FreeBSD 10.4 kernel breaks on i7-7700 / PRIME H270M-PLUS

[Eugene Grosbein]

On 02.04.2018 19:27, Mark Knight wrote:

>> What does it show if you press "CTRL-T" to see a status of "hung" process?
> 
> Typically CTRL-T shows [sysctl mem]. In some circumstances I can CTRL-C 
> (e.g. if su hangs), in others I cannot (e.g. with sudo).
> 
>> Does it help if you comment out the line mentioning /dev/console in the /etc/syslog.conf
>> and apply the change with killall -1 syslogd ?
> 
> Doing that "killall -HUP syslogd" hangs with (sysctl mem) - as does 
> "service syslogd restart" but after a fresh reboot, no - removing that 
> line didn't help at all. Thanks for getting my hopes up :)
> 
> Moving ~/myuser/.bashrc out of the way (it really doesn't contain much 
> apart from setting a bunch of aliases), allows me to login as myself, 
> but "sudo -u myuser -s" still hangs.
> 
> I just got a truss output of "sudo -u myuser -s" per the file below, 
> perhaps that contains a clue?
> 
> # sudo -u myuser -s >& sudo.truss.log
> 
> 	http://www.knigma.org/scratch/sudo.truss.log
> 
> Flipping back to a 10.3 kernel makes everything happy (just as well, as 
> the machine in question is my main router/firewall, so it's a right pain 
> when it's not working).
> 
> Thanks in advance for any fresh ideas; I'm really not sure where to go 
> with this!

1. Make sure you have kernel dumps enabled.
Verify that dump can be properly generated and saved after reboot
using "sysctl debug.kdb.panic=1" (this produced a panic).
You should have crashdump in /var/crash after reboot.

2. Rebuild kernel using new updated sources but this time add to its config file:

options         KDB                     # Enable kernel debugger support.
options         KDB_UNATTENDED
options         KDB_TRACE
options         DDB                     # Support DDB.
options         GDB                     # Support remote GDB.
options         INVARIANTS              # Enable calls of extra sanity checking
options         INVARIANT_SUPPORT       # Extra sanity checks of internal structures, required by INVARIANTS
options         WITNESS                 # Enable checks to detect deadlocks and cycles
options         WITNESS_SKIPSPIN        # Don't run witness on spinlocks for speed

3. Boot new kernel using nextboot(8) and see if it will crash instead of deadlock
and if so, fill the PR to Bugzilla.