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<!doctype linuxdoc system>
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<title>NetWare Loadable Module Programming HOWTO
<author>Martin Hinner, &lt;<htmlurl url=""
<date>Version 0.2, 04 August 2000
This document describes how to develop NetWare Loadable Modules under Linux,
using GNU CC and nlmconv(1) from GNU binutils. This is not an official Novell
document; I wrote it without any help or cooperation from
<htmlurl url="" name="Novell, Inc.">
NetWare Loadable Modules (NLMs) are programs which run on Novell NetWare
server. NLMs become part of the NetWare OS. You can load and unload NLMs while
the server is running. <p>
"Official" compilers for NLMs are:
<item> Watcom C/C++
<item> Metrowerks Codewarrior for NetWare (see <url url="">)
<item> EPC C/C++ (see <url url="">)
<item> Novell NLMLINK.EXE
(On a side note, NetWare 5 can also load 32bit DLLs, which can be built using Microsoft Visual
C++, Borland C++ and other Windows compilers. For more information see
<url url="">)
This document describes how to get started with NLM development under Linux (and
possibly other Unixes). Please note that this project is in very early
stages of development, so a lot of things may not work as you'd expect.
This document assumes that you are familiar with Novell NetWare, and that you
have at least basic knowledge of writing NLMs. For more information about
writing NLMs, see Novell's developer site,
<url url="">. You should also have experience
with Unix and C/C++ programming with GNU CC. You can find a lot of information
about this topic at <url url="">.
<sect1>C++ Development<p>
As far as I know, C++ development with gcc is currently impossible,
till somebody ports at least the libstdc++ and libgcc
libraries from the gcc package.
<sect1>Related Documentation<p>
Other documents that might be useful are:
<item>The <bf>IPX-HOWTO</bf>, which describes the details of configuring IPX
protocol on Linux.
<item>The <bf>Linux GCC HOWTO</bf>, which covers how to set up the GNU C compiler and
development libraries under Linux, and gives an overview of compiling,
linking, running and debugging programs under it.
<item>The <bf>Assembly HOWTO</bf>, which describes how to
program in assembly language using FREE programming tools, focusing on
development for or from the Linux Operating System on the i386 platforms.
<item>The <bf>Creating NLMs on Linux x86</bf>,
<url url="">, by Gabor Keresztvalvi
&lt;;. His page describes the same thing as my HOWTO.
I found Gabor's page ten days after releasing version 0.1 of this document :( .
Copyright (c) 2000 Martin Hinner, &lt;<htmlurl url=""
This HOWTO is Free documentation; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
This document is distributed in the hope that it will be useful,
but without any warranty; without even the implied warranty of
merchantability or fitness for a particular purpose. See the GNU
General Public License for more details.
You can obtain a copy of the GNU General Public License by writing
to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA
02139, USA.
<sect>Setting Up Your Linux Box and NetWare Server<p>
You need to install and configure these things for NLM development:
<item> Linux box with configured IPX and NCPFS
<item> GNU C compiler (gcc) for elf-i386
(nearly all i386 Linux Distributions include it)
<item> GNU binutils with nlmconv(1) program
<item> My nlm-kit package
<item> Novell Developer Kit - NDK (include files and documentation)
<item> DOSemu (with rconsole) or X11 server for running NetWare Xconsole.
<item> ... and, finally, NetWare server :-)
You might also want to download the nlm-examples package from my FTP site:
<url url=""> or
<url url="">.
<sect1>Novell NetWare Server<p>
Let's start with the NetWare server. You can use NetWare versions 3.X, 4.X
or 5.X.
NetWare 5 (or 5.1) three user "demo" version can be ordered from
Novell Inc. for a few dollars. Don't be confused with word "demo", it's fully
functional NetWare, except that it is limited to three users. By the way, this license can
be upgraded online, at no cost, to five users. You might also try asking your
local Novell partner for demo CDs (they may be free).
<sect1>Linux Box With IPX/NCPFS<p>
You need to recompile your kernel with "The IPX protocol" and
"NCP file system support" options enabled. Don't forget to say YES to
"NDS authentication support" if you are using the NDS. Then you must
configure the IPX protocol and mount your NetWare server volumes.
Make sure that you
have installed the ncpfs package! I use this script:
ipx_interface delall
ipx_interface add -p eth0 802.2 120 # Frame Ethernet_802.2, ipx net num 120
insmod ncpfs # I have NCPfs compiled as module
ncpmount -U admin -S elf -P XYZ /nw # mount all ELF's volumes as /nw
For more information about configuring IPX and NCPFS, see the IPX-HOWTO.
<sect1>GNU C Compiler<p>
I think that all modern Linuxes for the Intel x86 include gcc, which generates
ELF32/i386 object files. If you have an older Linux distribution, it may
use the a.out format instead of ELF. If your Linux doesn't use ELF, get and
install a newer gcc.
