[lm-sensors] Disabling fan control under Linux

[lm-sensors] Disabling fan control under Linux

[ICMP Request]

  Hello! I'm planning to install lm_sensors in my Linux platform using 
Gentoo, but I've got a little worried when I've read the following about 
lm_sensors on Gentoo Wiki:

"Warning: Be careful when activating sensors, like i2c, in the kernel. 
On some systems this might stop the fans from working and can disable 
the ACPI system-overheat shutdown as well. This will cause your computer 
to freeze at best, or may even cause serious hardware damage.

     * See the lm_sensors website for a problematic hardware list.
     * Using lm_sensors on IBM ThinkPads is especially not advised"

Well, I believe my hardware is in the supported list, but to avoid any 
problems, I would like to disable fan control under 
Linux/acpi/lm_sensors and any application using sensors, so they cannot 
turn my fan off. Fan would be purely controlled by hardware.

Can it be done by simply disabling the "fan" as built-in or module under 
ACPI?

Under Linux 2.6 Kernel:

Power management and ACPI options -> ACPI (Advanced Configuration and 
Power Interface) Support -> Fan =n

Or do I have to do something more complex?

Thanks in advance!

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Re: [lm-sensors] Disabling fan control under Linux

[ICMP Request]

  On 8/25/2010 2:43 AM, ICMP Request wrote:
>  Hello! I'm planning to install lm_sensors in my Linux platform using 
> Gentoo, but I've got a little worried when I've read the following 
> about lm_sensors on Gentoo Wiki:
>
> "Warning: Be careful when activating sensors, like i2c, in the kernel. 
> On some systems this might stop the fans from working and can disable 
> the ACPI system-overheat shutdown as well. This will cause your 
> computer to freeze at best, or may even cause serious hardware damage.
>
>     * See the lm_sensors website for a problematic hardware list.
>     * Using lm_sensors on IBM ThinkPads is especially not advised"
>
> Well, I believe my hardware is in the supported list, but to avoid any 
> problems, I would like to disable fan control under 
> Linux/acpi/lm_sensors and any application using sensors, so they 
> cannot turn my fan off. Fan would be purely controlled by hardware.
>
> Can it be done by simply disabling the "fan" as built-in or module 
> under ACPI?
>
> Under Linux 2.6 Kernel:
>
> Power management and ACPI options -> ACPI (Advanced Configuration and 
> Power Interface) Support -> Fan =n
>
> Or do I have to do something more complex?
>
> Thanks in advance!

Oh sorry, I've forgot to mention that I wish to disable turning my fan 
off but I still want to enable full acpi/lm_sensors to check my cpu 
temp/status, battery state, cpu freq scaling, etc. So is this possible 
to by doing what I mentioned above disable this single option but enable 
all the rest?

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Re: [lm-sensors] Disabling fan control under Linux

[Jean Delvare]

On Wed, 25 Aug 2010 02:53:20 -0300, ICMP Request wrote:
>   On 8/25/2010 2:43 AM, ICMP Request wrote:
> >  Hello! I'm planning to install lm_sensors in my Linux platform using 
> > Gentoo, but I've got a little worried when I've read the following 
> > about lm_sensors on Gentoo Wiki:
> >
> > "Warning: Be careful when activating sensors, like i2c, in the kernel. 
> > On some systems this might stop the fans from working and can disable 
> > the ACPI system-overheat shutdown as well. This will cause your 
> > computer to freeze at best, or may even cause serious hardware damage.

This point was addressed in kernel 2.6.32. If ACPI requested the I/O
ports of your hardware monitoring device (or SMBus controller, for
I2C/SMBus hardware monitoring devices), then native Linux drivers won't
touch it.

> >     * See the lm_sensors website for a problematic hardware list.

I am not aware of any such list on our website.

> >     * Using lm_sensors on IBM ThinkPads is especially not advised"

This last item is way outdated and should be removed. I'm running
lm-sensors on my own ThinkPad laptop and it works just fine.

> >
> > Well, I believe my hardware is in the supported list, but to avoid any 
> > problems, I would like to disable fan control under 
> > Linux/acpi/lm_sensors and any application using sensors, so they 
> > cannot turn my fan off. Fan would be purely controlled by hardware.
> >
> > Can it be done by simply disabling the "fan" as built-in or module 
> > under ACPI?
> >
> > Under Linux 2.6 Kernel:
> >
> > Power management and ACPI options -> ACPI (Advanced Configuration and 
> > Power Interface) Support -> Fan =n
> >
> > Or do I have to do something more complex?

