Failed attempt to boot a (non-debug) head -r339076 on an old PowerMac G5 "Quad Core" (built via devel/powerpc64-gcc): Waking up CPU 1

[Mark Millard]

On 2018-Oct-9, at 8:20 AM, Mark Millard <marklmi at yahoo.com> wrote:

> [The stable/head mix seems to be a wrong idea: 11.2 gets past
> the SMP: messages just fine on the so-called G5 "Quad Core".]
> 
> On 2018-Oct-8, at 5:14 PM, Mark Millard <marklmi at yahoo.com> wrote:
> 
>> On 2018-Oct-8, at 1:27 PM, Justin Hibbits <chmeeedalf at gmail.com> wrote:
>> 
>>>> . . .
>>> 
>>> It would be helpful to know the last known-good SVN revision, both for
>>> Head and 11.x, as well as the oldest failing one.  Since my G5 bit the
>>> dust, I can't check locally.
>> 
> . . .

There are examples of head's kernels that sometimes
fail to get to the "SMP:" messages and sometimes work
for getting there (and beyond). So:

My reporting any example failure is a solid indicator
of the "does not reach "SMP:" problem in that build.
(All tries reached the waking message on at least cpu
1.)

My reporting "worked" for a revision might be a
misclassification. (This makes for a messier
"binary-like search".)

That said, the summary of the later detail is:

head -r334494 kernel worked
head -r334528 kernel failed

(There is nothing between those for:

https://artifact.ci.freebsd.org/snapshot/head/r*/powerpc/powerpc64/kernel.txz

so getting a smaller range requires builds.
I've not attempted that.)

The only machine-dependent powerpc64 change between
those 2 that I see is:

Author: jhibbits
Date: Fri Jun  1 21:37:20 2018
New Revision: 334498
URL: 
https://svnweb.freebsd.org/changeset/base/334498


Log:
  Increase powerpc64 KVA from ~7.25GB to 32GB
. . .




More detail for the test sequence follows, if you care.
Otherwise skip it.

The following was complicated by the discovery that
for some(?) kernels, a kernel that worked one time
could in a later try fail. (It is almost like it is
using some uninitialized RAM and getting
varying behavior, possibly depending on
unload->load sequences in the loader.)

I noticed because of using unload and load after
a failure to (try) boot a previously working
kernel to set up the next test.

Stated based on:
head -r333594 kernel always has worked
head -r339076 kernel failed

Searching:

head -r336706 kernel failed
head -r335006 kernel sometimes worked, later: sometimes failed
head -r335852 kernel sometimes worked, later: sometimes failed
<various failed's not shown here,
  given the above 2 later "sometimes fails" discoveries>

head -r334298 kernel worked
head -r334644 kernel failed
head -r334474 kernel worked
head -r334554 kernel sometimes worked, later: sometimes failed
head -r334594 kernel failed

head -r334494 kernel worked
head -r334528 kernel failed

If 334494 ever fails, explore:

334474 (repeated to check: keeps working?)
334484 (the only archived powerpc64 build between 338474 and 338494)


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