Documentation/kbuild/kbuild.txt

   1 Output files
   2
   3 modules.order
   4 --------------------------------------------------
   5 This file records the order in which modules appear in Makefiles. This
   6 is used by modprobe to deterministically resolve aliases that match
   7 multiple modules.
   8
   9 modules.builtin
  10 --------------------------------------------------
  11 This file lists all modules that are built into the kernel. This is used
  12 by modprobe to not fail when trying to load something builtin.
  13
  14
  15 Environment variables
  16
  17 KCPPFLAGS
  18 --------------------------------------------------
  19 Additional options to pass when preprocessing. The preprocessing options
  20 will be used in all cases where kbuild does preprocessing including
  21 building C files and assembler files.
  22
  23 KAFLAGS
  24 --------------------------------------------------
  25 Additional options to the assembler (for built-in and modules).
  26
  27 AFLAGS_MODULE
  28 --------------------------------------------------
  29 Addtional module specific options to use for $(AS).
  30
  31 KCFLAGS
  32 --------------------------------------------------
  33 Additional options to the C compiler (for built-in and modules).
  34
  35 CFLAGS_MODULE
  36 --------------------------------------------------
  37 Addtional module specific options to use for $(CC).
  38
  39 LDFLAGS_MODULE
  40 --------------------------------------------------
  41 Additional options used for $(LD) when linking modules.
  42
  43 KBUILD_VERBOSE
  44 --------------------------------------------------
  45 Set the kbuild verbosity. Can be assigned same values as "V=...".
  46 See make help for the full list.
  47 Setting "V=..." takes precedence over KBUILD_VERBOSE.
  48
  49 KBUILD_EXTMOD
  50 --------------------------------------------------
  51 Set the directory to look for the kernel source when building external
  52 modules.
  53 The directory can be specified in several ways:
  54 1) Use "M=..." on the command line
  55 2) Environmnet variable KBUILD_EXTMOD
  56 3) Environmnet variable SUBDIRS
  57 The possibilities are listed in the order they take precedence.
  58 Using "M=..." will always override the others.
  59
  60 KBUILD_OUTPUT
  61 --------------------------------------------------
  62 Specify the output directory when building the kernel.
  63 The output directory can also be specificed using "O=...".
  64 Setting "O=..." takes precedence over KBUILD_OUTPUT.
  65
  66 ARCH
  67 --------------------------------------------------
  68 Set ARCH to the architecture to be built.
  69 In most cases the name of the architecture is the same as the
  70 directory name found in the arch/ directory.
  71 But some architectures such as x86 and sparc have aliases.
  72 x86: i386 for 32 bit, x86_64 for 64 bit
  73 sparc: sparc for 32 bit, sparc64 for 64 bit
  74
  75 CROSS_COMPILE
  76 --------------------------------------------------
  77 Specify an optional fixed part of the binutils filename.
  78 CROSS_COMPILE can be a part of the filename or the full path.
  79
  80 CROSS_COMPILE is also used for ccache in some setups.
  81
  82 CF
  83 --------------------------------------------------
  84 Additional options for sparse.
  85 CF is often used on the command-line like this:
  86
  87     make CF=-Wbitwise C=2
  88
  89 INSTALL_PATH
  90 --------------------------------------------------
  91 INSTALL_PATH specifies where to place the updated kernel and system map
  92 images. Default is /boot, but you can set it to other values.
  93
  94 INSTALLKERNEL
  95 --------------------------------------------------
  96 Install script called when using "make install".
  97 The default name is "installkernel".
  98
  99 The script will be called with the following arguments:
 100     $1 - kernel version
 101     $2 - kernel image file
 102     $3 - kernel map file
 103     $4 - default install path (use root directory if blank)
 104
 105 The implmentation of "make install" is architecture specific
 106 and it may differ from the above.
 107
 108 INSTALLKERNEL is provided to enable the possibility to
 109 specify a custom installer when cross compiling a kernel.
 110
 111 MODLIB
 112 --------------------------------------------------
 113 Specify where to install modules.
 114 The default value is:
 115
 116      $(INSTALL_MOD_PATH)/lib/modules/$(KERNELRELEASE)
 117
 118 The value can be overridden in which case the default value is ignored.
 119
 120 INSTALL_MOD_PATH
 121 --------------------------------------------------
 122 INSTALL_MOD_PATH specifies a prefix to MODLIB for module directory
 123 relocations required by build roots.  This is not defined in the
 124 makefile but the argument can be passed to make if needed.
 125
 126 INSTALL_MOD_STRIP
 127 --------------------------------------------------
 128 INSTALL_MOD_STRIP, if defined, will cause modules to be
 129 stripped after they are installed.  If INSTALL_MOD_STRIP is '1', then
 130 the default option --strip-debug will be used.  Otherwise,
 131 INSTALL_MOD_STRIP will used as the options to the strip command.
 132
 133 INSTALL_FW_PATH
 134 --------------------------------------------------
 135 INSTALL_FW_PATH specifies where to install the firmware blobs.
 136 The default value is:
 137
 138     $(INSTALL_MOD_PATH)/lib/firmware
 139
 140 The value can be overridden in which case the default value is ignored.
 141
 142 INSTALL_HDR_PATH
 143 --------------------------------------------------
 144 INSTALL_HDR_PATH specifies where to install user space headers when
 145 executing "make headers_*".
 146 The default value is:
 147
 148     $(objtree)/usr
 149
 150 $(objtree) is the directory where output files are saved.
 151 The output directory is often set using "O=..." on the commandline.
 152
 153 The value can be overridden in which case the default value is ignored.
 154
 155 KBUILD_MODPOST_WARN
 156 --------------------------------------------------
 157 KBUILD_MODPOST_WARN can be set to avoid errors in case of undefined
 158 symbols in the final module linking stage. It changes such errors
 159 into warnings.
 160
 161 KBUILD_MODPOST_NOFINAL
 162 --------------------------------------------------
 163 KBUILD_MODPOST_NOFINAL can be set to skip the final link of modules.
 164 This is solely useful to speed up test compiles.
 165
 166 KBUILD_EXTRA_SYMBOLS
 167 --------------------------------------------------
 168 For modules that use symbols from other modules.
 169 See more details in modules.txt.
 170
 171 ALLSOURCE_ARCHS
 172 --------------------------------------------------
 173 For tags/TAGS/cscope targets, you can specify more than one arch
 174 to be included in the databases, separated by blank space. E.g.:
 175
 176     $ make ALLSOURCE_ARCHS="x86 mips arm" tags
 177
 178 To get all available archs you can also specify all. E.g.:
 179
 180     $ make ALLSOURCE_ARCHS=all tags