libopc/third_party/libxml2-2.7.7/VxWorks

libxml2 on VxWorks 6.4+

Here are my instructions for building on VxWorks.... I am very ashamed of
how I did this because it is a complete hack, but it works great, so I
can't complain too much.

General Information

1. The only way to build for VxWorks is to cross compile from a windows or
linux system. We use a RedHat 5.1 workstation system as our build
environment.

2. VxWorks 6.X has two main types of executable, DKMs (dynamic kernel
modules), and RTPs (real-time processes). Kernel modules are the bread
and butter of VxWorks, but they look nothing like processes/threads in
normal UNIX/Windows systems. RTPs are more like processes that have
memory protection, threads, etc. VxWorks 6.X also introduces some level
of POSIX conformance to their environment. The POSIX conformance was the
key for us to be able to port libxml2. We support accessing libxml2 from
both DKMs and RTPs.

3. There are 2 compilers for VxWorks, the WindRiver compiler, and a port
of the GNU toolchain, we have only tested and built with the GNU
toolchain.

How To Build

1. Run the configure on your native linux system (this is the cheesy
hack). Since the VxWorks GNU toolchain is very close in version to the
one in red hat, it generates a good config.h file. We configured libxml2
with the following to keep the size down, (but we have done basic testing
with everything compiled in).

./configure --with-minimum --with-reader --with-writer --with-regexps
--with-threads --with-thread-alloc

2. Rename the libxml2 folder to "src". This step is required for our
replacement makefile to work.

3. Run the replacement makefile. I wrote a new makefile that sets all the
proper vxworks defines and uses the correct compilers. The two defines on
the make command line are to tell it which VxWorks Target (SH3.2 little
endian), and the executable type. We have tested this code on PENTIUM2gnu
and SH32gnule.

This makefile creates a shared library that runs on VxWorks: (libxml2.so)
make -f Makefile.vxworks clean all VXCPU=SH32gnule VXTYPE=RTP

This makefile creates a kernel module that runs on VxWorks: (xml2.out)
make -f Makefile.vxworks clean all VXCPU=SH32gnule VXTYPE=DKM

Important Notes

1. There are several ways that this process could be improved, but at the
end of the day, we make products, not port libraries, so we did a meets
minimum for our needs.

2. VxWorks is the devil, give me embedded linux every day.

3. No matter what I tried, I couldn't get the configure to pick up the
VxWorks toolchain, and in my investigation, it has something to do with
automake/autoconf, not any individual package. VxWorks doesn't play by
the normal rules for building toolchains.

4. The PIC flag in VxWorks (especially for SH processors) is very
important, and very troublesome. On linux, you can liberally use the PIC
flag when compiling and the compiler/linker will ignore it as needed, on
VxWorks if must always be on for shared libraries, and always be off for
static libraries and executables.

5. If anyone wants to work on a better way to do the build of libxml2 for
VxWorks, I'm happy to help as much as I can, but I'm not looking to
support it myself.

Attached Files

1. To use my Makefile for vxworks, you should enter the vxworks
environment (/opt/windriver/wrenv.linux -p vxworks-6.4 for me).
2. Run: build.sh libxml2-2.6.32 SH32gnule RTP (where you have
libxml2-2.6.32.tar.gz and the Makefile in the same directory as the script
file).

Thanks,

Jim Wert Jr.
JWert@ILSTechnology.com