Re: Linux 2.6.25 (coretemp reads high temperatures)

Re: Linux 2.6.25 (coretemp reads high temperatures)

[Len Brown]

On Friday 18 April 2008, Matthew wrote:
> Hi everyone, hi Linus,
> 
> congratulations on this new great kernel-release :)
> 
> I've another "regression" to report for 2.6.25:
> 
> it's concerning much higher temperatures being read out by the
> "coretemp" kernel-module in comparison to 2.6.24* series
> 
> e.g. where temperatures were around 40-47°C they are now constantly
> jumping around 55-70°C (even in idle !)
> 
> several other users/testers have reported this issue too (both on
> zen-sources [heavy patched] & latest gentoo-sources) [slightly
> patched]:
> 
> http://forums.gentoo.org/viewtopic-t-684812-highlight-.html
> 
> if I understood git right it (also) happens in conjunction with an 3
> weeks old acpi-snapshot
> (http://repo.or.cz/w/linux-2.6/zen-sources.git?a=heads) integrated in
> zen-sources
> 
> I can "reproduce" this on an Intel Core 2 Duo 6600 (Conroe) with a P5W
> DH Deluxe mainboard (by Asus) since at least 2.6.25-rc8 (or possibly
> also rc7)
> 
> the temperatures on mobile core (2) duo intel processors [e.g. an
> T7500] seem to be read out correctly - I can't tell it exactly but
> this seems to be an entirely "cosmetical" issue
> (hopefully it's not the opposite and the values are now read out
> correctly since such high temps would be very worrying ;) )
> 
> Keep up the great work & please don't forget your growing amount of
> linux-desktop users :)
> 
> Regards
> 
> Mat

Hello Mat,
I'm not familiar with "coretemp", can you point me to the exact version
of the application you are running so I can see how it is getting at
the underlying information?

Also, do you see any change with and without kernel built with CONFIG_THERMAL=y?

thanks,
-Len

Re: Linux 2.6.25 (coretemp reads high temperatures)

[Thomas Bächler]

[-- Attachment #1: Type: text/plain, Size: 1238 bytes --]

Len Brown schrieb:
> Hello Mat,
> I'm not familiar with "coretemp", can you point me to the exact version
> of the application you are running so I can see how it is getting at
> the underlying information?

I think there is some confusion here: "coretemp" is a kernel module, and 
all applications reading it will probably use the lm_sensors libraries. 
(I don't think the hwmon module are related to ACPI)

$ modinfo coretemp
filename:       /lib/modules/2.6.25-ARCH/kernel/drivers/hwmon/coretemp.ko
license:        GPL
description:    Intel Core temperature monitor
author:         Rudolf Marek <r.marek@assembler.cz>
depends:
vermagic:       2.6.25-ARCH SMP preempt mod_unload

That said, I have two Core 2 CPUs (one mobile, one desktop) and the 
values coretemp reports have not changed compared to earlier kernel 
versions (around 60°C when idle on the mobile, much less on the desktop).

 > Also, do you see any change with and without kernel built with 
CONFIG_THERMAL=y?

The values I see from ACPI thermal are also the same as before (this is 
funny: they are always about 15°C cooler than the coretemp values).

So I don't see a regression here, maybe the reporter should try a 
vanilla kernel.


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Re: Linux 2.6.25 (coretemp reads high temperatures)

[Maxim Levitsky]

On Saturday, 19 April 2008 04:51:48 Len Brown wrote:
> On Friday 18 April 2008, Matthew wrote:
> > Hi everyone, hi Linus,
> > 
> > congratulations on this new great kernel-release :)
> > 
> > I've another "regression" to report for 2.6.25:
> > 
> > it's concerning much higher temperatures being read out by the
> > "coretemp" kernel-module in comparison to 2.6.24* series
> > 
> > e.g. where temperatures were around 40-47°C they are now constantly
> > jumping around 55-70°C (even in idle !)

I just updated from 2.6.24 to 2.6.25
(I usually follow whole development cycle, but I was very busy, so I skipped 2.6.25 cycle)

I confirm this.
I *know* that temperatures reported now are wrong.

The reason is that bios did report same temperatures as coretemp in 2.6.24,
moreover some time ago I have run a cpu tool (don't remember its name) on windows
which similar to coretemp reads from each core directly, sensor data , 
and I noticed that temperature that bios reports is exactly the average 
temperature of both cores
(I had to run this on windows - intel haven't released 
drivers for their QST for temperature monitoring from bios - very sad)

And the driver did say in kernel log that TJMAX is 85C

Lets at least make a kernel option to override tjmax?

Best regards,
	Maxim Levitsky
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Re: Linux 2.6.25 (coretemp reads high temperatures)

[Kasper Sandberg]

On Wed, 2008-04-23 at 11:43 +0300, Maxim Levitsky wrote:
> On Saturday, 19 April 2008 04:51:48 Len Brown wrote:
> > On Friday 18 April 2008, Matthew wrote:
> > > Hi everyone, hi Linus,
> > > 
> > > congratulations on this new great kernel-release :)
> > > 
> > > I've another "regression" to report for 2.6.25:
> > > 
> > > it's concerning much higher temperatures being read out by the
> > > "coretemp" kernel-module in comparison to 2.6.24* series
> > > 
> > > e.g. where temperatures were around 40-47°C they are now constantly
> > > jumping around 55-70°C (even in idle !)
> 
> I just updated from 2.6.24 to 2.6.25
> (I usually follow whole development cycle, but I was very busy, so I skipped 2.6.25 cycle)
> 
> I confirm this.
> I *know* that temperatures reported now are wrong.

I too can confirm that it reports incorrect temperatures.

I have a Q9450, and this is my "sensors" output:
it8718-isa-0290
Adapter: ISA adapter
<snip>
temp1:       +44°C  (low  =  +127°C, high =  +127°C)   sensor =
thermistor
temp2:       +22°C  (low  =  +127°C, high =   +60°C)   sensor = diode
temp3:        -2°C  (low  =  +127°C, high =  +127°C)   sensor =
thermistor
vid:      +0.000 V

coretemp-isa-0000
Adapter: ISA adapter
Core 0:      +44°C  (high =  +100°C)

coretemp-isa-0001
Adapter: ISA adapter
Core 1:      +44°C  (high =  +100°C)

coretemp-isa-0002
Adapter: ISA adapter
Core 2:      +43°C  (high =  +100°C)

coretemp-isa-0003
Adapter: ISA adapter
Core 3:      +41°C  (high =  +100°C)


temp2 is the cpu temperature(matches bios), temp1 is the northbridge(i
think, bios says "system temp").

i have watercooling, and well :P when i touch the "tube", its normal
room temperature, and believe me, i would notice if it was 45.. this is
with my cpu at idle - at full load on all 4 cores, temp2 says 35, and
~60 on coretemp, and THIS i would surely be able to notice over room
temp :)

any progress on this bug?

