Re: [Xenomai-help] Some problems with shared memory

[Philippe Gerum <rpm@xenomai.org>]

On Mon, 2009-06-08 at 10:25 +0200, roderik.wildenburg@domain.hid
wrote:
> > 
> > roderik.wildenburg@domain.hid wrote:
> > >> All I want to hear is "yes, we ran the shm test without Xenomai, on
> > >> exactly the same kernel, on the same platform, and the shm 
> > >> test worked".
> > >> Because Xenomai runs plain Linux mmap under the hood and do no
> > >> particular check on the mmap length. So, the problem is either that
> > >> Linux mmap on that particular machine with that particular 
> > >> kernel does a
> > >> check on length, or that there is a subtle bug somewhere 
> > that I do not
> > >> want to investigate until I am usre that it is real.
> > > 
> > > 
> > > yes, we ran the shm test without Xenomai, on
> > > exactly the same kernel, on the same platform, and the shm 
> > > test worked.
> > > 
> > > This means : 
> > > I took a plain 2.4.25 PPC-Kernel and started killtest 
> > without pagealigned shm size and got the error message :
> > > shm_open fails. errno=38 SHM:/testshm
> > > shm_open: Function not implemented
> > > 
> > > Therefore I mounted a tmpfs on /dev/shm and killtest ran 
> > without any errormessage.
> > > To make shure the missing /dev/shm isn´t the reason for the 
> > mmap-error I took a xenomai-enhanced kernel, mounted /dev/shm 
> > and run (a xenomai-linked) killtest, but I still got the error :
> > > killtest2 # ./killtest -c
> > > createshm mmap: No such device or address
> > > shmsize = 100000; errno : 6 == Failed to create shm : -3
> > > killtest user exit !
> > > 
> > > This I tried with Xenomai 2.3.5 and 2.4.7 (and got the same error).
> > > Even on a Xenomai-enhanced kernel a killtest, which was 
> > linked without Xenomai-libraries, run without error.
> > > 
> > > Sorry for not having better news
> > > Roderik
> 
> 
> 
> > Hi,
> > 
> > this should have been fixed in the 2.4.8 release, so please 
> > test it and
> > tell us whether it works for you.
> > 
> 
> Hello,
> 
> sorry for the delayed answer.
> Yes and no: The restriction of a page aligned SHM-size seems to be abolished (I didn´t get the error message "No such device or address" any more).
> But my target still stalls, when I kill my test applications in the wrong order.
> For your convenience I appended the test again (start "killtest -c &" then "killtest &" and then kill the last one before the first).
> 

By "stalls", do you mean a lockup, or does your shell hang upon ^C while
the rest of the system keeps running fine?

> Best regards
> Roderik
> 
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-- 
Philippe.