Re: ACPI Thermal Shutdown on Boot

[Pavel Machek <pavel-AlSwsSmVLrQ@public.gmane.org>]

Hi!

> > > > > If I understand you correctly, 30 seconds is certainly
> > > > enough time to burn
> > > > > a CPU when the fan has failed, isn't it?
> > > >
> > > > Our old default poll interval was 30 seconds so this doesn't change
> > > > anything.  I know DeadRat takes more than 30 seconds from "shutdown -h
> > > > now" to power off.  All modern CPUs have a thermal shutdown builtin.
> > > > Think of _CRT as more of "system temp too high, shut down as
> > > > soon as you
> > > > can."
> > >
> > >   If I didn't miss something,  Chris Jensen was unable to adjust
> > > critical trip point due
> > > to current policy. Anyway, 57C isn't a real critical temperature. It
> > > doesn't make sense to
> > > enter emergent shutdown/power.So we need sane checking here.( A sane
> > > _CRT ?)
> > >   If FAN is broken, at least we can use throttling to guarantee it will
> > > not be over heated.
> > > So, throttling should be included into policy about handling critical
> > > trip point.
> >
> > At critical trip point, we have to shut down, according
> > to specs. No choice here.
> >
> > If their ACPI BIOS is b0rken, blacklist them.
> 
> My point was that shutdown to poweroff takes about 10 seconds on FreeBSD
> but much longer on common Linux distributions.  So even with a little
> delay, the system gets shut down at the same time.  This is better than
> blacklisting the system (a Compaq laptop) and not having any _CRT
> protection.  But Linux can do it however you want.

Well, hardware should protect itself at the end.

Can you see if this:

fixes stuff for you? You should see 'ACPI changed its mind...' in the
logs. (I wonder how to do this properly. Hardcoding 10Celsius is
broken...)

								Pavel

--- clean/drivers/acpi/thermal.c	2004-02-05 01:54:00.000000000 +0100
+++ linux/drivers/acpi/thermal.c	2004-02-05 02:24:15.000000000 +0100
@@ -223,8 +223,11 @@
 	tz->last_temperature = tz->temperature;
 
 	status = acpi_evaluate_integer(tz->handle, "_TMP", NULL, &tz->temperature);
-	if (ACPI_FAILURE(status))
+	if (ACPI_FAILURE(status)) {
+		if (tz->temperature != tz->last_temperature)
+			printk(KERN_ERR "temperature damaged while processing\n");
 		return -ENODEV;
+	}
 
 	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Temperature is %lu dK\n", tz->temperature));
 
@@ -457,7 +460,17 @@
 		return_VALUE(-EINVAL);
 
 	if (tz->temperature >= tz->trips.critical.temperature) {
+		long old_temperature = tz->temperature;
 		ACPI_DEBUG_PRINT((ACPI_DB_WARN, "Critical trip point\n"));
+
+		result = acpi_thermal_get_temperature(tz);
+		if (!result) {
+			if (tz->temperature < (tz->trips.critical.temperature - 100)) {
+				printk(KERN_ALERT "ACPI changed its mind about temperature, was %ld C, now %ld C", 
+				       KELVIN_TO_CELSIUS(old_temperature), KELVIN_TO_CELSIUS(tz->temperature));
+				return_VALUE(0);
+			}
+		}
 		tz->trips.critical.flags.enabled = 1;
 	}
 	else if (tz->trips.critical.flags.enabled)



-- 
When do you have a heart between your knees?
[Johanka's followup: and *two* hearts?]


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