Re: [PATCH] Add build time guard to detect off_t mismatch

On Tue, 2026-05-12 at 17:04 +0200, Richard Weinberger wrote:
> On Tue, May 12, 2026 at 4:26 PM Florian Bezdeka
> <[email protected]> wrote:
> > __RT() might be the problem here. You will end up in __cobalt_mmap()
> > unconditionally, right? Does migrating to mmap() with all the wrapping
> > magic help here?
> 
> When not using __RT(), the unresolved symbol is  __wrap_mmap64().

I'm still confused about the missing __wrap symbol, but to repair __RT()
for mmap() we have to do something similar as glibc does:

#ifndef __USE_FILE_OFFSET64
extern void *mmap (void *__addr, size_t __len, int __prot,
		   int __flags, int __fd, __off_t __offset) __THROW;
#else
# ifdef __REDIRECT_NTH
extern void * __REDIRECT_NTH (mmap,
			      (void *__addr, size_t __len, int __prot,
			       int __flags, int __fd, __off64_t
__offset),
			      mmap64);
# else
#  define mmap mmap64
# endif
#endif

The redirect part is most likely missing in Xenomai. Redirect mmap() to
mmap64() in case 64bit offsets are in use.

> 
> > Probably the same question as we had for the time_t related services: Do
> > we want one libcobalt build to support both worlds at the same time?
> 
> At least the application on my desk uses __RT() a lot.
> Sorting all this out would make some pople rather unhappy, I guess.
> 
> -- 
> Thanks,
> //richard