path: root/doc/started/buildrt.t
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@c  COPYRIGHT (c) 1988-2002.
@c  On-Line Applications Research Corporation (OAR).
@c  All rights reserved.
@c  $Id$

@chapter Building RTEMS

@section Obtain the RTEMS Source Code

This section provides pointers to the RTEMS source code and
Hello World example program.  These files should be
placed in your @code{archive} directory.  

@subheading @value{RTEMSVERSION}
    FTP Site:    @value{RTEMSFTPSITE}
    Directory:   @value{RTEMSFTPDIR}/@value{VERSION}
    File:        @value{RTEMSTAR}
@ifset use-html
@c    URL:         @uref{ftp://@value{RTEMSFTPSITE}@value{RTEMSFTPDIR}/@value{VERSION}, Download RTEMS components}
    URL:         ftp://@value{RTEMSFTPSITE}@value{RTEMSFTPDIR}/@value{VERSION}
@end ifset
@end example

@subheading RTEMS Examples including Hello World
    FTP Site:    @value{RTEMSFTPSITE}
    Directory:   @value{RTEMSFTPDIR}/@value{VERSION}
    File:        examples-@value{VERSION}.tar.bz2
    URL:         @uref{ftp://@value{RTEMSFTPSITE}@value{RTEMSFTPDIR}/@value{VERSION}/examples-@value{VERSION}.tar.bz2,,ftp://@value{RTEMSFTPSITE}@value{RTEMSFTPDIR}/@value{VERSION}/examples-@value{VERSION}.tar.bz2}
@end example

@c  Unarchive the RTEMS Source

@section Unarchive the RTEMS Source

Use the following command sequence to unpack the RTEMS source into the
tools directory: 

cd tools
tar xzf ../archive/@value{RTEMSTAR}
@end example

This creates the directory @value{RTEMSUNTAR}.

@section Add <INSTALL_POINT>/bin to Executable PATH

In order to compile RTEMS, you must have the cross compilation toolset
in your search path.  The following command appends the directory
where the tools were installed prior to this point:

@end example

NOTE:  The above command is in Bourne shell (@code{sh}) syntax and
should work with the Korn (@code{ksh}) and GNU Bourne Again Shell
(@code{bash}).  It will not work with the C Shell (@code{csh}) or
derivatives of the C Shell.

@section Verifying the Operation of the Cross Toolset

In order to insure that the cross-compiler is invoking the correct
subprograms (like @code{as} and @code{ld}), one can test assemble
a small program.  When in verbose mode, @code{gcc} prints out information 
showing where it found the subprograms it invokes.  In a temporary
working directory, place the following function in a file named @code{f.c}:

int f( int x )
  return x + 1;
@end example

Then assemble the file using a command similar to the following:

m68k-rtems-gcc -v -S f.c
@end example

Where @code{m68k-rtems-gcc} should be changed to match the installed
name of your cross compiler.  The result of this command will be
a sequence of output showing where the cross-compiler searched for
and found its subcomponents.  Verify that these paths correspond
to your <INSTALL_POINT>.

Look at the created file @code{f.s} and verify that it is in fact
for your target processor.

Then try to compile the file @code{f.c} directly to object code
using a command like the following:

m68k-rtems-gcc -v -c f.c
@end example

If this produces messages that indicate the assembly code is
not valid, then it is likely that you have fallen victim to 
one of the problems described in
@ref{Error Message Indicates Invalid Option to Assembler}
Don't feel bad about this, one of the most common installation errors
is for the cross-compiler not to be able to find the cross assembler
and default to using the native @code{as}.  This can result in very confusing
error messages.

@section Building RTEMS for a Specific Target and BSP

This section describes how to configure and build RTEMS 
so that it is specifically tailored for your BSP and the
CPU model it uses.  There is currently only one supported
method to compile and install RTEMS:

@itemize @bullet
@item direct invocation of @code{configure} and @code{make}
@end itemize

Direct invocation of @code{configure} and @code{make} provides more control
and easier recovery from problems when building. 

This section describes how to build RTEMS.

@subsection Using the RTEMS configure Script Directly

Make a build directory under tools and build the RTEMS product in this
directory. The @code{../@value{RTEMSUNTAR}/configure}
command has numerous command line
arguments. These arguments are discussed in detail in documentation that
comes with the RTEMS distribution. A full list of these arguments can be
obtained by running @code{../@value{RTEMSUNTAR}/configure --help}
If you followed the procedure
described in the section @ref{Unarchive the RTEMS Source}, these
configuration options can be found in the file

@b{NOTE}: The GNAT/RTEMS run-time implementation is based on the POSIX
API.  Thus the RTEMS configuration for a GNAT/RTEMS environment MUST
include the @code{--enable-posix} flag.

The following shows the command sequence required to configure,
compile, and install RTEMS with the POSIX API, FreeBSD TCP/IP,
and C++ support disabled.  RTEMS will be built to target 
the @code{BOARD_SUPPORT_PACKAGE} board.

mkdir build-rtems
cd build-rtems
../@value{RTEMSUNTAR}/configure --target=<TARGET_CONFIGURATION> \
    --disable-posix --disable-networking --disable-cxx \
make all install
@end example

Where the list of currently supported <TARGET_CONFIGURATION>'s and
<BOARD_SUPPORT_PACKAGE>'s can be found in

<INSTALL_POINT> is typically the installation point for the 
tools and defaults to @code{@value{RTEMSPREFIX}}.

BSP is a supported BSP for the selected CPU family.  The list of
supported BSPs may be found in the file
in the RTEMS source tree.  If the BSP parameter is not specified,
then all supported BSPs for the selected CPU family will be built.

@b{NOTE:}  The POSIX API must be enabled to use GNAT/RTEMS.

@b{NOTE:} The @code{make} utility used should be GNU make.