> 
> The reason is that bios did report same temperatures as coretemp in 2.6.24,
> moreover some time ago I have run a cpu tool (don't remember its name) on windows
> which similar to coretemp reads from each core directly, sensor data , 
> and I noticed that temperature that bios reports is exactly the average 
> temperature of both cores
> (I had to run this on windows - intel haven't released 
> drivers for their QST for temperature monitoring from bios - very sad)
> 
> And the driver did say in kernel log that TJMAX is 85C
> 
> Lets at least make a kernel option to override tjmax?
> 
> Best regards,
> 	Maxim Levitsky
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
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Re: Linux 2.6.25 (coretemp reads high temperatures)

[Thomas Renninger]

On Mon, 2008-04-28 at 20:19 +0200, Kasper Sandberg wrote:
> On Wed, 2008-04-23 at 11:43 +0300, Maxim Levitsky wrote:
> > On Saturday, 19 April 2008 04:51:48 Len Brown wrote:
> > > On Friday 18 April 2008, Matthew wrote:
> > > > Hi everyone, hi Linus,
> > > > 
> > > > congratulations on this new great kernel-release :)
> > > > 
> > > > I've another "regression" to report for 2.6.25:
> > > > 
> > > > it's concerning much higher temperatures being read out by the
> > > > "coretemp" kernel-module in comparison to 2.6.24* series
> > > > 
> > > > e.g. where temperatures were around 40-47°C they are now constantly
> > > > jumping around 55-70°C (even in idle !)
> > 
> > I just updated from 2.6.24 to 2.6.25
> > (I usually follow whole development cycle, but I was very busy, so I skipped 2.6.25 cycle)
> > 
> > I confirm this.
> > I *know* that temperatures reported now are wrong.
> 
> I too can confirm that it reports incorrect temperatures.
> 
> I have a Q9450, and this is my "sensors" output:
> it8718-isa-0290
> Adapter: ISA adapter
> <snip>
> temp1:       +44°C  (low  =  +127°C, high =  +127°C)   sensor =
> thermistor
> temp2:       +22°C  (low  =  +127°C, high =   +60°C)   sensor = diode
> temp3:        -2°C  (low  =  +127°C, high =  +127°C)   sensor =
> thermistor
> vid:      +0.000 V
> 
> coretemp-isa-0000
> Adapter: ISA adapter
> Core 0:      +44°C  (high =  +100°C)
> 
> coretemp-isa-0001
> Adapter: ISA adapter
> Core 1:      +44°C  (high =  +100°C)
> 
> coretemp-isa-0002
> Adapter: ISA adapter
> Core 2:      +43°C  (high =  +100°C)
> 
> coretemp-isa-0003
> Adapter: ISA adapter
> Core 3:      +41°C  (high =  +100°C)
> 
> 
> temp2 is the cpu temperature(matches bios), temp1 is the northbridge(i
> think, bios says "system temp").
> 
> i have watercooling, and well :P when i touch the "tube", its normal
> room temperature, and believe me, i would notice if it was 45.. this is
> with my cpu at idle - at full load on all 4 cores, temp2 says 35, and
> ~60 on coretemp, and THIS i would surely be able to notice over room
> temp :)
> 
> any progress on this bug?
> 
> > 
> > The reason is that bios did report same temperatures as coretemp in 2.6.24,
> > moreover some time ago I have run a cpu tool (don't remember its name) on windows
> > which similar to coretemp reads from each core directly, sensor data , 
> > and I noticed that temperature that bios reports is exactly the average 
> > temperature of both cores
> > (I had to run this on windows - intel haven't released 
> > drivers for their QST for temperature monitoring from bios - very sad)
> > 
> > And the driver did say in kernel log that TJMAX is 85C
> > 
> > Lets at least make a kernel option to override tjmax?
> > 

Could it be that due to latest thermal changes ACPI is reading
temperatures more often, or started to read sensors that interfere with
libsensors?

There was a patch-set that detect such interference from myself and Jean
which was not accepted by Linus.
This is what I got from Jean recently, he should be able to point you to
the latest patches if you want to give them a try:
----------------------------------------------
On Mon, 28 Apr 2008 22:13:13 -0700, Andrew Morton wrote:
> In light of Linus's dummyspit last time around I guess I'll drop
> this patch.

That's OK, I'll include it in my i2c tree instead. While Linus doesn't
like it, he didn't actually provide replacement code, only a vague idea
which Thomas and myself know by experience, won't work well anyway. As
the checks done by this driver are valuable, having it in -mm and
linux-next is still good.

-- 
Jean Delvare
----------------------------------------------


If you get a conflict you should see something like this when loading
the hwmon/sensor driver:
i2c /dev entries driver
f71805f: Found F71805F/FG chip at 0x290, revision 19
ACPI: I/O resource f71805f [0x290-0x297] conflicts with ACPI region IP__ [0x295-0x296]
ACPI: Device needs an ACPI driver

   Thomas

Re: Linux 2.6.25 (coretemp reads high temperatures)

[Jean Delvare]

Hi all,

Adding Rudolf Marek to the thread, as he wrote the coretemp driver and
is maintaining it. He was really the first person to contact about your
problem...

On Tue, 29 Apr 2008 15:07:03 +0200, Thomas Renninger wrote:
> On Mon, 2008-04-28 at 20:19 +0200, Kasper Sandberg wrote:
> > On Wed, 2008-04-23 at 11:43 +0300, Maxim Levitsky wrote:
> > > On Saturday, 19 April 2008 04:51:48 Len Brown wrote:
> > > > On Friday 18 April 2008, Matthew wrote:
> > > > > Hi everyone, hi Linus,
> > > > > 
> > > > > congratulations on this new great kernel-release :)
> > > > > 
> > > > > I've another "regression" to report for 2.6.25:
> > > > > 
> > > > > it's concerning much higher temperatures being read out by the
> > > > > "coretemp" kernel-module in comparison to 2.6.24* series
> > > > > 
> > > > > e.g. where temperatures were around 40-47°C they are now constantly
> > > > > jumping around 55-70°C (even in idle !)
> > > 
> > > I just updated from 2.6.24 to 2.6.25
> > > (I usually follow whole development cycle, but I was very busy, so I skipped 2.6.25 cycle)
> > > 
> > > I confirm this.
> > > I *know* that temperatures reported now are wrong.

