Re: EARLY_AP_STARTUP hangs during boot

On Tuesday, June 07, 2016 12:06:54 PM Gary Jennejohn wrote:
> On Tue, 31 May 2016 13:10:06 -0700
> John Baldwin <jhb_at_freebsd.org> wrote:
> 
> > On Saturday, May 28, 2016 02:11:41 PM Gary Jennejohn wrote:
> > > On Fri, 27 May 2016 09:50:05 +0200
> > > Gary Jennejohn <gljennjohn_at_gmail.com> wrote:
> > >   
> > > > On Thu, 26 May 2016 16:54:35 -0700
> > > > John Baldwin <jhb_at_freebsd.org> wrote:
> > > >   
> > > > > On Tuesday, May 17, 2016 06:47:41 PM Gary Jennejohn wrote:    
> > > > > > On Mon, 16 May 2016 10:54:19 -0700
> > > > > > John Baldwin <jhb_at_freebsd.org> wrote:
> > > > > >       
> > > > > > > On Monday, May 16, 2016 12:22:42 PM Gary Jennejohn wrote:      
> > > > > > > > I tried out EARLY_AP_STARTUP, but the kernel hangs and I can't
> > > > > > > > break into DDB.
> > > > > > > > 
> > > > > > > > I did a verbose boot and the last lines I see are related to routing
> > > > > > > > MSI-X to various local APIC vectors.  I copied the last few lines and
> > > > > > > > they look like this:
> > > > > > > > 
> > > > > > > > msi: routing MSI-X IRQ 256 to local APIC 2 vector 48
> > > > > > > > msi: routing MSI-X IRQ 257 to local APIC 3 vector 48
> > > > > > > > msi: routing MSI-X IRQ 258 to local APIC 4 vector 48
> > > > > > > > msi: routing MSI-X IRQ 256 to local APIC 0 vector 49      
> > > > > >          ^^^^^^^ Assigning      
> > > > > > > > 
> > > > > > > > I tried disabling msi and msix in /boot/loader.conf, but the settings
> > > > > > > > were ignored (probabaly too early).        
> > > > > > > 
> > > > > > > No, those settings are not too early.  However, the routing to different
> > > > > > > CPUs now happens earlier than it used to.  What is the line before the
> > > > > > > MSI lines?  You can take a picture with your phone/camera if that's simplest.
> > > > > > >       
> > > > > > 
> > > > > > Here a few lines before the MSI routing happens:
> > > > > > 
> > > > > > hpet0: <High Precision Event Timer> iomem 0xfed00000-0xfed003ff irq 0,8 on acpi0
> > > > > > hpet0: vendor 0x4353, rev 0x1, 14318180 Hz, 3 timers, legacy route
> > > > > > hpet0: t0 : irqs 0x00c0ff (0), MSI, periodic
> > > > > > hpet0: t1 : irqs 0x00c0ff (0), MSI, periodic
> > > > > > hpet0: t2 : irqs 0x00c0ff (0), MSI, periodic
> > > > > > Timecounter "HPET" frequency 14318180 Hz quality 950      
> > > > > 
> > > > > The assigning message means it is in the loop using
> > > > > bus_bind_intr() to setup per-CPU timers.  Can you please try
> > > > > setting 'hint.hpet.0.per_cpu=0' at the loader prompt to see if
> > > > > disabling the use of per-CPU timers allows you to boot?
> > > > >     
> > > > 
> > > > Something has changed since the last time I generated a kernel with
> > > > this option.
> > > > 
> > > > Now I get a NULL-pointer dereference in the kernel, doesn't matter
> > > > whether I set the hint or not.
> > > >   
> > > 
> > > OK, now that the startup has been fixed, I tried setting the hint at
> > > the loader prompt, but the kenel hangs in exactly the same place as
> > > before.  I actually booted twice to make certain I hadn't made a
> > > typo when setting the hint.  
> > 
> > Humm, it shouldn't be calling bus_bind_intr() if the hint is set.  Actually,
> > I guess it just binds them all to first CPU if per-CPU timers aren't set.
> > Can you add debug printfs to hpet_attach() in sys/dev/acpica/acpi_hpet.c to
> > narrow down which line in that function it hangs after?
> > 
> > Another option to try is to add the following to your kernel config:
> > 
> > options  	KTR
> > options  	KTR_COMPILE=KTR_PROC
> > options 		KTR_MASK=KTR_PROC
> > options  	KTR_VERBOSE=1
> > 
> > this will spew a lot of crap to the screen, but if it stops spewing when it
> > hangs then it might be tell us where the system is hung.  If you have any way
> > to configure a serial console then this would also be useful even if it spews
> > constantly when it is hung (assuming you could log the output of the serial
> > console).
> > 
> 
> I used the KTR options.
> 
> After the Timecounter "HPET" frequency 14318180 Hz quality 950 I see
> 
> cpu0 mi_switch: old thread 10000 (swapper)
> cpu0 mi_switch: new thread 10022 (if_config_tqg_0)
> cpu0 sleep_broadcast(0x80002f9a600, 0)
> cpu0 msleep_spin: old thread 100022
> cpu0 mi_switch: old thread 10022
> cpu0 mi_switch: new thread 10016 (if_io_tqg_0)
> cpu0 sleep_broadcast(0x80002f9a780, 0)
> cpu0 msleep_spin: old thread 10016
> cpu0 mi_switch: old thread 10016
> cpu0 fork_exit: new thread 0x80004239510 (td_sched 0x8000042399d8, pid
> 10, idle: cpu0)
> 
> And that's all that came out, really not very much at all.

Ok, that seems odd.

Can you apply this patch and run with the KTR output still:

Index: sched_ule.c
===================================================================
--- sched_ule.c	(revision 303397)
+++ sched_ule.c	(working copy)
_at__at_ -1904,6 +1904,13 _at__at_ sched_switch(struct thread *td, struct thread *new
 	td->td_owepreempt = 0;
 	if (!TD_IS_IDLETHREAD(td))
 		tdq->tdq_switchcnt++;
+
+	if (td == &thread0 && cold) {
+		printf("thread0 switching out (ts_cpu %d):\n", ts->ts_cpu);
+		kdb_backtrace();
+		MPASS(TD_IS_RUNNING(td));
+	}
+	
 	/*
 	 * The lock pointer in an idle thread should never change.  Reset it
 	 * to CAN_RUN as well.
_at__at_ -1920,6 +1927,9 _at__at_ sched_switch(struct thread *td, struct thread *new
 		if (THREAD_CAN_MIGRATE(td) && !THREAD_CAN_SCHED(td, ts->ts_cpu))
 			ts->ts_cpu = sched_pickcpu(td, 0);
 #endif
+		if (td == &thread0 && cold)
+			printf("thread0 ts_cpu %d, cpuid %d\n", ts->ts_cpu,
+			    cpuid);
 		if (ts->ts_cpu == cpuid)
 			tdq_runq_add(tdq, td, srqflag);
 		else {


-- 
John Baldwin