Help diagnose my Ryzen build problem

[Gary Jennejohn]

On Mon, 27 Aug 2018 16:16:47 +0300
"karu.pruun" <karu.pruun at gmail.com> wrote:

> On Mon, Aug 27, 2018 at 3:21 PM Meowthink <meowthink at gmail.com> wrote:
> > That's kib, who has committed things in that script to both 12 [1] and
> > stable/11 [2].
> >
> > Unfortunately, that's for Ryzens family 17h model 00h-0fh, whereas my
> > Ryzen 5 2400G's model is 11h.
> >
> > On the microcode. It shall be updated through UEFI/BIOS updates. I
> > think mine is now PinnaclePI-AM4_1.0.0.4 with microcode patchlevel
> > 0x810100b.
> >
> > Seems like ... the only thing I can do is sit down and wait?  
> 
> The revision
> 
> https://svnweb.freebsd.org/base/head/sys/x86/x86/cpu_machdep.c?r1=336763&r2=336762&pathrev=336763
> 
> works around the mwait issue, i.e. it sets
> 
> sysctl machdep.idle_mwait=0
> sysctl machdep.idle=hlt
> 
> Now it may or may not relate to your problem, but it appears that
> Ryzen 2400G also has another issue with HLT, see the DragonFly bug
> report
> 
> https://bugs.dragonflybsd.org/issues/3131
> 
> which AMD is aware of and is possibly working on, but it may not have
> appeared in the errata yet. The bug report says that until this is
> fixed, the workaround is to also disable HLT in cpu_idle. I am not
> sure what is the correct value for the sysctl on FreeBSD, perhaps
> 
> sysctl machdep.idle=0
> 
> or some other value?
> 

It is in the latest errata and there are no plans to fix it.

Based on the detailed description, this is a problem only in a
hypervisor.  AMD has a suggested workaround for it.

-- 
Gary Jennejohn