Johan Cockx wrote:
>
>
> On Tue, Oct 12, 2010 at 12:05 PM, Gilles Chanteperdrix
> <[email protected]
> <mailto:[email protected]>> wrote:
>
> Johan Cockx wrote:
> >
> >
> > On Mon, Oct 11, 2010 at 4:07 PM, Gilles Chanteperdrix
> > <[email protected]
> <mailto:[email protected]>
> > <mailto:[email protected]
> <mailto:[email protected]>>> 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.
>
>
> > > Attached is a small stand-alone test case. It consists of two
> > programs:
> > > recv.c will wait for a udp message with a timeout of 10 sec
> (using
> > > select), and send.c will send a udp message. If recv is started
> > and then
> > > send (in another terminal), recv should return immediatly
> without
> > > timeout; however, it continues to wait until a timeout occurs.
> >
> > By standalone, I meant without RTnet. So, please verify that
> you also
> > get the bug without RTnet, and post a mail to the Xenomai-help
> mailing
> > list (as opposed to the rtnet mailing list, which is the
> mailing list
> > where you are posting currently).
> >
> >
> > I am not sure how to test the bug with Xenomai but without RTnet. If I
> > replace --posix-cflags and --posix-ldflags by --xeno-flags and
> > --xeno-ldflags and use a plain (non-rt) IP address, there is no
> problem.
>
> Try posix message queues.
>
> Sorry, not clear to me: how can I reproduce a bug related to UDP
> messages with posix message queues?
The point is to know whether it is a generic select bug or an UDP socket
bug. If it happens with posix message queues, it is a select bug. If it
happens only with UDP sockets, then it is related to UDP sockets somehow.
--
Gilles.
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