Phenom II 975 BE shows 0 celsius

[Jung-uk Kim]

On Monday 01 August 2011 03:03 pm, Andriy Gapon wrote:
> [cc list trimmed]
>
> on 01/08/2011 19:23 Jung-uk Kim said the following:
> > I gave up the DiodeOffset recently because a lot of BIOSes do not
> > set any meaningful values.  Instead, I added a tunable for that. 
> > Please see the attached patch, which is also available from here:
> >
> > http://people.freebsd.org/~jkim/amdtemp.diff
>
> I haven't tried your patch yet, but already have a few comments :-)
>
> - at least on head pci_cfgregread() is public via
> x86/include/pci_cfgreg.h

That's cool.  Thanks.

> - I am not sure if you really need it; shouldn't pci_read_config()
> just work since amdtemp attaches under pci bus?

amdtemp(4) attaches under PCI bus but its sibling on function 2 isn't 
easy to address, i.e., hostbN.

> - about erratum 319 - I feel like objecting to amdtemp_force_enable
> approach; given the wide spread of AM2+ and AM3 in consumer boards,
> and the very important fact that I have AM2+ and I have never
> observed (with my own eyes) incorrect reading from amdtemp, and the
> less important fact that the output of amdtemp is not used for
> anything critical (for anything at all, in fact) in the base
> system, and that that would be a kind of POLA violation (which is
> PITA) - I propose to just print some warning message on the
> affected systems; at most, export that warning as a sysctl node

I have mixed feeling about this because I own a system with such 
CPU/motherboard combo, too.  I also believe it works well but errata 
is errata.  If vendor says we shouldn't use it, then we shouldn't.  
In fact, I am just following Linux as an example here but I have no 
problem with turning this into a warning message, either.  AMD says 
it shouldn't be interpreted as physical temperature but we are doing 
it anyway. ;-)

Jung-uk Kim

> Finally, I promise to test this patch soon-ish.
> Thank you for digging into this!