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+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.