| 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. |
| |
| ALLSOURCE_ARCHS |
| -------------------------------------------------- |
| For tags/TAGS/cscope targets, you can specify more than one archs |
| to be included in the databases, separated by blankspace. e.g. |
| |
| $ make ALLSOURCE_ARCHS="x86 mips arm" tags |
