Re: [Xenomai] [Xenomai-git] Jan Kiszka : boilerplate: Allow for enabling Xenomai only in shared libs

[Jan Kiszka <jan.kiszka@siemens.com>]

[please CC me on replies, I've delivery turned off for all lists]

On 2016-02-22 18:44, Gilles Chanteperdrix wrote:
> On Mon, Feb 22, 2016 at 06:40:59PM +0100, git repository hosting wrote:
>> Module: xenomai-jki
>> Branch: for-forge
>> Commit: 4601286f7fedb8267ea314584fc68d2b35b818a4
>> URL:    http://git.xenomai.org/?p=xenomai-jki.git;a=commit;h=4601286f7fedb8267ea314584fc68d2b35b818a4
>>
>> Author: Jan Kiszka <jan.kiszka@siemens.com>
>> Date:   Fri Feb  5 17:33:18 2016 +0100
>>
>> boilerplate: Allow for enabling Xenomai only in shared libs
>>
>> Normally, one builds shared libraries with Xenomai awareness by adding
>> --no-auto-init to xeno-config. This drops bootstrap.o from the linking
>> steps because - normally - the main application performs the
>> initialization.
>>
>> However, if the main application is Xenomai-free and only dlopen() would
>> pull in Xenomai services via a shared library, we face two problems:
>>
>> - bootstrap.o is not built with position-independence support
>>
>> - libboilerplate contains __real_main that expects the main symbol which
>>   cannot be found from a shared library
> 
> Does not the library find the program symbols if RTLD_GLOBAL is
> passed to dlopen?

Nope, just retried, didn't help. In fact, RTLD_GLOBAL affects only the
opened library's symbols, not the pre-existing ones. I think it is
simply not possible with dlopen to refer back to a symbol from the code
that loads the library.

Jan

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