And how do you know? The newly reported temperatures could be correct
and the previous ones were incorrect (that's actually the case.) The
thing is, the temperature is stored as a relative value in the CPU.
Relative to what, depends on the CPU model, can be 85°C or 100°C. Up to
kernel 2.6.24 we had a set of rules to find out, in 2.6.25 we have a
presumably better heuristic. So some people have seen their CPU
temperature climb by 15°C and others drop by 15°C, that's expected.

> > 
> > I too can confirm that it reports incorrect temperatures.
> > 
> > I have a Q9450, and this is my "sensors" output:
> > it8718-isa-0290
> > Adapter: ISA adapter
> > <snip>
> > temp1:       +44°C  (low  =  +127°C, high =  +127°C)   sensor = thermistor
> > temp2:       +22°C  (low  =  +127°C, high =   +60°C)   sensor = diode
> > temp3:        -2°C  (low  =  +127°C, high =  +127°C)   sensor = thermistor
> > vid:      +0.000 V
> > 
> > coretemp-isa-0000
> > Adapter: ISA adapter
> > Core 0:      +44°C  (high =  +100°C)
> > 
> > coretemp-isa-0001
> > Adapter: ISA adapter
> > Core 1:      +44°C  (high =  +100°C)
> > 
> > coretemp-isa-0002
> > Adapter: ISA adapter
> > Core 2:      +43°C  (high =  +100°C)
> > 
> > coretemp-isa-0003
> > Adapter: ISA adapter
> > Core 3:      +41°C  (high =  +100°C)
> > 
> > 
> > temp2 is the cpu temperature(matches bios), temp1 is the northbridge(i
> > think, bios says "system temp").
> > 
> > i have watercooling, and well :P when i touch the "tube", its normal
> > room temperature, and believe me, i would notice if it was 45.. this is
> > with my cpu at idle - at full load on all 4 cores, temp2 says 35, and
> > ~60 on coretemp, and THIS i would surely be able to notice over room
> > temp :)

The coretemp driver reports the CPU _core_ temperature. That's not
something you can touch, believe me (unless you are an electron.)

Also note that the CPU temperature reported by the IT8718F may or may
not match the reality. To make sure, you'd need to know the type of
thermal diode expected by the IT8718F, the type of thermal diode in
your CPU, compute the correction factor if there is one. And you'd need
to know where the thermal diode is exactly. It is most certainly built
into the CPU, but some motherboard makers are doing weird things.

22°C seems very low to me, even for water-cooling. Note that
non-linearity of thermal diodes makes measurements inaccurate as they
get away from the expected operating point. I guess that thermal diodes
used in CPUs are calibrated for best results around the expected
temperature when using air-cooling, rather than water-cooling.

> > 
> > any progress on this bug?

I still need to be convinced that there is a bug here.

> > 
> > > 
> > > The reason is that bios did report same temperatures as coretemp in 2.6.24,
> > > moreover some time ago I have run a cpu tool (don't remember its name) on windows

In my experience, the BIOS is more likely to get the information from
the on-board hardware monitoring chip than from the CPU MSRs as the
coretemp driver does.

> > > which similar to coretemp reads from each core directly, sensor data , 
> > > and I noticed that temperature that bios reports is exactly the average 

If that windows tool was not written by Intel, then chances are that
the author had as much difficulties as we did to get the correct TJmax
values for the different CPU models, so it's hardly meaningful. And
even a tool written by Intel themselves, I wouldn't necessarily trust
it, given how hard it was to get the information from them.

> > > temperature of both cores
> > > (I had to run this on windows - intel haven't released 
> > > drivers for their QST for temperature monitoring from bios - very sad)
> > > 
> > > And the driver did say in kernel log that TJMAX is 85C

Which driver, which kernel? As I wrote above, the coretemp heuristic
changed in kernel 2.6.25, so the fact that a previous kernel was
reporting a different tjmax value is irrelevant. Unless you have
additional documentation from Intel, I would tend to believe that the
coretemp driver in 2.6.25 is correct. But feel free to report the exact
CPU model you have (with CPUID info) to Rudolf, if he gets enough
reports about a specific CPU model which most people believe gets the
wrong tjmax, he can fix the driver.

> > > 
> > > Lets at least make a kernel option to override tjmax?

That's a possibility for sure, but what we would really need is to
adjust the coretemp driver heuristics to always get it right - if
that's not already the case, that is. I'll let Rudolf decide anyway.

Note that all in all, the absolute temperature doesn't really matter
anyway. What matters is how far you are from TJmax.

> Could it be that due to latest thermal changes ACPI is reading
> temperatures more often, or started to read sensors that interfere with
> libsensors?

No, there's a much more simple explanation for this change users are
reporting, see above. Plus, I fail to see how ACPI could interfere with
the coretemp driver as all, as it gets its values from MSRs and not I/O
ports.

-- 
Jean Delvare

Re: Linux 2.6.25 (coretemp reads high temperatures)

[Rudolf Marek]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Hi all,

I already answered this thread while ago. I can just confirm what Jean told.

>>>> I confirm this.
>>>> I *know* that temperatures reported now are wrong.
> 
> And how do you know? The newly reported temperatures could be correct
> and the previous ones were incorrect (that's actually the case.) The
> thing is, the temperature is stored as a relative value in the CPU.
> Relative to what, depends on the CPU model, can be 85°C or 100°C. Up to
> kernel 2.6.24 we had a set of rules to find out, in 2.6.25 we have a
> presumably better heuristic. So some people have seen their CPU
> temperature climb by 15°C and others drop by 15°C, that's expected.

Yes exactly. I decided to move to 0-100C scale, and move the limit too.
Of course some users with too low jumped to better scale some like you seems to
complain now.

