Please test EARLY_AP_STARTUP

[John Baldwin]

On Monday, November 28, 2016 02:35:07 PM Sepherosa Ziehau wrote:
> Hi John,
> 
> fdc seems to cause panic on Hyper-V:
> https://people.freebsd.org/~sephe/fdc_panic.png

You shouldn't get this panic in latest HEAD (post-r309148).

> I then commented out device fdc, and I fixed one panic on Hyper-V here:
> https://reviews.freebsd.org/D8656

Replied to the review.

> After fdc is disabled and hyperv/storvsc is fixed, it seems to boot
> fine, except a long delay (28~30seconds) here:
> ....
> Timecounters tick every 1.000 msec
> -----
> 28 ~ 30 seconds delay
> -----
> vlan: initialized, using hash tables with chaining
> ....
> 
> I have the bootverbose dmesg here:
> https://people.freebsd.org/~sephe/dmesg_earlyap.txt
> 
> I booted 10 times, only one boot does not suffer this 30 seconds
> delay.  It sounds like some races to me.  Any hints?

It is likely a race as we start running things sooner now, yes.  Can you
break into DDB during the hang and see what thread0 is waiting on?  If
it is in the interrupt hooks you can use 'show conifhk' in DDB to see the
list of pending interrupt hooks.  That provides a list of candidate drivers
to inspect (e.g. stack traces of relevant kthreads) for what is actually
waiting (and what it is waiting on)

-- 
John Baldwin