[MinnowBoard] Problem reading CPU temp in linux (yocto build)

[Zhang, Austin]

That value 26800 is one gotten from BIOS ACPI method which OS will call when you do something like 'cat /sys/...'.

So that means: either the BIOS ACPI routine ran into trouble so always return one fixed value, or the ACPI method was not implemented correctly at all.

Thanks. 

-----Original Message-----
From: elinux-MinnowBoard [mailto:elinux-minnowboard-bounces at lists.elinux.org] On Behalf Of Gerard Bucas
Sent: Thursday, April 30, 2015 6:04 AM
To: nb
Cc: MinnowBoard Development and Community Discussion
Subject: Re: [MinnowBoard] Problem reading CPU temp in linux (yocto build)

Thanks - that's what I though (& also see!)

I wonder how we can fix that!?

Curious... 

Gerard



> On Apr 29, 2015, at 5:46 PM, nb <nb at dagami.org> wrote:
> 
> Hi,
> 
> I always have same value (26.8°C), whatever the cpu does.
> 
> Regards
> 
> nb
> 
> 
>> Le 29 avr. 2015 à 22:38, Gerard Bucas <gerard.b at tekmagic.net> a écrit :
>> 
>> Hi nb
>> 
>> Thanks but I see that your  temp ALSO returns 26.8C (same as mine!!). That is the 'problem', no matter what the chip temp is (could be too hot to even touch under heavy load) - the temp returned is ALWAYS 26.8C!!!
>> 
>> Have a look and let me know if that is also what you observe (seems like it from what you wrote as it is too much of a co-incidence that you get EXACTLY the same value as I do - hot or cold!!)
>> 
>> Thanks
>> 
>> Gerard
>> 
>> 
>>> On Apr 29, 2015, at 4:24 PM, nb <nb at dagami.org> wrote:
>>> 
>>> Hi Gerard,
>>> 
>>> On my Debian:
>>> 
>>> sensors
>>> acpitz-virtual-0
>>> Adapter: Virtual device
>>> temp1:        +26.8°C  (crit = +90.0°C)
>>> 
>>> coretemp-isa-0000
>>> Adapter: ISA adapter
>>> Core 0:       +50.0°C  (high = +110.0°C, crit = +110.0°C)
>>> Core 2:       +51.0°C  (high = +110.0°C, crit = +110.0°C)
>>> 
>>> So it’s the same (sensors is in lm-sensors package)
>>> 
>>> Regards
>>> 
>>> nb
>>> 
>>> 
>>>> Le 29 avr. 2015 à 22:04, Gerard Bucas <gerard.b at tekmagic.net> a écrit :
>>>> 
>>>> Hi Everyone,
>>>> 
>>>> We use linux (custom built with yocto project) on minnowBoard MAX. Works great!
>>>> 
>>>> However, I have a problem reading the CPU core temperature of the E3825. 
>>>> When I use this command line:
>>>> 
>>>> cat /sys/class/thermal/thermal_zone0/temp
>>>> 
>>>> It ALWAYS returns the value: 26800 (= 26.8C)
>>>> 
>>>> Linux kernel version: 3.19.2-yocto-standard
>>>> 
>>>> Build Configuration:
>>>> BB_VERSION        = "1.27.0"
>>>> BUILD_SYS         = "x86_64-linux"
>>>> NATIVELSBSTRING   = "Ubuntu-14.04"
>>>> TARGET_SYS        = "x86_64-poky-linux"
>>>> MACHINE           = "intel-corei7-64" (recommended by Intel for Atom E38XX SoC & minnowBoard MAX)
>>>> DISTRO            = "poky"
>>>> DISTRO_VERSION    = "1.8+snapshot-20150429"
>>>> 
>>>> It looks like this value is hard-coded in the kernel! In researching this on the internet it seems that many people have this problem with a variety of Intel based CPU's/SoC's on a variety of different linux distributions. 
>>>> 
>>>> Has anyone else solved this problem or do you know of another linux command line that would give me the CPU (chip) temperature?
>>>> 
>>>> I have tried to add the "lm-sensors" package but have had problems adding it to my yocto build as I can't seem to find the right "package group" that includes lm-sensors.
>>>> Any ideas/help would be MUCH appreciated!
>>>> 
>>>> Thanks
>>>> Gerard
>>>> 
>>>> _______________________________________________
>>>> elinux-MinnowBoard mailing list
>>>> elinux-MinnowBoard at lists.elinux.org
>>>> http://lists.elinux.org/mailman/listinfo/elinux-minnowboard
> 
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