Книга: Embedded Linux Primer: A Practical, Real-World Approach

4.3.3. Makefile Targets

4.3.3. Makefile Targets

If you type make help at the top-level Linux source directory, you are presented with a list of targets that can be generated from the source tree. The most common use of make is to specify no target. This generates the kernel ELF file vmlinux and is the default binary image for your chosen architecture (for example, bzImage for x86). Specifying make with no target also builds all the device-driver modules (kernel-loadable modules) specified by the configuration.

Many architectures and machine types require binary targets specific to the architecture and bootloader in use. One of the more common architecture specific targets is zImage. In many architectures, this is the default target image that can be loaded and run on the target embedded system. One of the common mistakes that newcomers make is to specify bzImage as the make target. The bzImage target is specific to the x86/PC architecture. Contrary to popular myth, the bzImage is not a bzip2 -compressed image. It is a big zImage. Without going into the details of legacy PC architecture, it is enough to know that a bzImage is suitable only for PC-compatible machines with an industry-standard PC-style BIOS.

Listing 4-7 contains the output from make help from a recent Linux kernel. You can see from the listing that many targets are available in the top-level Linux kernel makefile. Each is listed along with a short description of its use. It is important to realize that even the help make target (as in make help) is architecture specific. You get a different list of architecture-specific targets depending on the architecture you pass on the make invocation. Listing 4-7 illustrates an invocation that specifies the ARM architecture, as you can see from the make command line.

Listing 4-7. Makefile Targets

$ make ARCH=arm help
Cleaning targets:
  clean            -  remove most generated files but keep the config
  mrproper         -  remove all generated files + config +  various backup files
Configuration targets:
  config           -  Update current config utilising a line-oriented program
  menuconfig       -  Update current config utilising a menu based program
  xconfig          -  Update current config utilising a QT based front-end
  gconfig          -  Update current config utilising a GTK based front-end
  oldconfig        -  Update current config utilising a provided .config as base
  randconfig       -  New config with random answer to all options
  defconfig        -  New config with default answer to all options
  allmodconfig     -  New config selecting modules when possible
  allyesconfig     -  New config where all options are accepted with yes
  allnoconfig      -  New minimal config
Other generic targets:
  all              - Build all targets marked with [*]
* vmlinux          - Build the bare kernel
* modules          - Build all modules
  modules_install  - Install all modules
  dir/             - Build all files in dir and below
  dir/file.[ois]   - Build specified target only
  dir/file.ko      - Build module including final link
  rpm              - Build a kernel as an RPM package
  tags/TAGS        - Generate tags file for editors
  cscope           - Generate cscope index
  kernelrelease    - Output the release version string
Static analysers
  buildcheck       - List dangling references to vmlinux discarded sections and
                     init sections from non-init sections
  checkstack       - Generate a list of stack hogs
  namespacecheck   - Name space analysis on compiled kernel
Kernel packaging:
  rpm-pkg          - Build the kernel as an RPM package
  binrpm-pkg       - Build an rpm package containing the compiled kernel and
                     modules
deb-pkg          - Build the kernel as an deb package
  tar-pkg          - Build the kernel as an uncompressed tarball
  targz-pkg        - Build the kernel as a gzip compressed tarball
  tarbz2-pkg       - Build the kernel as a bzip2 compressed tarball
Documentation targets:
  Linux kernel internal documentation in different formats:
  xmldocs (XML DocBook), psdocs (Postscript), pdfdocs (PDF)
  htmldocs (HTML), mandocs (man pages, use installmandocs to install)
Architecture specific targets (arm):
* zImage           -  Compressed kernel image (arch/arm/boot/zImage)
  Image            -  Uncompressed kernel image (arch/arm/boot/Image)
* xipImage         - XIP kernel image, if configured (arch/arm/boot/xipImage)
  bootpImage       - Combined zImage and initial RAM disk
                     (supply initrd image via make variable INITRD=<path>)
  install           - Install uncompressed kernel
  zinstall          - Install compressed kernel
                     Install using (your) ~/bin/installkernel or
                     (distribution) /sbin/installkernel or
                     install to $(INSTALL_PATH) and run lilo
  assabet_defconfig          - Build for assabet
  badge4_defconfig           - Build for badge4
  bast_defconfig             - Build for bast
  cerfcube_defconfig         - Build for cerfcube
  clps7500_defconfig         - Build for clps7500
  collie_defconfig           - Build for collie
  corgi_defconfig            - Build for corgi
  ebsa110_defconfig          - Build for ebsa110
  edb7211_defconfig          - Build for edb7211
  enp2611_defconfig          - Build for enp2611
  ep80219_defconfig          - Build for ep80219
  epxa10db_defconfig         - Build for epxa10db
  footbridge_defconfig       - Build for footbridge
  fortunet_defconfig         - Build for fortunet
  h3600_defconfig            - Build for h3600
  h7201_defconfig            - Build for h7201
  h7202_defconfig            - Build for h7202
  hackkit_defconfig          - Build for hackkit
  integrator_defconfig       - Build for integrator
  iq31244_defconfig          - Build for iq31244
  iq80321_defconfig          - Build for iq80321
  iq80331_defconfig          - Build for iq80331
  iq80332_defconfig          - Build for iq80332
  ixdp2400_defconfig         - Build for ixdp2400
  ixdp2401_defconfig         - Build for ixdp2401
  ixdp2800_defconfig         - Build for ixdp2800
  ixdp2801_defconfig         - Build for ixdp2801
  ixp4xx_defconfig           - Build for ixp4xx
  jornada720_defconfig       - Build for jornada720
  lart_defconfig             - Build for lart
  lpd7a400_defconfig         - Build for lpd7a400
  lpd7a404_defconfig         - Build for lpd7a404
  lubbock_defconfig          - Build for lubbock
lusl7200_defconfig         - Build for lusl7200
  mainstone_defconfig        - Build for mainstone
  mx1ads_defconfig           - Build for mx1ads
  neponset_defconfig         - Build for neponset
  netwinder_defconfig        - Build for netwinder
  omap_h2_1610_defconfig     - Build for omap_h2_1610
  pleb_defconfig             - Build for pleb
  poodle_defconfig           - Build for poodle
  pxa255-idp_defconfig       - Build for pxa255-idp
  rpc_defconfig              - Build for rpc
  s3c2410_defconfig          - Build for s3c2410
  shannon_defconfig          - Build for shannon
  shark_defconfig            - Build for shark
  simpad_defconfig           - Build for simpad
  smdk2410_defconfig         - Build for smdk2410
  spitz_defconfig            - Build for spitz
  versatile_defconfig        - Build for versatile
  make V=0|1 [targets] 0 => quiet build (default), 1 => verbose build
  make O=dir [targets] Locate all output files in "dir", including .config
  make C=1   [targets] Check all c source with $CHECK (sparse)
  make C=2   [targets] Force check of all c source with $CHECK (sparse)
Execute "make" or "make all" to build all targets marked with [*]
For further info see the ./README file

Many of these targets you might never use. However, it is useful to know that they exist. As you can see from Listing 4-7, the targets listed with an asterisk are built by default. Notice the numerous default configurations, listed as *_defconfig. Recall from Section 4.2.2, "Compiling the Kernel," the command we used to preconfigure a pristine kernel source tree: We invoked make with an architecture and a default configuration. The default configuration was ixp4xx_defconfig, which appears in this list of ARM targets. This is a good way to discover all the default configurations available for a particular kernel release and architecture.

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