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@c  require.t,v 1.9 2002/01/17 21:47:46 joel Exp

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@chapter Requirements

A fairly large amount of disk space is required to perform the build of the

GNU C/C++ Cross Compiler Tools for RTEMS. The following table may help in

assessing the amount of disk space required for your installation:

@example

+------------------------------------+--------------------------+

|              Component             |   Disk Space Required    |

+------------------------------------+--------------------------+

|        archive directory           |        40 Mbytes         |

|        tools src unarchived        |       200 Mbytes         |

|  each individual build directory   |     up to 500 Mbytes     |

|     each installation directory    |      20-200 Mbytes       |

+------------------------------------+--------------------------+

@end example

It is important to understand that the above requirements only address

the GNU C/C++ Cross Compiler Tools themselves.  Adding additional

languages such as Fortran or Objective-C can increase the size

of the build and installation directories.  Also, the unarchived

source and build directories can be removed after the tools are

installed.

After the tools themselves are installed, RTEMS must be built

and installed for each Board Support Package that you wish

to use.  Thus the precise amount of disk space required

for each installation directory depends highly on the number

of RTEMS BSPs which are to be installed.  If a single BSP is

installed, then the additional size of each install directory

will tend to be in the 40-60 Mbyte range.

There are a number of factors which must be taken into

account in oreder to estimate the amount of disk space required

to build RTEMS itself.  Attempting to build multiple BSPs in

a single step increases the disk space requirements.  Similarly

enabling optional features increases the build and install

space requirements.  In particular, enabling and building

the RTEMS tests results in a significant increase in build

space requirements but since the test are not installed has

no impact on installation requirements.

The instructions in this manual should work on any computer running

a UNIX variant.  Some native GNU tools are used by this procedure

including:

@itemize @bullet

@item GCC

@item GNAT

@item GNU make

@end itemize

In addition, some native utilities may be deficient for building

the GNU tools.

@section Native GNAT

The native GNAT must be installed in the default location or built

from source.  No GCC or GNAT environment variables should be set during

the build or use of the cross GNAT/RTEMS toolset as this could result in

an unpredictable mix of native and cross toolsets.

Binaries for native GNAT installations are available at the primary

GNAT ftp site (@value{GNAT-FTP}.   Installation instructions are

included with the binary GNAT distributions.  The binary installation

should be installed in the default location or installed in a

non-default location and used ONLY to build a native GNAT from source.

This final native GNAT will be used to build the GNAT/RTEMS cross

development toolset.

@subsection Verifying Correct Operation of Native GNAT

It is imperative that the native GNAT installation work correctly for

the installation of GNAT/RTEMS to succeed.  It is recommended that the

user verify that the native GNAT is installed correctly by performing

these tests:

@subsubsection Native Hello World Test

Place the following Ada source code in hello.adb:

@example

with Text_IO; use Text_IO;

procedure Hello is

begin

   Put_Line ( "Hello World");

end Hello;

@end example

Use the following command sequence to ompile and execute the above program:

@example

gnatmake hello

./hello

@end example

If the message @code{Hello World} is printed, then the native installation

of GNAT operates well enough to proceed.

@subsubsection Insure GCC and GNAT Environment Variables Are Not Set

If any of the following commands produce output, then you have

environment variables overriding the default behavior of the

native GNAT toolset.  These variables will conflict with the cross

toolset.  Please resolve this problem before proceeding further.

@example

echo $GCC_EXEC_PREFIX

echo $ADA_INCLUDE_PATH

echo $ADA_OBJECTS_PATH

echo $LD_RUN_PATH

echo $C_INCLUDE_PATH

@end example