Re: cpu temperature readings

[Robert Elz <kre%munnari.OZ.AU@localhost>]

Sorry, no, I can't test, the system looks to have died, and certainly
needs repairs, it looks as if the cooler might be dead (not sure about
the cpu at the minute, it won't even boot to the stage where the BIOS
enables the display)

However, much of what your patch does (according to your description,
at the minute my method of e-mail access doesn't rise to looking at
attachments) is what I actually put in the kernel I was running.
I didn't change the lower limit on the range, for me that was clearly
not a problem, and I made the upper limit 130 instead of 120 (though
as it turned out, either would do).   My system sets Tjmax to 115.
That seems to be a constant, every read of the register, on all cores,
produces 115 (I added a diagnostic to tell me if it ever changed).

I can't comment on what should be done in the case of the value being
outside the expected range - I don't know enough about PC hardware to
know whether or not there are systems which might return garbage in
that register - if there are, then settling on a default to use sounds
like the right way, but if nothing is known to do that, thenjust believing
what the CPU says (as we do with any other register) - with or without
a disgnostic to the console would probably be better.

This time (Weds evening) when the system shut down, I had just finished
a build, and run (some) ATF tests to check some changes I was making to
sh quoting in some of the test scripts (there is some horribly bogus
nonsense around...  though as long as the data being used doesn't change
there would be no adverse effects in the tests I looked at, so the
change I was working on should be made, but won't actually change
any results - the ATF test runs I did verified that).

During the build the core temps were fluctuating about Tjmax (115)
which I didn't consider all that abnormal (the previous build I did,
before the Tjmax adjustment, did much the same thing).  The difference
this time was that things never cooled down after the build finished.

Further, before I could get to commit the changes, the "critical temp"
bit started being set (all cores) and powerd shut down the system.
I had a diagnostic to print the register that has the bit in it,
and also (if it managed to read properly) the temp that had been
read (in micro-kelvins, as the value has been converted by this time).
I took a photo of the data on the screen while (some of) that data
was visible, if it is likely to be useful to anyone.
(That's on my phone, so no problem accessing it).

Note that until my system gets repaired (and I won't even start looking
for a local reputable repair place until Monday at least) I am going
to be fairly sluggish accessing e-mail (I won't be looking very
frequently, and might easily miss messages when I do look, as I
get to see incoming messages without any spam filtering yet when I
access it this way).

kre