I'm not sure what exactly loading the acpi "fan" driver does, but
probably not much. I think it is simply responsible for stopping the
fan when you suspend the machine.

> 
> Oh sorry, I've forgot to mention that I wish to disable turning my fan 
> off but I still want to enable full acpi/lm_sensors to check my cpu 
> temp/status, battery state, cpu freq scaling, etc. So is this possible 
> to by doing what I mentioned above disable this single option but enable 
> all the rest?

I don't think it makes much sense to disable the ACPI fan driver. If
anything is actually changing the fan's speed, it's not the ACPI fan
driver. If you don't want software-based fan speed control, then just
don't run pwmconfig, and you'll be safe.

Anyway, I can't add much as long as you don't tell us what your
hardware is, and how you believe the fan speed control (if there is
any) is achieved. Some machines have setting for this in the BIOS, some
don't. Some machines have ACPI-based control, some have monitoring
chips which can be programmed for automatic fan speed control.

-- 
Jean Delvare
http://khali.linux-fr.org/wishlist.html

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Re: [lm-sensors] Disabling fan control under Linux

[ICMP Request]

On 8/28/2010 5:20 AM, Jean Delvare wrote:
> On Wed, 25 Aug 2010 02:53:20 -0300, ICMP Request wrote:
>>    On 8/25/2010 2:43 AM, ICMP Request wrote:
>>>   Hello! I'm planning to install lm_sensors in my Linux platform using
>>> Gentoo, but I've got a little worried when I've read the following
>>> about lm_sensors on Gentoo Wiki:
>>>
>>> "Warning: Be careful when activating sensors, like i2c, in the kernel.
>>> On some systems this might stop the fans from working and can disable
>>> the ACPI system-overheat shutdown as well. This will cause your
>>> computer to freeze at best, or may even cause serious hardware damage.
> This point was addressed in kernel 2.6.32. If ACPI requested the I/O
> ports of your hardware monitoring device (or SMBus controller, for
> I2C/SMBus hardware monitoring devices), then native Linux drivers won't
> touch it.
>
>>>      * See the lm_sensors website for a problematic hardware list.
> I am not aware of any such list on our website.
>
>>>      * Using lm_sensors on IBM ThinkPads is especially not advised"
> This last item is way outdated and should be removed. I'm running
> lm-sensors on my own ThinkPad laptop and it works just fine.
>
>>> Well, I believe my hardware is in the supported list, but to avoid any
>>> problems, I would like to disable fan control under
>>> Linux/acpi/lm_sensors and any application using sensors, so they
>>> cannot turn my fan off. Fan would be purely controlled by hardware.
>>>
>>> Can it be done by simply disabling the "fan" as built-in or module
>>> under ACPI?
>>>
>>> Under Linux 2.6 Kernel:
>>>
>>> Power management and ACPI options ->  ACPI (Advanced Configuration and
>>> Power Interface) Support ->  Fan =n
>>>
>>> Or do I have to do something more complex?
> I'm not sure what exactly loading the acpi "fan" driver does, but
> probably not much. I think it is simply responsible for stopping the
> fan when you suspend the machine.
>
>> Oh sorry, I've forgot to mention that I wish to disable turning my fan
>> off but I still want to enable full acpi/lm_sensors to check my cpu
>> temp/status, battery state, cpu freq scaling, etc. So is this possible
>> to by doing what I mentioned above disable this single option but enable
>> all the rest?
> I don't think it makes much sense to disable the ACPI fan driver. If
> anything is actually changing the fan's speed, it's not the ACPI fan
> driver. If you don't want software-based fan speed control, then just
> don't run pwmconfig, and you'll be safe.
>
> Anyway, I can't add much as long as you don't tell us what your
> hardware is, and how you believe the fan speed control (if there is
> any) is achieved. Some machines have setting for this in the BIOS, some
> don't. Some machines have ACPI-based control, some have monitoring
> chips which can be programmed for automatic fan speed control.

Hello Jean! Thanks so much for answering! So, as far as I understood 
about your mail:

- On kernels 2.6.32 and higher, ACPI System Overheat Shutdown will no 
longer be disabled by any sensors-related driver, making it impossible 
to lm_sensors damage any hardware through overheat.
- There is NOT a list of problematic hardware at lm_sensors website (I 
also figured there was none).
- Recent lm_sensors versions on recent Kernels will not have any problem 
with an IBM Thinkpad.
- ACPI fan driver does not control the fan speed, neither is responsible 
for turning them off unless on shutdown. It is also not a dependency 
required by lm_sensors to work with the fans on a machine or turning 
them off, they are both unrelated.

