acc08b516f
Add kbuild.txt to Documentation/kbuild More stuff can be added later - at least we have som of the varous environment variables documented now. Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
126 lines
4.2 KiB
Text
126 lines
4.2 KiB
Text
Environment variables
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KCPPFLAGS
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--------------------------------------------------
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Additional options to pass when preprocessing. The preprocessing options
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will be used in all cases where kbuild do preprocessing including
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building C files and assembler files.
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KAFLAGS
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--------------------------------------------------
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Additional options to the assembler.
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KCFLAGS
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--------------------------------------------------
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Additional options to the C compiler.
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KBUILD_VERBOSE
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--------------------------------------------------
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Set the kbuild verbosity. Can be assinged same values as "V=...".
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See make help for the full list.
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Setting "V=..." takes precedence over KBUILD_VERBOSE.
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KBUILD_EXTMOD
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--------------------------------------------------
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Set the directory to look for the kernel source when building external
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modules.
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The directory can be specified in several ways:
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1) Use "M=..." on the command line
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2) Environmnet variable KBUILD_EXTMOD
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3) Environmnet variable SUBDIRS
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The possibilities are listed in the order they take precedence.
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Using "M=..." will always override the others.
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KBUILD_OUTPUT
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--------------------------------------------------
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Specify the output directory when building the kernel.
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The output directory can also be specificed using "O=...".
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Setting "O=..." takes precedence over KBUILD_OUTPUT
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ARCH
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--------------------------------------------------
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Set ARCH to the architecture to be built.
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In most cases the name of the architecture is the same as the
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directory name found in the arch/ directory.
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But some architectures suach as x86 and sparc has aliases.
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x86: i386 for 32 bit, x86_64 for 64 bit
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sparc: sparc for 32 bit, sparc64 for 64 bit
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CROSS_COMPILE
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--------------------------------------------------
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Specify an optional fixed part of the binutils filename.
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CROSS_COMPILE can be a part of the filename or the full path.
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CROSS_COMPILE is also used for ccache is some setups.
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CF
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--------------------------------------------------
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Additional options for sparse.
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CF is often used on the command-line like this:
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make CF=-Wbitwise C=2
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INSTALL_PATH
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--------------------------------------------------
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INSTALL_PATH specifies where to place the updated kernel and system map
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images. Default is /boot, but you can set it to other values
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MODLIB
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--------------------------------------------------
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Specify where to install modules.
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The default value is:
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$(INSTALL_MOD_PATH)/lib/modules/$(KERNELRELEASE)
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The value can be overridden in which case the default value is ignored.
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INSTALL_MOD_PATH
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--------------------------------------------------
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INSTALL_MOD_PATH specifies a prefix to MODLIB for module directory
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relocations required by build roots. This is not defined in the
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makefile but the argument can be passed to make if needed.
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INSTALL_MOD_STRIP
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--------------------------------------------------
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INSTALL_MOD_STRIP, if defined, will cause modules to be
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stripped after they are installed. If INSTALL_MOD_STRIP is '1', then
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the default option --strip-debug will be used. Otherwise,
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INSTALL_MOD_STRIP will used as the options to the strip command.
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INSTALL_FW_PATH
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--------------------------------------------------
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INSTALL_FW_PATH specify where to install the firmware blobs.
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The default value is:
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$(INSTALL_MOD_PATH)/lib/firmware
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The value can be overridden in which case the default value is ignored.
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INSTALL_HDR_PATH
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--------------------------------------------------
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INSTALL_HDR_PATH specify where to install user space headers when
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executing "make headers_*".
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The default value is:
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$(objtree)/usr
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$(objtree) is the directory where output files are saved.
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The output directory is often set using "O=..." on the commandline.
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The value can be overridden in which case the default value is ignored.
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KBUILD_MODPOST_WARN
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--------------------------------------------------
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KBUILD_MODPOST_WARN can be set to avoid error out in case of undefined
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symbols in the final module linking stage.
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KBUILD_MODPOST_FINAL
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--------------------------------------------------
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KBUILD_MODPOST_NOFINAL can be set to skip the final link of modules.
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This is solely usefull to speed up test compiles.
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KBUILD_EXTRA_SYMBOLS
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--------------------------------------------------
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For modules use symbols from another modules.
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See more details in modules.txt.
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