Brian,

Thanks for the help.  I believe I will go ahead and just have a separate
install that sets the -m32 compile flag
as part of the default.

Since you asked, the scenario here is that I have several ROS nodes running
on a 64 bit machine and
a third party library(for which I don't have access to the code) for one of
the nodes only has a 32-bit version(currently).
My hope is they will provide me with a 64-bit version soon, but in the
meantime, I still need to move forward,
which I will by setting up a seperate ros build for the 32-bit package.

Thanks,

Jeff Hyams
RE2, Inc.
www.resquared.com



On Mon, Jun 14, 2010 at 12:29 PM, Brian Gerkey <gerkey@willowgarage.com>wrote:

> hi Jeff,
>
> On Mon, Jun 14, 2010 at 6:24 AM, Jeff Hyams <jeff.hyams@resquared.com>
> wrote:
> > I am trying to get ROS to compile with 32 bit (-m32) libraries on an 64
> bit
> > kernel.  I am wondering two things
> > about the build:
> >
> > 1.  Is there a way in one of my nodes to "inject" the -m32 compile option
> to
> > all dependent packages when building my package? Or will
> >      I need to edit each individual package's CMake files to get the -m32
> > option in there?
>
> The build system allows you to specify default compile and link flags
> to be passed to all packages:
>
> http://www.ros.org/wiki/rosbuild#Customizing_the_build_.28debug.2C_optimizations.2C_default_build_flags.29
> .  For example, if you want to add "-m32" to all compile and link
> steps for all packages, you could put these lines in
> $ROS_ROOT/rosconfig.cmake (manually prepending the default values from
> rosbuild/rosconfig.cmake):
>  set(ROS_COMPILE_FLAGS "-W -Wall -Wno-unused-parameter
> -fno-strict-aliasing -pthread -m32")
>  set(ROS_LINK_FLAGS "-pthread -m32")
>
> Alternatively, if you want only packages that depend on package 'foo'
> to be built with certain flags, you can export them from
> foo/manifest.xml, e.g.:
>  <export>
>    <cpp cflags="-m32" lflags="-m32"/>
>  </export>
> Note that this mechanism does *not* allow you to specify build flags
> for packages on which 'foo' depends.  Package dependency is one-way.
>
> > 2.  I think the answer to the following is that it I'd have to do it
> myself,
> > but I'll ask anyways:
> >        I need to still compile 64 bit ROS packages as well as my single
> 32
> > bit package.  Is there a method in the build system already to allow
> >        both 32 bit and 64-bit compiled libraries to exist in a single ROS
> > home?
>
> No, there is no support for building libraries (or executables) in
> both 32-bit and 64-bit.  There is support for building them both
> statically-linked and dynamically-linked.
>
> > 2a.  If the answer to the above is no(which I suspect it is after cursory
> > examination), would the easiest option be to add a
> >        separate ROS install, get it to compile all the libraries as 32
> > bit(with whatever the answer to #1 would be), then use
> >        that install to compile my package?  I don't have a ton of time to
> > modify the build structure to allow both libraries to
> >        exist at the moment, so I'm looking for a quick and easy solution.
>
> I don't fully understand your use case, but I suspect that the answer
> here is yes.
>
>        brian.
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