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Porting Hints
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Porting Hints
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<p>NOTE: The following procedures have been replaced by GNU automake and
autoconfigure. This page is to be updated in the next release.

<p>Porting to a new machine or operating system ordinarily requires
updating the <code>./machines</code> directory and the
<code>./compilers</code> directories in order to define the build
environment and autoconfigure means. You will probably have to modify
the <code>ntp_machines.h</code> file and <code>"l_stdlib.h"</code> files
as well. The two most famous trouble spots are the I/O code in
<code>./xntpd/ntp_io.c</code> and the clock adjustment code in
<code>./xntpd/ntp_unixclock.c</code>.

<p>These are the rules so that older bsd systems and the POSIX standard
system can coexist together.

<ol>

<li>If you use <code>select</code> then include
<code>"ntp_select.h"</code>. <code>select</code> is not standard, since
it is very system dependent as to where it is defined. The logic to
include the right system dependent include file is in
<code>"ntp_select.h"</code>.

<p><li>Always use POSIX definition of strings. Include
<code>"ntp_string.h"</code> instead of <code>&lt;string.h&gt;</code>.

<p><li>Always include <code>"ntp_malloc.h"</code> if you use
<code>malloc</code>.

<p><li>Always include <code>"ntp_io.h"</code> instead of
<code>&lt;sys/file.h&gt;</code> or <code>&lt;fnctl.h&gt;</code> to get
<code>O_*</code> flags.

<p><li>Always include <code>"ntp_if.h"</code> instead of
<code>&lt;net/if.h&gt;</code>.

<p><li>Always include <code>"ntp_stdlib.h"</code> instead of
<code>&lt;stdlib.h&gt;</code>.

<p><li>Define any special defines needed for a system in
<code>./include/ntp_machine.h</code> based on system identifier. This
file is included by the <code>"ntp_types.h"</code> file and should
always be placed first after the <code>&lt;&gt;</code> defines.

<p><li>Define any special library prototypes left over from the system
library and include files in the <code>"l_stdlib.h"</code> file. This
file is included by the <code>"ntp_stdlib.h"</code> file and should
ordinarily be placed last in the includes list.

<p><li>Don't define a include file by the same name as a system include
file.

</ol>

<p><code>"l_stdlib.h"</code> can contain any extra definitions that are
needed so that <code>gcc</code> will shut up. They should be controlled
by a system identifier and there should be a separate section for each
system. Really this will make it easier to maintain.

<p>See <code>include/ntp_machines.h</code> for the various compile time
options.

<p>When you are satisfied the port works and that other ports are not
adversely affected, please send <a href="patches.html">patches</a> for
the system files you have changed, as well as any documentation that
should be updated, including the advice herein.

<p>Good luck.

<hr><address>David L. Mills (mills@udel.edu)</address></body></html>
