first off, for kernel-based realtime (rtai), this is not possible at all. second, assuming you are going to call into this shared library from uspace in a realtime context, you will need to audit the library source code to make sure it is not making any API calls that are not OK for realtime.
All that said: This is technically possible for uspace realtime but is not currently facilitated by halcompile or "Makefile.modinc" which is a Makefile fragment that it uses to actually do the work of building a .so realtime component. I will be happy to review patches to improve/fix this. Basically, it would be necessary to: * change Makefile.modinc.in so that it can supply extra linker arguments under the "%.so:" rule near where -lm is currently hard-coded (src/Makefile.modinc.in) We use some trickery regarding symbol visibility in .so realtime components, so that the EXPORT_SYMBOL directives are obeyed. Right now the trick used in Makefile is newer and probably better than the one in Makefile.modinc.in. I'm not sure whether either trick affects the ability to link in other libraries, but the newer trick is more like the normal way shared library symbol visibility is managed on Linux. We should probably update Makefile.modinc.in to use the new trick, particularly if the old trick causes problems with additional shared libraries * change halcompile so that it can receive these extra arguments as commandline arguments and pass them on to make via the commandline (src/hal/utils/halcompile.g). If it's feasible, halcompile should also refuse to accept the arguments if the realtime is not uspace. * document these features in the manual (docs/man/man1/halcompile.1, docs/src/hal/comp.txt) * and write a new test under tests/halcompile/ that shows these features work. Please be aware of our policy to use Linux Kernel-style Signed-Off-By http://linuxcnc.org/docs/2.7/html/code/contributing-to-linuxcnc.html#_signed_off_by_policy You can use several methods, such as a github pull request, to share your patches for review: http://linuxcnc.org/docs/2.7/html/code/contributing-to-linuxcnc.html#_linuxcnc_on_github Jeff ------------------------------------------------------------------------------ Site24x7 APM Insight: Get Deep Visibility into Application Performance APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month Monitor end-to-end web transactions and take corrective actions now Troubleshoot faster and improve end-user experience. Signup Now! http://pubads.g.doubleclick.net/gampad/clk?id=272487151&iu=/4140 _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
