[xml] libxml2 on VxWorks 6.4+

[jwert ilstechnology com]

Daniel,

<Resent with better Subject>

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

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