<sect1>nlmconv(1) from GNU binutils<p>
The nlmconv(1) utility links object files to the NLM format. It is a standard
part of GNU binutils, but unfortunately it is not included in current distributions (RedHat,
SuSE, Debian, ...). Get the binutils sources from, and compile them, or
simply use the pre-compiled nlmconv from my nlm-kit package.
<sect1>The nlm-kit Package<p>
My nlm-kit package is avaliable from
<url url="">. It contains necessary
files for NLM development. Extract it and run <tt>"make all"</tt> and
<tt>"make install"</tt>.
It will create the directory <tt>/usr/nwsdk/</tt> and install all import files,
object files and the nlmimp(1) utility.
<sect1>Include Files and Documentation from the NDK<p>
Getting the NDK is easy:
<item> Download it from <url url="">.
<item> Order two NDK CDs from Novell.
<item> Get these CDs at no cost at BrainShare, Novell Developer Workshop
or at other Novell Developer events.
You need these files from the NDK (all are available online at
<url url="">:
<item> C language header and import files (cdrom:\files\download\clib.exe)
<item> C language API documentation (cdrom:\files\download\clib_doc.exe)
<item> C language samples (optional) (cdrom:\files\download\clib_sample.exe)
It's a pity that all the files mentioned above are InstallShield Win32 executables.
You must find some Windows machine to extract them and then copy the include files
to <tt>/usr/nwsdk/include/</tt> and documentation/samples to anywhere you want.
The Novell License doesn't allow me to distribute include files or documentation
with the nlm-kit.<p>
Because the NDK include files don't work under Linux, you need to patch
them manually by typing "make install-include" in the nlm-kit-X.Y/
<sect1>Access to the NetWare Server (Xconsole or rconsole)<p>
You can access the NetWare server console directly (keyboard and monitor),
using rconsole.exe (from dosemu), or using telnetd.nlm/Xconsole (you need
X server for this).
<sect>First Step: Hello world<p>
As usual, we will start with the famous "Hello world" program. The source
code for hello.nlm is available in the nlm-samples package. You can download
it from <url url="">.
<sect1>hello.c - Source File<p>
#define N_PLAT_NLM /* Define dest. platform */
#include <nwconio.h> /* ConsolePrintf */
main (int argc, char **argv)
int i;
ConsolePrintf ("\rHello world!\n\n"); /* print on system console */
ConsolePrintf("Arguments:\n"); /* all arguments */
for (i=0;i<argc;i++)
ConsolePrintf("argv[%u]=\"%s\"\n",i, argv[i]);
return 0; /* exit NLM */
<sect1>hello.def - NLM header file<p>
# hello.def - NLM Header definition file for nlmconv(1)
# Copyright (c) 2000 Martin Hinner <>
# define startup object files
INPUT hello.o
INPUT /usr/nwsdk/lib/prelude.o # clib startup code
# all imported functions and import lists
IMPORT @/usr/nwsdk/imports/clib.imp # Functions in CLIB.NLM
IMPORT @/usr/nwsdk/imports/threads.imp # Functions in THREADS.NLM
# NLM header...
OUTPUT hello.nlm # output file
TYPE 0 # Ordinary NLM
VERSION 1,0,0 # Version 1.0
COPYRIGHT "Copyright (c) 2000 Martin Hinner <>" # (c) ...
DESCRIPTION "Simple 'Hello world' NLM module." # title of nlm
SCREENNAME "System Console" # Default screen name
MODULE CLIB,THREADS # req'd modules
# makefile for "hello world" NLM
CC = gcc
CFLAGS = -Wall -O2 -g -I/usr/nwsdk/include/ -nostdinc -fno-builtin -fpack-struct
hello.nlm: hello.o hello.def
nlmconv --output-target=nlm32-i386 -T hello.def
hello.o: hello.c
$(CC) $(CFLAGS) -c hello.c
<sect1>GCC problems<p>
You must pass these arguments to the gcc:
<item> <bf>-fno-builtin</bf>:
GCC's fast builtin functions sometimes cause server to abend,
so we don't want to use them.
<item> <bf>-nostdinc</bf>:
Only include files in /usr/nwsdk/include are valid for NLMs (don't
forget to use also -I/usr/nwsdk/include).
<item> <bf>-fpack-struct</bf>:
GCC's struct packing method is not valid for Novell NetWare, so we
won't use it. Thanks to Gabor Keresztvalvi for this information.
<sect1>Testing the Module<p>
Copy hello.nlm to the SYS:\SYSTEM directory on your NetWare server. Then, on
the system console, type "load hello.nlm". If everything went fine, you should
see NLM version information, a copyright message and "Hello world".
<sect>NLM Header file<p>
The NLM header file contains information for <em>nlmconv(1)</em>. Each
line contains one option or directive; everything after "#" is comment.
