On Thu, Jan 28, 2021 at 03:02:39AM +0000, Stuart Henderson wrote:
> On 2021/01/28 12:21, Jonathan Gray wrote:
> > > NMI ... going to debugger
> > > Stopped at tsc_delay+0x63: lfence
> > > ddb{0}> trace
> > > tsc_delay(1) at tsc_delay+0x63
> > > r100_ring_test(ffff8000001a4000,ffff8000001a5858) at r100_ring_test+0x277
> > > r100_cp_init(ffff8000001a4000,100000) at r100_cp_init+0x5a1
> > > r100_startup(ffff8000001a4000) at r100_startup+0x535
> > > r100_init(ffff8000001a4000) at r100_init+0x4ac
> > > radeon_device_init(ffff8000001a4000,ffff800000196800,ffff800000196840,840001)
> > > a
> > > t radeon_device_init+0x944
> > > radeondrm_attachhook(ffff8000001a4000) at radeondrm_attachhook+0x36
> > > config_process_deferred_mountroot() at
> > > config_process_deferred_mountroot+0x6b
> > > main(0) at main+0x723
> > > end trace frame: 0x0, count: -9
> >
> > I don't understand why an lfence would cause an nmi.
>
> I was thinking that it might not be the lfence triggering it but
> something that happened just before connected with the video init,
> and it's just that the tsc_delay/lfence is what's running when it hit ..
right, as cheloha noted the other trace points at rdtsc.
>
> > Does it still occur with the below diff to change lfence;rdtsc to rdtscp?
> > This requires RDTSCP which your machine has but bluhm's machine does not.
> >
> > Perhaps it is related to some kind of watchdog timer? Can you check if
> > the ilo event log has any relevant information?
> >
> > Index: sys/arch/amd64/include/cpufunc.h
> > ===================================================================
> > RCS file: /cvs/src/sys/arch/amd64/include/cpufunc.h,v
> > retrieving revision 1.36
> > diff -u -p -r1.36 cpufunc.h
> > --- sys/arch/amd64/include/cpufunc.h 13 Sep 2020 11:53:16 -0000
> > 1.36
> > +++ sys/arch/amd64/include/cpufunc.h 28 Jan 2021 00:47:16 -0000
> > @@ -307,7 +307,8 @@ rdtsc_lfence(void)
> > {
> > uint32_t hi, lo;
> >
> > - __asm volatile("lfence; rdtsc" : "=d" (hi), "=a" (lo));
> > +// __asm volatile("lfence; rdtsc" : "=d" (hi), "=a" (lo));
> > + __asm volatile("rdtscp" : "=d" (hi), "=a" (lo) :: "ecx");
> > return (((uint64_t)hi << 32) | (uint64_t) lo);
> > }
> >
> >
>
>
