Re: [Xenomai-help] Shared memory and fstat()

[Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>]

Herrera-Bendezu, Luis wrote:
> Hello,
> 
> Can a file descriptor returned from Xenomai POSIX skin
> shm_open()/ftruncate() used in fstat()?

No.

> 
> Value returned for st_size in the stat structure is
> always 0 despite change of size using ftruncate().
> 
> Noticed that shared memory object does not have an entry
> on /dev/shm as regular POSIX objects. Where is it located?
> If entry exists, can it be used to query its size?

No, xenomai posix skin shared memory do not exist as filesystem objects,
they will only be listed in /proc/xenomai/heap.

Note, however, that they are only useful for sharing memory between
kernel-space posix applications and user-space posix applications, which
should have become rare these days. If what you are looking for is
simply a way for sharing memory between to user-space real-time
applications, they you can use linux regular shared memories, for which
fstat works.

> 
> Thanks,
> Luis
> 
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-- 
					    Gilles.