Porting Hints

Last update: May 4, 2022 17:05 UTC (dbea9b7d4)

Porting Dorothy in Oz

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

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

1. If you use select then include ntp_select.h. select 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 ntp_select.h.
2. Always use POSIX definition of strings. Include ntp_string.h instead of <string.h>.
3. Always include ntp_malloc.h if you use malloc.
4. Always include ntp_io.h instead of <sys/file.h> or <fnctl.h> to get O_* flags.
5. Always include ntp_if.h instead of <net/if.h>.
6. Always include ntp_stdlib.h instead of <stdlib.h>.
7. Define any special defines needed for a system in ./include/ntp_machine.h based on system identifier. This file is included by the ntp_types.h file and should always be placed first after the <> defines.
8. Define any special library prototypes left over from the system library and include files in the l_stdlib.h file. This file is included by the ntp_stdlib.h file and should ordinarily be placed last in the includes list.
9. Don’t define a include file by the same name as a system include file.

l_stdlib.h can contain any extra definitions that are needed so that gcc 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.

See include/ntp_machines.h for the various compile time options.

When you are satisfied the port works and that other ports are not adversely affected, please send patches for the system files you have changed, as well as any documentation that should be updated, including the advice herein.

Good luck.