>>> i have watercooling, and well :P when i touch the "tube", its normal
>>> room temperature, and believe me, i would notice if it was 45.. this is
>>> with my cpu at idle - at full load on all 4 cores, temp2 says 35, and
>>> ~60 on coretemp, and THIS i would surely be able to notice over room
>>> temp :)
> 
> The coretemp driver reports the CPU _core_ temperature. That's not
> something you can touch, believe me (unless you are an electron.)
> 
> Also note that the CPU temperature reported by the IT8718F may or may
> not match the reality. To make sure, you'd need to know the type of
> thermal diode expected by the IT8718F, the type of thermal diode in
> your CPU, compute the correction factor if there is one. And you'd need
> to know where the thermal diode is exactly. It is most certainly built
> into the CPU, but some motherboard makers are doing weird things.
> 
> 22°C seems very low to me, even for water-cooling. Note that
> non-linearity of thermal diodes makes measurements inaccurate as they
> get away from the expected operating point. I guess that thermal diodes
> used in CPUs are calibrated for best results around the expected
> temperature when using air-cooling, rather than water-cooling.
> 
>>> any progress on this bug?
> 
> I still need to be convinced that there is a bug here.

It is not a bug, a max limit changed too, it is just matter how to scale it. The
temperature is non-physical so comparing it to physical temperature does not
make any sense. I'm sorry I did not invent this relative temp stuff - Complain
@intel. They have some calibration of TjMAX for mobiles, but this bit does not
work for desktops/servers. I tried really hard to get at LEAST some
documentation so the driver looks like it looks. And not
guessed/guessed/guessed/how it looked earlier.

> 
>>>> The reason is that bios did report same temperatures as coretemp in 2.6.24,
>>>> moreover some time ago I have run a cpu tool (don't remember its name) on windows

It was most likely coretemp - I'm in contact with the guy. We share infos.

>>>> temperature of both cores
>>>> (I had to run this on windows - intel haven't released 
>>>> drivers for their QST for temperature monitoring from bios - very sad)
>>>>
>>>> And the driver did say in kernel log that TJMAX is 85C
> 
> Which driver, which kernel? As I wrote above, the coretemp heuristic
> changed in kernel 2.6.25, so the fact that a previous kernel was
> reporting a different tjmax value is irrelevant. Unless you have
> additional documentation from Intel, I would tend to believe that the
> coretemp driver in 2.6.25 is correct. But feel free to report the exact
> CPU model you have (with CPUID info) to Rudolf, if he gets enough
> reports about a specific CPU model which most people believe gets the
> wrong tjmax, he can fix the driver.

Well again, I tried hard at Intel and I really could not get any info on some
calibration bit. The temperature is non-physical on arbitrary scale. I changed
that so for some people it jumped to 100C, for some it remained.

>>>> Lets at least make a kernel option to override tjmax?
> 
> That's a possibility for sure, but what we would really need is to
> adjust the coretemp driver heuristics to always get it right - if
> that's not already the case, that is. I'll let Rudolf decide anyway.

Well again, Intel swears there is no way how to get the TjMAX for
desktops/servers. It sucks but this is not my fault.

Thanks,
Rudolf






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Re: Linux 2.6.25 (coretemp reads high temperatures)

[Matthew]

>
>  Hi all,
>
>  I already answered this thread while ago. I can just confirm what Jean told.
>
>
>  >>>> I confirm this.
>  >>>> I *know* that temperatures reported now are wrong.
>  >
>  > And how do you know? The newly reported temperatures could be correct
>  > and the previous ones were incorrect (that's actually the case.) The
>  > thing is, the temperature is stored as a relative value in the CPU.
>  > Relative to what, depends on the CPU model, can be 85°C or 100°C. Up to
>  > kernel 2.6.24 we had a set of rules to find out, in 2.6.25 we have a
>  > presumably better heuristic. So some people have seen their CPU
>  > temperature climb by 15°C and others drop by 15°C, that's expected.
>
>  Yes exactly. I decided to move to 0-100C scale, and move the limit too.
>  Of course some users with too low jumped to better scale some like you seems to
>  complain now.
>
>
>  >>> i have watercooling, and well :P when i touch the "tube", its normal
>  >>> room temperature, and believe me, i would notice if it was 45.. this is
>  >>> with my cpu at idle - at full load on all 4 cores, temp2 says 35, and
>  >>> ~60 on coretemp, and THIS i would surely be able to notice over room
>  >>> temp :)
>  >
>  > The coretemp driver reports the CPU _core_ temperature. That's not
>  > something you can touch, believe me (unless you are an electron.)
>  >
>  > Also note that the CPU temperature reported by the IT8718F may or may
>  > not match the reality. To make sure, you'd need to know the type of
>  > thermal diode expected by the IT8718F, the type of thermal diode in
>  > your CPU, compute the correction factor if there is one. And you'd need
>  > to know where the thermal diode is exactly. It is most certainly built
>  > into the CPU, but some motherboard makers are doing weird things.
>  >
>  > 22°C seems very low to me, even for water-cooling. Note that
>  > non-linearity of thermal diodes makes measurements inaccurate as they
>  > get away from the expected operating point. I guess that thermal diodes
>  > used in CPUs are calibrated for best results around the expected
>  > temperature when using air-cooling, rather than water-cooling.
>  >
>  >>> any progress on this bug?
>  >
>  > I still need to be convinced that there is a bug here.
>
>  It is not a bug, a max limit changed too, it is just matter how to scale it. The
>  temperature is non-physical so comparing it to physical temperature does not
>  make any sense. I'm sorry I did not invent this relative temp stuff - Complain
>  @intel. They have some calibration of TjMAX for mobiles, but this bit does not
>  work for desktops/servers. I tried really hard to get at LEAST some
>  documentation so the driver looks like it looks. And not
>  guessed/guessed/guessed/how it looked earlier.
>
>
>  >
>  >>>> The reason is that bios did report same temperatures as coretemp in 2.6.24,
>  >>>> moreover some time ago I have run a cpu tool (don't remember its name) on windows
>
>  It was most likely coretemp - I'm in contact with the guy. We share infos.
>
>
>  >>>> temperature of both cores
>  >>>> (I had to run this on windows - intel haven't released
>  >>>> drivers for their QST for temperature monitoring from bios - very sad)
>  >>>>
>  >>>> And the driver did say in kernel log that TJMAX is 85C
>  >
>  > Which driver, which kernel? As I wrote above, the coretemp heuristic
>  > changed in kernel 2.6.25, so the fact that a previous kernel was
>  > reporting a different tjmax value is irrelevant. Unless you have
>  > additional documentation from Intel, I would tend to believe that the
>  > coretemp driver in 2.6.25 is correct. But feel free to report the exact
>  > CPU model you have (with CPUID info) to Rudolf, if he gets enough
>  > reports about a specific CPU model which most people believe gets the
>  > wrong tjmax, he can fix the driver.
>
>  Well again, I tried hard at Intel and I really could not get any info on some
>  calibration bit. The temperature is non-physical on arbitrary scale. I changed
>  that so for some people it jumped to 100C, for some it remained.
>
>
>  >>>> Lets at least make a kernel option to override tjmax?
>  >
>  > That's a possibility for sure, but what we would really need is to
>  > adjust the coretemp driver heuristics to always get it right - if
>  > that's not already the case, that is. I'll let Rudolf decide anyway.
>
>  Well again, Intel swears there is no way how to get the TjMAX for
>  desktops/servers. It sucks but this is not my fault.
>
>  Thanks,
>  Rudolf
>


Hi Rudolf, hi @ all,

so we were just too concerned all the time & even though the
temperatures seem too high there's nothing to worry ?

