[Xenomai-core] Re: [Xenomai-help] Panic in rt_queue_create: bug or misuse?

[Philippe Gerum <rpm@xenomai.org>]

Jan Kiszka wrote:
> Brian L. wrote:
> 
>>How could I forget mlockall? I've been calling it in rtai forever...Is
>>there any other neccessary boilerplate?
> 
> 
> This is a very frequently made mistake. Philippe, is there a chance add
> some simple debug check for this situation? Something to check when the
> first shadow thread is created for a process?

The following patch would cause SIGXCPU to be sent to emerging real-time 
threads from a non-fully mlocked program (i.e. not including 
MCL_FUTURE). We should make this conditionally compiled too. I'm not 
sure that we would not introduce problems when dealing with mmio areas 
mapped in user-space at least for older kernel revisions (the VM_IO 
issue might have been fixed in recent kernels, though), this is why I 
would tend to make it easy to work around this check by simply ignoring 
the signal, for handling specific init configurations for which people 
know what they are doing.

--- ksrc/nucleus/shadow.c	(revision 875)
+++ ksrc/nucleus/shadow.c	(working copy)
@@ -754,6 +754,9 @@
  		    current->pid,
  		    xnthread_base_priority(thread));

+    if (!(current->mm->def_flags & VM_LOCKED))
+	send_sig(SIGXCPU,current,1);
+
      current->cap_effective |=
  	CAP_TO_MASK(CAP_IPC_LOCK)|
  	CAP_TO_MASK(CAP_SYS_RAWIO)|

-- 

Philippe.