Re: [Xenomai] Order options to build a Xenomai program

[Per Oberg <pero@wolfram.com>]

----- Den 13 sep 2018, på kl 23:36, Leopold Palomo-Avellaneda leo@alaxarxa.net skrev:

> Hi,

> El 13/09/18 a les 14:42, Lange Norbert ha escrit:

>> link order is important and goes left-to-right, this seems to include
> > "wrappers",
>> which only wrap symbols that where already encountered (to the left of the
> > wrapper argument)

> [...]

>> The call to malloc is wrapped to __wrap_malloc and __real_malloc is wrapped to
> > malloc,
> > since there is no object file yet, this does nothing.
>> libmodechk exports __wrap_malloc and __real_malloc, yet no one cares and
> > --as-needed
> > will remove it as dependency
> > The app objects depend on malloc.

> > I am not sure where your dependency to __real_malloc comes from, but I suppose
>> It's from the bootstrap code, which would be needed to be linked before the
> > wrapper.
> > Probably weak dependencies further complicate things.

> I think that you got the point!!

> So, from my point of view it confirm my suspicious that the wrapper
> mechanism is fragile. I really didn't understand why Xenomai core team
> changed the native API for the POSIX. Although I saw the Jan Kiska
> conference video explaining it, tell me primitive or dump, but I prefer
> to have a RT API that links against RT libraries and you can mix the
> POSIX functions that you want in a clear way.

> OTOH I have to admit that convert a POSIX program to RT in an easy way
> is amazing.


This! 

Being able to use the same code, without patches or a lot of defines including other files is a very clean way of debugging your software. I often set up Simulations where I use my laptop running or our controller, possibly connected to remote hardware to debug stuff. For these cases  the POSIX skin is very useful.

> > As noted by Henning, please look at https://github.com/nolange/cmake_xenomai,
> > could use some feedback =).
> > Particularly look at the patchset which also removes some headaches with linking
> > precompiled object file for bootstrapping (but needs some upstream changes).

> Norbert, I have followed your emails and your project. You did a good
> job, but I don't agree with your approach. My points are:

> - You are trying to convert Xenomai a CMake project and this probably
> will not happen because Upstream is very happy with the autotools. I
> don't like to touch anything from upstream. Maybe some patch, but
> incorporated in Upstream.

What do you mean with "convert Xenomai a CMake project"? I feel that I am missing something...

Is it simply that  the "xeno-config" way of doing things isn't cmak-onic enough for a "real" CMake project or is there something deeper?

> - I would prefer follow the Upstream guidelines that recommends use
> xeno-config to obtain the needed parameters to build your application.
> So, any build tool should use xeno-config (maintained by upstream) that
> provide the correct flags or whatever to build your application.

> - I agree with Norbert that bootstraped code is not a good idea. But
> this change should be done by upstream. But if I'm not wrong, Phillipe
> said that it hasn't an easy solution.

> But for the curious, I have done this example:

> https://github.com/iocroblab/xenomai-cmake

> but it's not polished and had some mistakes. The idea is to use any
> Xenomai installation without touched and then use CMake to build your
> application.

> Cheers,

> Leopold

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Thanks,
Per Öberg