I'd be more tranquilized if I had the old temperatures ;)
but like lm_sensors's output states - it's not bad until  I / we're
getting temperatures from 85°C (?) [in this particular case], ...


@lkml, Linus:

sorry for all the noise ;)



Len,

here's the output of sensors (lm_sensors):

with acpi thermal-support compiled in:

w83627ehf-isa-0290
Adapter: ISA adapter
VCore:       +1.12 V  (min =  +0.00 V, max =  +1.74 V)
in1:        +12.36 V  (min = +13.46 V, max = +13.46 V)   ALARM
AVCC:        +3.34 V  (min =  +4.08 V, max =  +2.03 V)   ALARM
3VCC:        +3.34 V  (min =  +3.92 V, max =  +3.95 V)   ALARM
in4:         +1.70 V  (min =  +1.53 V, max =  +2.04 V)
in5:         +1.59 V  (min =  +2.04 V, max =  +1.02 V)   ALARM
in6:         +5.12 V  (min =  +6.53 V, max =  +6.32 V)   ALARM
VSB:         +3.26 V  (min =  +3.06 V, max =  +4.08 V)
VBAT:        +3.20 V  (min =  +4.02 V, max =  +4.02 V)   ALARM
in9:         +1.61 V  (min =  +2.04 V, max =  +2.04 V)   ALARM
Case Fan:      0 RPM  (min =    0 RPM, div = 128)
CPU Fan:     969 RPM  (min =    0 RPM, div = 8)
Aux Fan:    3970 RPM  (min =    0 RPM, div = 2)
fan4:          0 RPM  (min =   83 RPM, div = 128)  ALARM
fan5:       1308 RPM  (min =    0 RPM, div = 8)
Sys Temp:    +39.0°C  (high = +123.0°C, hyst = -65.0°C)  sensor = thermistor
CPU Temp:    +29.0°C  (high = +80.0°C, hyst = +75.0°C)  sensor = diode
AUX Temp:   +121.5°C  (high = +80.0°C, hyst = +75.0°C)  ALARM  sensor
= thermistor
cpu0_vid:   +1.350 V

coretemp-isa-0000
Adapter: ISA adapter
Core 0:      +60.0°C  (high = +84.0°C, crit = +100.0°C)

coretemp-isa-0001
Adapter: ISA adapter
Core 1:      +57.0°C  (high = +84.0°C, crit = +100.0°C)

-----------------------------------------------------------------------------------------------------------------------------------------------------------------------

and without:

w83627ehf-isa-0290
Adapter: ISA adapter
VCore:       +1.30 V  (min =  +0.00 V, max =  +1.74 V)
in1:        +12.30 V  (min = +13.46 V, max = +13.46 V)   ALARM
AVCC:        +3.36 V  (min =  +4.08 V, max =  +2.03 V)   ALARM
3VCC:        +3.34 V  (min =  +3.92 V, max =  +3.95 V)   ALARM
in4:         +1.70 V  (min =  +1.53 V, max =  +2.04 V)
in5:         +1.59 V  (min =  +2.04 V, max =  +1.02 V)   ALARM
in6:         +5.12 V  (min =  +6.53 V, max =  +6.32 V)   ALARM
VSB:         +3.26 V  (min =  +3.06 V, max =  +4.08 V)
VBAT:        +3.20 V  (min =  +4.02 V, max =  +4.02 V)   ALARM
in9:         +1.61 V  (min =  +2.04 V, max =  +2.04 V)   ALARM
Case Fan:      0 RPM  (min =    0 RPM, div = 128)
CPU Fan:     986 RPM  (min =    0 RPM, div = 8)
Aux Fan:    3970 RPM  (min =    0 RPM, div = 2)
fan4:          0 RPM  (min =   83 RPM, div = 128)  ALARM
fan5:       1308 RPM  (min =    0 RPM, div = 8)
Sys Temp:    +39.0°C  (high = +123.0°C, hyst = -65.0°C)  sensor = thermistor
CPU Temp:    +29.0°C  (high = +80.0°C, hyst = +75.0°C)  sensor = diode
AUX Temp:   +117.0°C  (high = +80.0°C, hyst = +75.0°C)  ALARM  sensor
= thermistor
cpu0_vid:   +1.375 V

coretemp-isa-0000
Adapter: ISA adapter
Core 0:      +60.0°C  (high = +84.0°C, crit = +100.0°C)

coretemp-isa-0001
Adapter: ISA adapter
Core 1:      +58.0°C  (high = +84.0°C, crit = +100.0°C)

-----------------------------------------------------------------------------------------------------------------------------------------------------------------------

it's the completely same temperatures - it had no effect on the
"correctness" of the output


thanks to everyone

Regards

Mat
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Re: Linux 2.6.25 (coretemp reads high temperatures)

[Jean Delvare]

On Wed, 30 Apr 2008 00:58:50 +0200, Matthew wrote:
> so we were just too concerned all the time & even though the
> temperatures seem too high there's nothing to worry ?

Yes.

> I'd be more tranquilized if I had the old temperatures ;)

Note that you can easily get them back by tweaking your sensors.conf
file:

chip "coretemp-*"

    compute temp1 @-15, @+15

But I wouldn't do it, as it doesn't make much sense.

> but like lm_sensors's output states - it's not bad until  I / we're
> getting temperatures from 85°C (?) [in this particular case], ...

If I remember correctly, at 84°C your CPU will start to throttle, at
100°C it will shut down. You still have 24°C before the former happens,
so it should be OK.

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Re: Linux 2.6.25 (coretemp reads high temperatures)

[Henrique de Moraes Holschuh]

On Wed, 30 Apr 2008, Jean Delvare wrote:
> On Wed, 30 Apr 2008 00:58:50 +0200, Matthew wrote:
> > so we were just too concerned all the time & even though the
> > temperatures seem too high there's nothing to worry ?
> 
> Yes.

