Re: [PATCH] AMD Thermal Interrupt Support

Andi Kleen
2008-01-04T22:24:41Z

> As to the question of Athlon RevG, it turns out that it has the same
> thermal erratum as RevF. Therefore the fact that this code only works
> with Barcelona and up is not a defficiency.

Thanks.

>
> There are 2 pending issues, to which I have received insufficient feedback:
>
> 1. Andi would like to eliminate the trampoline in mce_thermal.c, but
> no one has responded to my proposed disgusting hack on entry_64.S in
> order to do so.

There are two ways to do it:

either duplicate the entry point in entry_64.S and set different
vectors or let the asm glue jump through a call vector (use
apicinterrupt ...,*thermal_vector(%rip) ) Later is probably better.

>
> 2. Ingo pointed out that a given config file did not build. But when

The patch that was in git-x86 didn't build on 32bit. Perhaps it was a
32bit config file? Run it under "linux32" or equivalent on your distro.

> + */
> + if (therm_throt_process(1))
> + mce_log_therm_throt_event(cpu, 1);
> + /*
> + * We'll still get subsequent interrupts even if we don't clear the
> + * status bit in THERM_CTL_F3X64. Take advantage of this fact to avoid
> + * touching PCI space. (If this assumption fails at some point, we'll
> + * need to schedule_work() in order to enter a process context, so that
> + * PCI locks can be asserted for proper access. This requirement, in

PCI locks are spinlocks so they don't need process context. In PREEMPT-RT
kernels they can sleep, but there the handler will be likely already
a thread. Touching config space from interrupt context is legal, although
not very popular because it tends to be slow (but a few drivers do it)

> + /*
> + * If any of the northbridges has PCI ID 0x1103, then its thermal
> + * hardware suffers from an erratum which prevents this code from
> + * working, so abort.

Please add

* This implies it only works on Family 10h aka AMD Quad Core.

Otherwise I can just see the support questions of people asking why this
doesn't work for them.

Anyways I'm unsure about the blacklist here -- white list would
probably have been better. k8_northbridges[] will certainly include
Griffin northtbridges and who knows if TT will work there or not.
[sorry for mentioning that not earlier]

-Andi