On Tue, Oct 12, 2010 at 3:04 PM, Gilles Chanteperdrix <
gilles.chanteperd...@xenomai.org> wrote:
> Johan Cockx wrote:
> >
> >
> > On Tue, Oct 12, 2010 at 12:32 PM, Gilles Chanteperdrix
> > <gilles.chanteperd...@xenomai.org
> > <mailto:gilles.chanteperd...@xenomai.org>> wrote:
> >
> > Johan Cockx wrote:
> > >
> > >
> > > On Tue, Oct 12, 2010 at 12:05 PM, Gilles Chanteperdrix
> > > <gilles.chanteperd...@xenomai.org
> > <mailto:gilles.chanteperd...@xenomai.org>
> > > <mailto:gilles.chanteperd...@xenomai.org
> > <mailto:gilles.chanteperd...@xenomai.org>>> wrote:
> > >
> > > Johan Cockx wrote:
> > > >
> > > >
> > > > On Mon, Oct 11, 2010 at 4:07 PM, Gilles Chanteperdrix
> > > > <gilles.chanteperd...@xenomai.org
> > <mailto:gilles.chanteperd...@xenomai.org>
> > > <mailto:gilles.chanteperd...@xenomai.org
> > <mailto:gilles.chanteperd...@xenomai.org>>
> > > > <mailto:gilles.chanteperd...@xenomai.org
> > <mailto:gilles.chanteperd...@xenomai.org>
> > > <mailto:gilles.chanteperd...@xenomai.org
> > <mailto:gilles.chanteperd...@xenomai.org>>>> wrote:
> > > >
> > > > Johan Cockx wrote:
> > > > > A printf in src/skins/posix/select.c confirms that
> > __wrap_select
> > > > is called.
> > > >
> > > > Ok, but there are many branches here, could you check
> > whether
> > > it emits
> > > > the syscall, and if yes, what is the result of this
> syscall?
> > > >
> > > >
> > > > First, it executes:
> > > > err = XENOMAI_SKINCALL5(__pse51_muxid, __pse51_select,
> > __nfds,
> > > > __readfds, __writefds, __exceptfds,
> __timeout);
> > > > (which expands to assembly code; is this the syscall you are
> > > referring to?)
> > > >
> > > > This returns err == -9 ( == -EBADF), so it continues to call
> > > > __real_select (which as far as I understand it calls the
> plain
> > > > non-xenomai select) which returns 0 (timeout).
> > > >
> > > > EBADF suggests that there is something wrong with the file
> > descriptor,
> > > > but I have no clue what. The code that creates this file
> > > descriptor was
> > > > attached to my previous mail (recv.c).
> > >
> > > It means that one of the file descriptors you pass to select
> > is not a
> > > Xenomai file descriptor.
> > >
> > >
> > > Ok, but the one file descriptor that I am passing in was created
> > with a
> > > socket() call, and since I am using the posix skin, I assume it
> > should
> > > be a Xenomai file descriptor. Is there any way that the socket()
> call
> > > (using the posix skin) could return a non-Xenomai file descriptor?
> >
> > Yes, if it ends up calling __real_socket instead of socket. You can
> > instrument the __wrap_socket code, the same way you did with
> > __wrap_select, to see what happens.
> >
> >
> > Ok: __real_socket is not called, the XENOMAI_SKINCALL3(...) code
> > returns zero in this case.
>
> Ok. zero should be translated in something like 1024 - 128. And the
> reverse operation happen in select code.
>
If I understand you correctly, the socket call is returning a valid Xenomai
file descriptor as it should. So, the next question is: why is this file
descriptor (or the corresponding mask) not recognized as such in select()?
Do you have any further suggestions on how to debug this?
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