So the big deal here is that there is no "°C" anywhere in this
measurement, it is in an arbitrary hardware scale?

> > but like lm_sensors's output states - it's not bad until  I / we're
> > getting temperatures from 85°C (?) [in this particular case], ...
> 
> If I remember correctly, at 84°C your CPU will start to throttle, at
> 100°C it will shut down. You still have 24°C before the former happens,
> so it should be OK.

Better drop the °C from there.  It starts throttling at 84 ITUs and
shuts down at 100 ITUs (Intel Thermal Units :p).

-- 
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  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh
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Re: Linux 2.6.25 (coretemp reads high temperatures)

[Rudolf Marek]

>>> but like lm_sensors's output states - it's not bad until  I / we're
>>> getting temperatures from 85°C (?) [in this particular case], ...
>> If I remember correctly, at 84°C your CPU will start to throttle, at
>> 100°C it will shut down. You still have 24°C before the former happens,
>> so it should be OK.

The high limit is when the all fans should go max. Throttle is at crit.

Rudolf
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Re: Linux 2.6.25 (coretemp reads high temperatures)

[Jean Delvare]

On Wed, 30 Apr 2008 16:50:59 +0200, Rudolf Marek wrote:
> >>> but like lm_sensors's output states - it's not bad until  I / we're
> >>> getting temperatures from 85°C (?) [in this particular case], ...
> >> If I remember correctly, at 84°C your CPU will start to throttle, at
> >> 100°C it will shut down. You still have 24°C before the former happens,
> >> so it should be OK.
> 
> The high limit is when the all fans should go max. Throttle is at crit.

Ah, sorry then, I remembered incorrectly.

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Re: Linux 2.6.25 (coretemp reads high temperatures)

[Pavel Machek]

Hi!

> > On Wed, 30 Apr 2008 00:58:50 +0200, Matthew wrote:
> > > so we were just too concerned all the time & even though the
> > > temperatures seem too high there's nothing to worry ?
> > 
> > Yes.
> 
> So the big deal here is that there is no "°C" anywhere in this
> measurement, it is in an arbitrary hardware scale?
> 
> > > but like lm_sensors's output states - it's not bad until  I / we're
> > > getting temperatures from 85°C (?) [in this particular case], ...
> > 
> > If I remember correctly, at 84°C your CPU will start to throttle, at
> > 100°C it will shut down. You still have 24°C before the former happens,
> > so it should be OK.
> 
> Better drop the °C from there.  It starts throttling at 84 ITUs and
> shuts down at 100 ITUs (Intel Thermal Units :p).

degrees Intel? :-)

If t1-t2 == 1ITU, is that 1degC?

> -- 
>   "One disk to rule them all, One disk to find them. One disk to bring
>   them all and in the darkness grind them. In the Land of Redmond
>   where the shadows lie." -- The Silicon Valley Tarot
>   Henrique Holschuh
> --
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Re: Linux 2.6.25 (coretemp reads high temperatures)

[Kasper Sandberg]

On Wed, 2008-04-30 at 00:14 +0200, Rudolf Marek wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> Hi all,
> 
> I already answered this thread while ago. I can just confirm what Jean told.
> 
> >>>> I confirm this.
> >>>> I *know* that temperatures reported now are wrong.
> > 
> > And how do you know? The newly reported temperatures could be correct
> > and the previous ones were incorrect (that's actually the case.) The
> > thing is, the temperature is stored as a relative value in the CPU.
> > Relative to what, depends on the CPU model, can be 85°C or 100°C. Up to
> > kernel 2.6.24 we had a set of rules to find out, in 2.6.25 we have a
> > presumably better heuristic. So some people have seen their CPU
> > temperature climb by 15°C and others drop by 15°C, that's expected.
> 
> Yes exactly. I decided to move to 0-100C scale, and move the limit too.
> Of course some users with too low jumped to better scale some like you seems to
> complain now.
> 
> >>> i have watercooling, and well :P when i touch the "tube", its normal
> >>> room temperature, and believe me, i would notice if it was 45.. this is
> >>> with my cpu at idle - at full load on all 4 cores, temp2 says 35, and
> >>> ~60 on coretemp, and THIS i would surely be able to notice over room
> >>> temp :)
> > 
> > The coretemp driver reports the CPU _core_ temperature. That's not
> > something you can touch, believe me (unless you are an electron.)
> > 
> > Also note that the CPU temperature reported by the IT8718F may or may
> > not match the reality. To make sure, you'd need to know the type of
> > thermal diode expected by the IT8718F, the type of thermal diode in
> > your CPU, compute the correction factor if there is one. And you'd need
> > to know where the thermal diode is exactly. It is most certainly built
> > into the CPU, but some motherboard makers are doing weird things.
> > 
> > 22°C seems very low to me, even for water-cooling. Note that
> > non-linearity of thermal diodes makes measurements inaccurate as they
> > get away from the expected operating point. I guess that thermal diodes
> > used in CPUs are calibrated for best results around the expected
> > temperature when using air-cooling, rather than water-cooling.
> > 
> >>> any progress on this bug?
> > 
> > I still need to be convinced that there is a bug here.
> 
> It is not a bug, a max limit changed too, it is just matter how to scale it. The
> temperature is non-physical so comparing it to physical temperature does not
> make any sense. I'm sorry I did not invent this relative temp stuff - Complain
> @intel. They have some calibration of TjMAX for mobiles, but this bit does not
> work for desktops/servers. I tried really hard to get at LEAST some
> documentation so the driver looks like it looks. And not
> guessed/guessed/guessed/how it looked earlier.
> 
> > 
> >>>> The reason is that bios did report same temperatures as coretemp in 2.6.24,
> >>>> moreover some time ago I have run a cpu tool (don't remember its name) on windows
> 
> It was most likely coretemp - I'm in contact with the guy. We share infos.
> 
> >>>> temperature of both cores
> >>>> (I had to run this on windows - intel haven't released 
> >>>> drivers for their QST for temperature monitoring from bios - very sad)
> >>>>
> >>>> And the driver did say in kernel log that TJMAX is 85C
> > 
> > Which driver, which kernel? As I wrote above, the coretemp heuristic
> > changed in kernel 2.6.25, so the fact that a previous kernel was
> > reporting a different tjmax value is irrelevant. Unless you have
> > additional documentation from Intel, I would tend to believe that the
> > coretemp driver in 2.6.25 is correct. But feel free to report the exact
> > CPU model you have (with CPUID info) to Rudolf, if he gets enough
> > reports about a specific CPU model which most people believe gets the
> > wrong tjmax, he can fix the driver.
> 
> Well again, I tried hard at Intel and I really could not get any info on some
> calibration bit. The temperature is non-physical on arbitrary scale. I changed
> that so for some people it jumped to 100C, for some it remained.

