build - compile and install the kernel

     build [compile-options ...]

     Build compiles the kernel sources found in a  subdirectory  of  /usr/src,
     (usually /usr/src/sys) and installs the resulting kernel image in /minix.
     Build must be called from some subdirectory in the selected kernel source
     directory  if  it  is  to  know  what  it  must  compile.   It  will  use
     /usr/src/sys if called from /usr/src.

     The kernel source tree has the following subdirectories:

          The Minix kernel, the lowest layer of the  operating  system.   (The
          word  "kernel"  is  used both for this part of the operating system,
          and for the whole combination.  What is meant is usually clear  from

     mm   The Memory Manager.

     fs   The File System.

          Contains an "init" stub routine that calls /sbin/init.   Init  needs
          not be present in the image at boot time, so it has been replaced by
          a small stub.  (It could be put back if so needed.)

     inet The sources of the internetworking task.   Build  will  not  compile
          this  task.   Init  and  inet  are  seen  as normal commands and are
          therefore compiled from the central Makefile.

          Contains the central Makefile to compile all the  kernel  parts  and
          make  an  image.  Usually contains the same images as /minix and all
          the images created in the last week.   The  default  action  of  the
          Makefile  is  to create a kernel image.  Other possible actions are:
          make depend, to generate Makefile dependencies, make clean, to clean
          the source tree of intermediate files, and make bootable, to install
          a new bootstrap and boot code into the root file system.

          Contains the files version.h and revision.c.  The  first  tells  the
          O.S. release and version strings.  The second is the revision number
          of the kernel, it is automatically increased by one  each  time  you
          call  build.   The  concatenation  of  release, version and revision
          numbers is used to name the image in the tools directory and /minix.

     Before build is called for the first time an important decision  must  be
     made.  Do you want to do the compilation in the source directory, or in a
     so-called "build-tree" full of links to the source directory?  The former
     pollutes  your  source  directory  with .o files and executables, but the
     latter requires a lot of discipline to maintain the links.  If you decide
     to  use  a  build-tree  (see  @build(8)  for more) then use the following
     commands to create it:

          cd /usr/src

     When executed build will simply call make in the tools directory to  make
     a  new  image.   There is nothing sinister going on, you can type make in
     the many kernel directories yourself if you want to, all that build  does
     extra  is  manage  the  images in tools and /minix.  Any options given to
     build are attached to the CFLAGS variable in the many Makefiles using the
     OPT environment variable.  (So build -O is the same as OPT=-O make ...)

     There are usually two images in /minix.  One that is known to  work,  and
     one experimental.  After build has made a new image it will ask which one
     of these to remove.  By default it will want to remove  the  experimental
     (newest) image.  You can use wildcards (*, ?) in your answer, or 'foo' or
     anything else if you want to remove nothing.  No questions are  asked  if
     there are no images or just one image in /minix.

     The first new kernel you would like to make is one  configured  for  your
     system.   The  kernel  you  are  running  now  contains several hard disk
     drivers you don't need, so you may want to kick them out to  save  a  few
     bytes.   In  the  file  config.h  in  the kernel directory you can find a
     number of ENABLE_XXX variables that can be set to 0 to exclude, or  1  to
     include   a  particular  driver.   Another  driver  related  variable  is
     DMA_SECTORS.  This variable sets the size of a buffer used by  DMA  based
     disk  drivers  (all  but the floppy, AT, and Adaptec drivers).  Raise its
     value to greatly improve throughput, especially writing.  A value  of  16
     shows good results.  (Has no effect on old interleaved drives.)


          Called from the task makefiles to increase the revision number.  Not
          normally called by the user.


     /usr/src/sys        Default  kernel  source  directory   and   associated

     /minix              Image directory.

     make(1), @build(8), usage(8).

     The revision number will only be increased in  the  kernel,  mm,  and  fs
     directories,  not  on a change in task.stubs for instance.  So be careful
     at the "removal" prompt.

     Kees J. Bot (