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Diffstat (limited to 'Documentation/kbuild/kbuild.txt')
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diff --git a/Documentation/kbuild/kbuild.txt b/Documentation/kbuild/kbuild.txt new file mode 100644 index 00000000..6466704d --- /dev/null +++ b/Documentation/kbuild/kbuild.txt @@ -0,0 +1,235 @@ +Output files + +modules.order +-------------------------------------------------- +This file records the order in which modules appear in Makefiles. This +is used by modprobe to deterministically resolve aliases that match +multiple modules. + +modules.builtin +-------------------------------------------------- +This file lists all modules that are built into the kernel. This is used +by modprobe to not fail when trying to load something builtin. + + +Environment variables + +KCPPFLAGS +-------------------------------------------------- +Additional options to pass when preprocessing. The preprocessing options +will be used in all cases where kbuild does preprocessing including +building C files and assembler files. + +KAFLAGS +-------------------------------------------------- +Additional options to the assembler (for built-in and modules). + +AFLAGS_MODULE +-------------------------------------------------- +Additional module specific options to use for $(AS). + +AFLAGS_KERNEL +-------------------------------------------------- +Additional options for $(AS) when used for assembler +code for code that is compiled as built-in. + +KCFLAGS +-------------------------------------------------- +Additional options to the C compiler (for built-in and modules). + +CFLAGS_KERNEL +-------------------------------------------------- +Additional options for $(CC) when used to compile +code that is compiled as built-in. + +CFLAGS_MODULE +-------------------------------------------------- +Additional module specific options to use for $(CC). + +LDFLAGS_MODULE +-------------------------------------------------- +Additional options used for $(LD) when linking modules. + +LDFLAGS_vmlinux +-------------------------------------------------- +Additional options passed to final link of vmlinux. + +KBUILD_VERBOSE +-------------------------------------------------- +Set the kbuild verbosity. Can be assigned 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) Environment variable KBUILD_EXTMOD +3) Environment 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 specified using "O=...". +Setting "O=..." takes precedence over KBUILD_OUTPUT. + +KBUILD_DEBARCH +-------------------------------------------------- +For the deb-pkg target, allows overriding the normal heuristics deployed by +deb-pkg. Normally deb-pkg attempts to guess the right architecture based on +the UTS_MACHINE variable, and on some architectures also the kernel config. +The value of KBUILD_DEBARCH is assumed (not checked) to be a valid Debian +architecture. + +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 such as x86 and sparc have 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 in 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. + +INSTALLKERNEL +-------------------------------------------------- +Install script called when using "make install". +The default name is "installkernel". + +The script will be called with the following arguments: + $1 - kernel version + $2 - kernel image file + $3 - kernel map file + $4 - default install path (use root directory if blank) + +The implementation of "make install" is architecture specific +and it may differ from the above. + +INSTALLKERNEL is provided to enable the possibility to +specify a custom installer when cross compiling a kernel. + +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 value will be used as the options to the strip command. + +INSTALL_FW_PATH +-------------------------------------------------- +INSTALL_FW_PATH specifies 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 specifies 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 errors in case of undefined +symbols in the final module linking stage. It changes such errors +into warnings. + +KBUILD_MODPOST_NOFINAL +-------------------------------------------------- +KBUILD_MODPOST_NOFINAL can be set to skip the final link of modules. +This is solely useful to speed up test compiles. + +KBUILD_EXTRA_SYMBOLS +-------------------------------------------------- +For modules that use symbols from other modules. +See more details in modules.txt. + +ALLSOURCE_ARCHS +-------------------------------------------------- +For tags/TAGS/cscope targets, you can specify more than one arch +to be included in the databases, separated by blank space. E.g.: + + $ make ALLSOURCE_ARCHS="x86 mips arm" tags + +To get all available archs you can also specify all. E.g.: + + $ make ALLSOURCE_ARCHS=all tags + +KBUILD_ENABLE_EXTRA_GCC_CHECKS +-------------------------------------------------- +If enabled over the make command line with "W=1", it turns on additional +gcc -W... options for more extensive build-time checking. + +KBUILD_BUILD_TIMESTAMP +-------------------------------------------------- +Setting this to a date string overrides the timestamp used in the +UTS_VERSION definition (uname -v in the running kernel). The value has to +be a string that can be passed to date -d. The default value +is the output of the date command at one point during build. + +KBUILD_BUILD_USER, KBUILD_BUILD_HOST +-------------------------------------------------- +These two variables allow to override the user@host string displayed during +boot and in /proc/version. The default value is the output of the commands +whoami and host, respectively. + +KBUILD_LDS +-------------------------------------------------- +The linker script with full path. Assigned by the top-level Makefile. + +KBUILD_VMLINUX_INIT +-------------------------------------------------- +All object files for the init (first) part of vmlinux. +Files specified with KBUILD_VMLINUX_INIT are linked first. + +KBUILD_VMLINUX_MAIN +-------------------------------------------------- +All object files for the main part of vmlinux. +KBUILD_VMLINUX_INIT and KBUILD_VMLINUX_MAIN together specify +all the object files used to link vmlinux. |