Re: 2.6.13-rc6-rt9

["Paul E. McKenney" <paulmck@us.ibm.com>]

On Thu, Sep 29, 2005 at 09:54:23AM +0200, Peter Zijlstra wrote:
> On Sat, 2005-08-20 at 17:24 -0400, Jeff Dike wrote:
> > On Sat, Aug 20, 2005 at 09:27:25PM +0200, Peter Zijlstra wrote:
> > > Jeff, could you help us out here?
> > > What exactly does uml need to get out of the calibrate delay loop?
> > 
> > Interrupts, it's not too demanding :-)
> > 
> > If it's not seeing VTALRM, then it will never leave the calibration loop.
> > 
> > Try stracing it and see what it's getting.
> 
> Sorry for the late reply.
> 
> Yes, that does seem to be the problem.
> 
> Even with a current -rt (2.6.14-rc2-rt5) UML does not run. The issue is
> indeed (as jeff pointed out) that VTALRM is never send. The small test
> programm below illustrates this.
> 
> On a non-rt kernel it completed in 1 second.
> On a -rt kernel it waits at infinitum.

Will play with it and see what I broke...

							Thanx, Paul

> Kind regards,
> 
> Peter Zijlstra
> 
> ---------------------------
> 
> #include <stdio.h>
> #include <stdlib.h>
> #include <unistd.h>
> #include <sys/time.h>
> #include <signal.h>
> 
> volatile int quit = 0;
> 
> void sig_vtalrm(int signr, siginfo_t * si, void * arg)
> {
>         if (signr == SIGVTALRM) quit = 1;
> }
> 
> int main()
> {
>         struct itimerval ival = {{0,0}, {1, 0}};
> 
>         struct sigaction sa;
>         sa.sa_sigaction = sig_vtalrm;
>         sigemptyset(&sa.sa_mask);
>         sa.sa_flags = 0;
>         sigaction(SIGVTALRM, &sa, NULL);
> 
>         setitimer(ITIMER_VIRTUAL, &ival, NULL);
> 
>         printf("wait\n");
>         while (!quit) ;
>         printf("done\n");
> }
> 
> 
> -- 
> Peter Zijlstra <a.p.zijlstra@chello.nl>
> 
>