Are these affirmations above all true? Or did I misunderstood something?

I was not really thinking about my machine in special, it was more a 
general question if one day I need to install lm_sensors in many 
machines with different configurations. For my machine, I've compiled 
2.6.34 Linux Kernel and loaded all hardware monitoring drivers as 
modules, as well as i2c, etc. and the only driver lm_sensors detected 
was "coretemp", which is the temperature monitoring driver for intel 
core2. There is also no option to enable/disable software fan control on 
BIOS.

So it seems that my machine is safe, by the simple lack of drivers to 
control the fan or even see anything but the processor temperature.

I'm about to buy a motherboard with Intel P55 Express Chipset and core 
i5 processor, and I hope it doesn't present problems on kernel 2.6.34+ 
and lm_sensors 3.1.2+ related to hardware damaging.

But, as you said, I should not worry about any machine because on recent 
kernel and lm_sensors versions, they are all immune to damage through 
overheat? Even the IBM Thinkpads?

If you and/or more can confirm that I understood it correct, I will be 
very grateful and also suggest Gentoo Linux Community to upgrade their 
wiki, linking this thread for reference.

Thanks again!

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Re: [lm-sensors] Disabling fan control under Linux

[Jean Delvare]

On Sat, 28 Aug 2010 17:49:45 -0300, ICMP Request wrote:
> On 8/28/2010 5:20 AM, Jean Delvare wrote:
> > Anyway, I can't add much as long as you don't tell us what your
> > hardware is, and how you believe the fan speed control (if there is
> > any) is achieved. Some machines have setting for this in the BIOS, some
> > don't. Some machines have ACPI-based control, some have monitoring
> > chips which can be programmed for automatic fan speed control.
> 
> Hello Jean! Thanks so much for answering! So, as far as I understood 
> about your mail:
> 
> - On kernels 2.6.32 and higher, ACPI System Overheat Shutdown will no 
> longer be disabled by any sensors-related driver, making it impossible 
> to lm_sensors damage any hardware through overheat.

On any system where ACPI properly requests the I/O ports it uses, yes.
A system where ACPI would use ports it didn't request, lm-sensors could
still cause trouble, but that's the BIOS's fault, not ours.

> - There is NOT a list of problematic hardware at lm_sensors website (I 
> also figured there was none).
> - Recent lm_sensors versions on recent Kernels will not have any problem 
> with an IBM Thinkpad.
> - ACPI fan driver does not control the fan speed, neither is responsible 
> for turning them off unless on shutdown. It is also not a dependency 
> required by lm_sensors to work with the fans on a machine or turning 
> them off, they are both unrelated.

Yes, yes and yes.

> Are these affirmations above all true? Or did I misunderstood something?
> 
> I was not really thinking about my machine in special, it was more a 
> general question if one day I need to install lm_sensors in many 
> machines with different configurations. For my machine, I've compiled 
> 2.6.34 Linux Kernel and loaded all hardware monitoring drivers as 
> modules, as well as i2c, etc. and the only driver lm_sensors detected 
> was "coretemp", which is the temperature monitoring driver for intel 
> core2. There is also no option to enable/disable software fan control on 
> BIOS.
> 
> So it seems that my machine is safe, by the simple lack of drivers to 
> control the fan or even see anything but the processor temperature.

Correct.

> I'm about to buy a motherboard with Intel P55 Express Chipset and core 
> i5 processor, and I hope it doesn't present problems on kernel 2.6.34+ 
> and lm_sensors 3.1.2+ related to hardware damaging.

This question can't be answered without the motherboard vendor and
model name. And even then, you'd need to find someone with the same
board to gather the information needed to answer the question.

> But, as you said, I should not worry about any machine because on recent 
> kernel and lm_sensors versions, they are all immune to damage through 
> overheat? Even the IBM Thinkpads?

Yes. The main problem we have these days is that lm-sensors won't work
on some systems, exactly because ACPI is stealing I/O ports from us.
But hardware damage would be very very rare, probably not more frequent
than with any other hardware-related project.

> If you and/or more can confirm that I understood it correct, I will be 
> very grateful and also suggest Gentoo Linux Community to upgrade their 
> wiki, linking this thread for reference.

Thanks :)

-- 
Jean Delvare

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