So, im confused.. The reason for this is that the internal sensor is
operating on some sort of weird scale, and thus when you interpolate it
into "your" scale, it doesent quite come out in the actual degrees
celcius the cpu temperature really is?

so if i understand this correctly, the coretemp output does NOT
represent the actual deg celcius temperature my cpu is?

> 
> >>>> Lets at least make a kernel option to override tjmax?
> > 
> > That's a possibility for sure, but what we would really need is to
> > adjust the coretemp driver heuristics to always get it right - if
> > that's not already the case, that is. I'll let Rudolf decide anyway.
> 
> Well again, Intel swears there is no way how to get the TjMAX for
> desktops/servers. It sucks but this is not my fault.
> 
> Thanks,
> Rudolf
> 
> 
> 
> 
> 
> 
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG v1.4.6 (GNU/Linux)
> Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org
> 
> iD8DBQFIF5203J9wPJqZRNURAnFSAKC3GpafvkviWggGJPG2o71R4lel0wCgirnW
> Cr2RidnTZEdKTAj8yEviR0U=
> =lFMk
> -----END PGP SIGNATURE-----

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Re: Linux 2.6.25 (coretemp reads high temperatures)

[Jean Delvare]

On Wed, 30 Apr 2008 02:11:14 +0200, Kasper Sandberg wrote:
> On Wed, 2008-04-30 at 00:14 +0200, Rudolf Marek wrote:
> > Well again, I tried hard at Intel and I really could not get any info on some
> > calibration bit. The temperature is non-physical on arbitrary scale. I changed
> > that so for some people it jumped to 100C, for some it remained.
> 
> So, im confused.. The reason for this is that the internal sensor is
> operating on some sort of weird scale, and thus when you interpolate it
> into "your" scale, it doesent quite come out in the actual degrees
> celcius the cpu temperature really is?

It's really only an offset, rather than scaling. The temperature
reported by the Core and Core2 CPUs is a relative temperature. It tells
how far you are from the maximum temperature the CPU can survive. The
value is expressed in (relative) degrees C.

Rudolf did his best to find out the (absolute) temperature each CPU
model can survive (known as TJmax) so that the coretemp driver can
provide an absolute temperature to user-space, as all other hardware
monitoring drivers do. Our hope was to limit the confusion, but it
seems we failed ;) Maybe it would be better if the driver was reporting
the relative temperature value directly when we don't know the TJmax
value for sure - but then all user-space tools would need to learn how
to deal with this.

> so if i understand this correctly, the coretemp output does NOT
> represent the actual deg celcius temperature my cpu is?

It should, but there's no guarantee on desktop/server CPUs. It can be
offset by 15°C if the driver's heuristic to determine TJmax for your
CPU is incorrect. I guess the offset could even be different - after
all the documentation we got from Intel was incomplete so we don't
really know.

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Re: Linux 2.6.25 (coretemp reads high temperatures)

[Henrique de Moraes Holschuh]

On Wed, 30 Apr 2008, Jean Delvare wrote:
> On Wed, 30 Apr 2008 02:11:14 +0200, Kasper Sandberg wrote:
> > On Wed, 2008-04-30 at 00:14 +0200, Rudolf Marek wrote:
> > > Well again, I tried hard at Intel and I really could not get any info on some
> > > calibration bit. The temperature is non-physical on arbitrary scale. I changed
> > > that so for some people it jumped to 100C, for some it remained.
> > 
> > So, im confused.. The reason for this is that the internal sensor is
> > operating on some sort of weird scale, and thus when you interpolate it
> > into "your" scale, it doesent quite come out in the actual degrees
> > celcius the cpu temperature really is?
> 
> It's really only an offset, rather than scaling. The temperature
> reported by the Core and Core2 CPUs is a relative temperature. It tells
> how far you are from the maximum temperature the CPU can survive. The
> value is expressed in (relative) degrees C.

Ah, please ignore my email about ITUs (Intel thermal units), then.  The
above means 1ITU=1°C, but their zeros are at different places.

> Rudolf did his best to find out the (absolute) temperature each CPU
> model can survive (known as TJmax) so that the coretemp driver can
> provide an absolute temperature to user-space, as all other hardware
> monitoring drivers do. Our hope was to limit the confusion, but it
> seems we failed ;) Maybe it would be better if the driver was reporting
> the relative temperature value directly when we don't know the TJmax
> value for sure - but then all user-space tools would need to learn how
> to deal with this.

Actually, just libsensors would, and the local admin can adjust it at
will using the config file.

Nobody in userspace should be reading hwmon sysfs directly without the
use of libsensors.  If they are, it is their bug, and it is unsupported
AFAIK.

-- 
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  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh
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Re: Linux 2.6.25 (coretemp reads high temperatures)

[Jean Delvare]

On Wed, 30 Apr 2008 11:51:10 -0300, Henrique de Moraes Holschuh wrote:
> On Wed, 30 Apr 2008, Jean Delvare wrote:
> > On Wed, 30 Apr 2008 02:11:14 +0200, Kasper Sandberg wrote:
> > > So, im confused.. The reason for this is that the internal sensor is
> > > operating on some sort of weird scale, and thus when you interpolate it
> > > into "your" scale, it doesent quite come out in the actual degrees
> > > celcius the cpu temperature really is?
> > 
> > It's really only an offset, rather than scaling. The temperature
> > reported by the Core and Core2 CPUs is a relative temperature. It tells
> > how far you are from the maximum temperature the CPU can survive. The
> > value is expressed in (relative) degrees C.
> 
> Ah, please ignore my email about ITUs (Intel thermal units), then.  The
> above means 1ITU=1°C, but their zeros are at different places.
> 

Correct. 1ITU=1°C as a difference between temperatures but not as
absolute temperatures.

> > Rudolf did his best to find out the (absolute) temperature each CPU
> > model can survive (known as TJmax) so that the coretemp driver can
> > provide an absolute temperature to user-space, as all other hardware
> > monitoring drivers do. Our hope was to limit the confusion, but it
> > seems we failed ;) Maybe it would be better if the driver was reporting
> > the relative temperature value directly when we don't know the TJmax
> > value for sure - but then all user-space tools would need to learn how
> > to deal with this.
> 
> Actually, just libsensors would, and the local admin can adjust it at
> will using the config file.

