Re: head -r338804 boots threadripper 1950X fine; head -r338810+ do not; -r338807 seems implicated

On Sun, Oct 21, 2018 at 9:28 PM Warner Losh <imp_at_bsdimp.com> wrote:

>
>
> On Sun, Oct 21, 2018 at 8:57 PM Mark Millard via freebsd-stable <
> freebsd-stable_at_freebsd.org> wrote:
>
>> [I built based on WITHOUT_ZFS= for other reasons. But,
>> after installing the build, Hyper-V based boots are
>> working.]
>>
>> On 2018-Oct-20, at 2:09 AM, Mark Millard <marklmi at yahoo.com> wrote:
>>
>> > On 2018-Oct-20, at 1:39 AM, Mark Millard <marklmi at yahoo.com> wrote:
>> >
>> >> I attempted to jump from head -r334014 to -r339076
>> >> on a threadripper 1950X board and the boot fails.
>> >> This is both native booting and under Hyper-V,
>> >> same machine and root file system in both cases.
>> >
>> > I did my investigation under Hyper-V after seeing
>> > a boot failure native.
>> >
>> > Looks like the native failure is even earlier,
>> > before db> is even possible, possibly during
>> > early loader activity.
>> >
>> > So this report is really for running under
>> > Hyper-V: -r338804 boots and -r338810 does
>> > not. By contrast -r334804 does not boot native.
>> > (But I've little information for that context.)
>> >
>> > Sorry for the confusion. I rushed the report
>> > in hopes of getting to sleep. It was not to be.
>> >
>> >> It fails just after the FreeBSD/SMP lines,
>> >> reporting "kernel trap 9 with interrupts disabled".
>> >>
>> >> It fails in pmap_force_invaldiate_cache_range at
>> >> a clflusl (%rax) instruction that produces a
>> >> "Fatal trap 9: general protection fault while
>> >> in kernel mode". cpudid=0 apic id= 00
>> >>
>> >> I used kernel.txz files from:
>> >>
>> >> https://artifact.ci.freebsd.org/snapshot/head/r*/amd64/amd64/
>> >>
>> >> to narrow the range of kernel builds for working -> failing
>> >> and got:
>> >>
>> >> -r338804 boots fine
>> >> (no amd64 kernel builds between to try)
>> >> -r338810+ fails (any that I tried, anyway)
>> >>
>> >> In that range is -r338807 :
>> >>
>> >> QUOTE
>> >> Author: kib
>> >> Date: Wed Sep 19 19:35:02 2018
>> >> New Revision: 338807
>> >> URL:
>> >> https://svnweb.freebsd.org/changeset/base/338807
>> >>
>> >>
>> >> Log:
>> >> Convert x86 cache invalidation functions to ifuncs.
>> >>
>> >> This simplifies the runtime logic and reduces the number of
>> >> runtime-constant branches.
>> >>
>> >> Reviewed by: alc, markj
>> >> Sponsored by:        The FreeBSD Foundation
>> >> Approved by: re (gjb)
>> >> Differential revision:
>> >> https://reviews.freebsd.org/D16736
>> >>
>> >> Modified:
>> >> head/sys/amd64/amd64/pmap.c
>> >> head/sys/amd64/include/pmap.h
>> >> head/sys/dev/drm2/drm_os_freebsd.c
>> >> head/sys/dev/drm2/i915/intel_ringbuffer.c
>> >> head/sys/i386/i386/pmap.c
>> >> head/sys/i386/i386/vm_machdep.c
>> >> head/sys/i386/include/pmap.h
>> >> head/sys/x86/iommu/intel_utils.c
>> >> END QUOTE
>> >>
>> >> There do seem to be changes associated with
>> >> clflush(...) use. Looking at:
>> >>
>> >>
>> https://svnweb.freebsd.org/base/head/sys/amd64/amd64/pmap.c?annotate=339432
>> >>
>> >> it appears that pmap_force_invalidate_cache_range has not
>> >> changed since -r338807.
>> >>
>> >> It seems that -r338806 and -r3388810 would be unlikely
>> >> contributors.
>> >
>>
>> I went after my native-boot loader problem first because I
>> could switch kernels via the loader for booting FreeBSD under
>> Hyper-V. Switching loaders is more of a problem.
>>
>> In order to avoid the loader-time crash I switched to building
>> installing based on WITHOUT_ZFS= . I've had no active use of
>> ZFS in years. (The old official-build loaders that worked were
>> non-ZFS ones.)
>>
>> This took care of the native-boot loader-crash --and, to my
>> surprise, also the Hyper-V-boot kernel-time crash.
>>
>> My private builds now boot the 1950X in both contexts just
>> fine.
>>
>> During my early investigation I did pick up specific changes
>> from after -r339076 that seemed to be tied to Ryzen and such.
>> (They made no difference to the boot problems at the time
>> but I saw no reason to remove them.)
>>
>> # uname -apKU
>> FreeBSD FBSDFSSD 12.0-ALPHA8 FreeBSD 12.0-ALPHA8 #5 r339076:339432M: Sun
>> Oct 21 16:44:25 PDT 2018     markmi_at_FBSDFSSD:/usr/obj/amd64_clang/amd64.amd64/usr/src/amd64.amd64/sys/GENERIC-NODBG
>> amd64 amd64 1200084 1200084
>
>
(stupid gmail)

The phrase "no active use" bothers me. What does that mean? Are there any
ZFS pools or any disks that any whiff of ZFSish thing on it at all?
Clearly, there's something in the zfs boot loader that's freaking out by
something on your system, but absent that information I can't help you.

Warner