This chapter describes all options and directives.
This chapter is not yet finished, sorry.
<bf>CHECK &lt;check procedure name&gt;</bf><p>
This directive specifies the function to be
executed when the NLM is unloaded using the <em>UNLOAD</em> Server console
command. If this function returns zero, the NLM can be unloaded, else
the NLM is not ready to be unloaded.
CHECK CheckUnload
<bf>CODESTART &lt;map file code start offset&gt;</bf><p>
Map file start offset may be decimal or Xhex.
<bf>COPYRIGHT ["Copyright string"]</bf>
The copyright string is displayed on the server console screen when the
NLM is loaded. If this option is not used, no copyright information is
COPYRIGHT "Copyright (c) 1998 ABC Inc."
<bf>CUSTOM &lt;custom data file path&gt;</bf><p>
<bf>DATASTART &lt;map file data start offset&gt;</bf><p>
Map file data start offset may be decimal or Xhex.
<bf>DATE &lt;month, day, year&gt;</bf><p>
This directive tells the nlmconv(1) to include debugging information in
the NLM file.
<bf>DESCRIPTION "NLM Description String"</bf><p>
<bf>EXIT &lt;exit procedure name&gt;</bf><p>
<bf>EXPORT &lt;symbol list&gt;</bf><p>
<bf>EXPORT @&lt;symbol list file&gt;</bf><p>
<bf>FLAG_OFF &lt;decimal number&gt;</bf><p>
<bf>FLAG_ON &lt;decimal number&gt;</bf><p>
<bf>HELP &lt;help file path&gt;</bf><p>
<bf>IMPORT &lt;symbol list&gt; </bf><p>
<bf>IMPORT @&lt;symbol list file&gt;</bf><p>
<bf>INPUT &lt;object file&gt; [, &lt;object file&gt; [, ...] ]</bf><p>
<bf>INPUT @&lt;object list file&gt;</bf><p>
This directive lists the input ELF (.o) object files that are to be linked.
You can also list the object files in the list file, each object file on
one line.
INPUT @objectfiles.txt
INPUT main.o
INPUT /usr/nwsdk/lib/prelude.o
<bf>MAP [map file name]</bf><p>
<bf>MESSAGES &lt;message file path&gt;</bf><p>
<bf>MODULE &lt;autoload NLM list&gt;</bf><p>
<bf>NAMELEN &lt;decimal number&gt;</bf><p>
Default is 31. Zero is no limit.<p>
<bf>OUTPUT &lt;target file name&gt;</bf><p>
<bf>PATH [search path;...]</bf><p>
<bf>SCREENNAME "Initial Screen Name (CLIB)"</bf><p>
<bf>SHARELIB &lt;shared library path&gt;</bf><p>
<bf>STACK &lt;stack size&gt;</bf><p>
<bf>STACKSIZE &lt;stack size&gt;</bf><p>
<bf>STAMPEDDATA "Stamp" &lt;data file path&gt;</bf><p>
Stamp is 8 char max.
<bf>START &lt;start procedure name&gt;</bf><p><p>
Default is _Prelude.
<bf>THREADNAME "Initial Process Name (CLIB)"</bf><p>
<bf> TYPE &lt;version&gt;</bf><p>
This directive specifies the format (NLM, LAN, DSK, NAM) of
the NLM file to be generated. Valid values are:
<item> 0 - NLM
<item> 1 - LAN
<item> 2 - DSK
<item> 3 - NAM
<bf>VERSION &lt;major version&gt;, &lt;minor version&gt;
[, &lt;revision&gt;]</bf><p>
The version information is displayed on the server system console when the NLM
loads. The major and minor version numbers can be 0 - 99. The revision
can be 0 - 26 ("a" - "z") and is optional. <bf>The version directive is
<bf>XDCDATA &lt;XDC data file path&gt;</bf><p>
<sect>Message files<p>
A message file contains (as you guess) text messages generated by the NLM. You can create it
using DOS programs MSGLIB.EXE and MSGMAKE.EXE. I don't know any similar utility
for Unix. Sorry, you'll have to use dosemu or DOS machine :-(
<sect>Help Files<p>
Help files contain help for use with the NWSNUT user interface library.
There is no known Linux utility for creating help files. You must use
the DOS program HELPLIB.EXE, which is available from Novell developer site.
<sect>XDC Data Files<p>
XDC files are used by NetWare 5 (or SMP NetWare 4.x), and store information
about symmetric multiprocessing (SMP). You will probably not need them. At least
not now :-) Again, there is no Unix utility for creating XDC files,
you will have to use the MPKXDC.EXE program (also available on the Novell
developer site).<p>
<sect>Header Files (.h)<p>
<sect>Import Files (.imp)<p>
<sect1>Generating Import Files Using nlmimp(1)<p>
Program nlmimp(1) is part of my nlm-kit package. (todo)