enabling kernel dump options in GENERIC

[Mark Millard]

On 2018-May-17, at 11:17 PM, Mark Johnston <markj at FreeBSD.org> wrote:

> On Thu, May 17, 2018 at 08:58:16PM -0700, Mark Millard wrote:
>> Mark Johnston markj at FreeBSD.org wrote on
>> Thu May 17 17:24:19 UTC 2018 :
>> 
>>> Over the past couple of years, a number of kernel dump features have
>>> been added: encryption, compression and dumping to a remote host
>>> (netdump). These features are currently all omitted from GENERIC.
>>> 
>>> . . .
>>> Therefore, I'd like to propose enabling these features by default
>>> on i386, amd64, arm64, powerpc(64) and sparc64 so that they're available
>>> out of the box in 12.0.
>>> . . .
>> 
>> Bugzilla 214598 (from late 2016) was about
>> dump for TARGET_ARCH=powerpc64 builds getting
>> failures like:
>> 
>> KDB: enter: manual escape to debugger
>> [ thread pid 12 tid 10018 ]
>> Stopped at       .kdb_enter+0x70:       ori r0, r0, 0x0
>> db> dump
>> Dumping 9 MB (3 chunks)
>>  chunk 0: 10MB (2510 pages) ... ok
>>  chunk 1: 1MB (24 pages) ... ok
>>  chunk 2: 1MB (2 pages)panic: vm_fault: fault on nofault entry, addr: c000000000022000
>> 
>> (A 32-bit powerpc build on the same machine worked
>> fine for dumping.)
>> 
>> I just tried it with head -r333594 and I got something
>> similar. (Old and new mention routines with _bus_dma_map_
>> in the names near the trap in the call stack. I've not
>> done a detailed comparison.)
> 
> What is the call stack?

I'll have to induce the failure, take a picture of
the screen that results, and hand type in the
material for the fairly modern backtrace (-r333594).
I will not be able to do this until later today.

The bugzilla report has the old backtrace. I did not
quote all the material from that report in the above.
So there is something to compare against once I
supply a modern one.

Also: in about a week I'll lose access to the PowerMacs
for an unknown period of time (weeks? months?).

===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)