." takes precedence over KBUILD_OUTPUT. 79 80KBUILD_DEBARCH 81-------------------------------------------------- 82For the deb-pkg target, allows overriding the normal heuristics deployed by 83deb-pkg. Normally deb-pkg attempts to guess the right architecture based on 84the UTS_MACHINE variable, and on some architectures also the kernel config. 85The value of KBUILD_DEBARCH is assumed (not checked) to be a valid Debian 86architecture. 87 88ARCH 89-------------------------------------------------- 90Set ARCH to the architecture to be built. 91In most cases the name of the architecture is the same as the 92directory name found in the arch/ directory. 93But some architectures such as x86 and sparc have aliases. 94x86: i386 for 32 bit, x86_64 for 64 bit 95sparc: sparc for 32 bit, sparc64 for 64 bit 96 97CROSS_COMPILE 98-------------------------------------------------- 99Specify an optional fixed part of the binutils filename. 100CROSS_COMPILE can be a part of the filename or the full path. 101 102CROSS_COMPILE is also used for ccache in some setups. 103 104CF 105-------------------------------------------------- 106Additional options for sparse. 107CF is often used on the command-line like this: 108 109 make CF=-Wbitwise C=2 110 111INSTALL_PATH 112-------------------------------------------------- 113INSTALL_PATH specifies where to place the updated kernel and system map 114images. Default is /boot, but you can set it to other values. 115 116INSTALLKERNEL 117-------------------------------------------------- 118Install script called when using "make install". 119The default name is "installkernel". 120 121The 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 127The implementation of "make install" is architecture specific 128and it may differ from the above. 129 130INSTALLKERNEL is provided to enable the possibility to 131specify a custom installer when cross compiling a kernel. 132 133MODLIB 134-------------------------------------------------- 135Specify where to install modules. 136The default value is: 137 138 $(INSTALL_MOD_PATH)/lib/modules/$(KERNELRELEASE) 139 140The value can be overridden in which case the default value is ignored. 141 142INSTALL_MOD_PATH 143-------------------------------------------------- 144INSTALL_MOD_PATH specifies a prefix to MODLIB for module directory 145relocations required by build roots. This is not defined in the 146makefile but the argument can be passed to make if needed. 147 148INSTALL_MOD_STRIP 149-------------------------------------------------- 150INSTALL_MOD_STRIP, if defined, will cause modules to be 151stripped after they are installed. If INSTALL_MOD_STRIP is '1', then 152the default option --strip-debug will be used. Otherwise, 153INSTALL_MOD_STRIP value will be used as the options to the strip command. 154 155INSTALL_HDR_PATH 156-------------------------------------------------- 157INSTALL_HDR_PATH specifies where to install user space headers when 158executing "make headers_*". 159The default value is: 160 161 $(objtree)/usr 162 163$(objtree) is the directory where output files are saved. 164The output directory is often set using "O=..." on the commandline. 165 166The value can be overridden in which case the default value is ignored. 167 168KBUILD_SIGN_PIN 169-------------------------------------------------- 170This variable allows a passphrase or PIN to be passed to the sign-file 171utility when signing kernel modules, if the private key requires such. 172 173KBUILD_MODPOST_WARN 174-------------------------------------------------- 175KBUILD_MODPOST_WARN can be set to avoid errors in case of undefined 176symbols in the final module linking stage. It changes such errors 177into warnings. 178 179KBUILD_MODPOST_NOFINAL 180-------------------------------------------------- 181KBUILD_MODPOST_NOFINAL can be set to skip the final link of modules. 182This is solely useful to speed up test compiles. 183 184KBUILD_EXTRA_SYMBOLS 185-------------------------------------------------- 186For modules that use symbols from other modules. 187See more details in modules.txt. 188 189ALLSOURCE_ARCHS 190-------------------------------------------------- 191For tags/TAGS/cscope targets, you can specify more than one arch 192to be included in the databases, separated by blank space. E.g.: 193 194 $ make ALLSOURCE_ARCHS="x86 mips arm" tags 195 196To get all available archs you can also specify all. E.g.: 197 198 $ make ALLSOURCE_ARCHS=all tags 199 200KBUILD_ENABLE_EXTRA_GCC_CHECKS 201-------------------------------------------------- 202If enabled over the make command line with "W=1", it turns on additional 203gcc -W... options for more extensive build-time checking. 204 205KBUILD_BUILD_TIMESTAMP 206-------------------------------------------------- 207Setting this to a date string overrides the timestamp used in the 208UTS_VERSION definition (uname -v in the running kernel). The value has to 209be a string that can be passed to date -d. The default value 210is the output of the date command at one point during build. 211 212KBUILD_BUILD_USER, KBUILD_BUILD_HOST 213-------------------------------------------------- 214These two variables allow to override the user@host string displayed during 215boot and in /proc/version. The default value is the output of the commands 216whoami and host, respectively. 217 218KBUILD_LDS 219-------------------------------------------------- 220The linker script with full path. Assigned by the top-level Makefile. 221 222KBUILD_VMLINUX_INIT 223-------------------------------------------------- 224All object files for the init (first) part of vmlinux. 225Files specified with KBUILD_VMLINUX_INIT are linked first. 226 227KBUILD_VMLINUX_MAIN 228-------------------------------------------------- 229All object files for the main part of vmlinux. 230 231KBUILD_VMLINUX_LIBS 232-------------------------------------------------- 233All .a "lib" files for vmlinux. 234KBUILD_VMLINUX_INIT, KBUILD_VMLINUX_MAIN, and KBUILD_VMLINUX_LIBS together 235specify all the object files used to link vmlinux. 236