Hmm, good point. I had not considered that we could hide this detail
inside libsensors. I'll need to think about it.

That being said, in practice that would probably not be too different
from just making temp1_crit writable in the coretemp driver.

> 
> Nobody in userspace should be reading hwmon sysfs directly without the
> use of libsensors.

Except for the features which are not supported by libsensors (e.g.
pwm).

> If they are, it is their bug, and it is unsupported AFAIK.

Unsupported by me, certainly, and stupid as well for sure, especially
given the amount of work that has gone into the new libsensors API to
avoid this.

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Re: Linux 2.6.25 (coretemp reads high temperatures)

[Pavel Machek]

Hi!

> > > So, im confused.. The reason for this is that the internal sensor is
> > > operating on some sort of weird scale, and thus when you interpolate it
> > > into "your" scale, it doesent quite come out in the actual degrees
> > > celcius the cpu temperature really is?
> > 
> > It's really only an offset, rather than scaling. The temperature
> > reported by the Core and Core2 CPUs is a relative temperature. It tells
> > how far you are from the maximum temperature the CPU can survive. The
> > value is expressed in (relative) degrees C.
> 
> Ah, please ignore my email about ITUs (Intel thermal units), then.  The
> above means 1ITU=1°C, but their zeros are at different places.
> 
> > Rudolf did his best to find out the (absolute) temperature each CPU
> > model can survive (known as TJmax) so that the coretemp driver can
> > provide an absolute temperature to user-space, as all other hardware
> > monitoring drivers do. Our hope was to limit the confusion, but it
> > seems we failed ;) Maybe it would be better if the driver was reporting
> > the relative temperature value directly when we don't know the TJmax
> > value for sure - but then all user-space tools would need to learn how
> > to deal with this.
> 
> Actually, just libsensors would, and the local admin can adjust it at
> will using the config file.
> 
> Nobody in userspace should be reading hwmon sysfs directly without the
> use of libsensors.  If they are, it is their bug, and it is unsupported
> AFAIK.

Hmm, that's an interesting ABI design. No, I do not think that's a
good idea.

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Re: Linux 2.6.25 (coretemp reads high temperatures)

[Henrique de Moraes Holschuh]

On Fri, 02 May 2008, Pavel Machek wrote:
> > Actually, just libsensors would, and the local admin can adjust it at
> > will using the config file.
> > 
> > Nobody in userspace should be reading hwmon sysfs directly without the
> > use of libsensors.  If they are, it is their bug, and it is unsupported
> > AFAIK.
> 
> Hmm, that's an interesting ABI design. No, I do not think that's a
> good idea.

That's how it is.  The kernel drivers are to attempt to do their best to
give proper readings.  But if they don't, the library can apply
arbritary user-configurable adjustments.

I'd rather different attribute names like "raw_temp#" were used when the
adjustment thorugh libsensors is *required*, though.

-- 
  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh

Re: Linux 2.6.25 (coretemp reads high temperatures)

[Pavel Machek]

On Sun 2008-05-04 14:42:29, Henrique de Moraes Holschuh wrote:
> On Fri, 02 May 2008, Pavel Machek wrote:
> > > Actually, just libsensors would, and the local admin can adjust it at
> > > will using the config file.
> > > 
> > > Nobody in userspace should be reading hwmon sysfs directly without the
> > > use of libsensors.  If they are, it is their bug, and it is unsupported
> > > AFAIK.
> > 
> > Hmm, that's an interesting ABI design. No, I do not think that's a
> > good idea.
> 
> That's how it is.  The kernel drivers are to attempt to do their best to
> give proper readings.  But if they don't, the library can apply
> arbritary user-configurable adjustments.
> 
> I'd rather different attribute names like "raw_temp#" were used when the
> adjustment thorugh libsensors is *required*, though.

Yes, that would be nice.
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: Linux 2.6.25 (coretemp reads high temperatures)

[Pavel Machek]

Hi!


> > I still need to be convinced that there is a bug here.
> 
> It is not a bug, a max limit changed too, it is just matter how to scale it. The
> temperature is non-physical so comparing it to physical temperature does not
> make any sense. I'm sorry I did not invent this relative temp stuff - Complain
> @intel. They have some calibration of TjMAX for mobiles, but this bit does not
> work for desktops/servers. I tried really hard to get at LEAST some
> documentation so the driver looks like it looks. And not
> guessed/guessed/guessed/how it looked earlier.

If absolute temperature is not known, could we move it to some
obviously invalid range, so that people would not treat it as absolute
temperature?

Like, set tjmax == 0K, and report relative temperatures below 0K? Or
move it to 100-200C range, which is obviously invalid?

Or maybe invent 'relative temperature' attribute?

> >>>> Lets at least make a kernel option to override tjmax?
> > 
> > That's a possibility for sure, but what we would really need is to
> > adjust the coretemp driver heuristics to always get it right - if
> > that's not already the case, that is. I'll let Rudolf decide anyway.
> 
> Well again, Intel swears there is no way how to get the TjMAX for
> desktops/servers. It sucks but this is not my fault.

Uff, does it differ between cpus with same stepping/etc?

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: Linux 2.6.25

[Matthew]

>Hello Mat,
>I'm not familiar with "coretemp", can you point me to the exact version
>of the application you are running so I can see how it is getting at
>the underlying information?

>Also, do you see any change with and without kernel built with
CONFIG_THERMAL=y?

>thanks,
>-Len

Hi Len,

sure, the apps I am using for reading out the processor's temp via
coretemp are / were:
lm_sensors: version 2.10.4, 2.10.6 and (currently) 3.0.1: all report
the same (higher) temperatures (compared to 2.6.24 series)

CONFIG_THERMAL currently is enabled in the kernel:
grep CONFIG_THERMAL /usr/src/linux/.config
CONFIG_THERMAL=y

I'll recompile the kernel now & let you know the effect in a few hours
(currently I'm working on the box)

"Dairinin" on forums.gentoo.org pointed out that the desktop-cpu
simply might not be identified correctly:
http://forums.gentoo.org/viewtopic-p-5065902.html#5065902

"Thats because new kernel (lm_sensors, etc?, etc?)incorrectly thinks
our cpu's Tj is 100C, whereas for all core 2 duo's it is 85C (100C is
for C0 stepping and above, AFAIK). Substract 15 and you'll get real
temps."

I don't know if that's the case but it sounds plausible to me

thanks everyone for your answer & help so far

Regards

Mat