echo 75000 > /sys/class/thermal/thermal_zone0/trip_point_1_temp - Permission denied!!

[Colin Ian King]

On 09/06/14 17:57, John Hupp wrote:
> On 6/9/2014 10:20 AM, Seth Forshee wrote:
>> On Thu, Jun 05, 2014 at 10:39:46AM -0400, John Hupp wrote:
>>> Trying to edit an acpi thermal trip point, I show from
>>> /sys/class/thermal/thermal_zone0:
>>>
>>> $ echo 75000 > trip_point_1_temp
>>> bash: trip_point_1_temp: Permission denied
>> This command isn't going to work unless you're in a root shell.
>>
>>> I get the same result using sudo.
>> Is it really the same, or does it say "Operation not permitted" instead?
>> If so, then it probably means that the driver behind that trip point
>> does not support changing the trip point temperature (which isn't
>> necessarily a bug, it might really be impossible to change it).
> 
> Yes, I verify "Permission  denied":
> $ sudo sh -c "echo 75000 > trip_point_1_temp"
> sh: 1: cannot create trip_point_1_temp: Permission denied
> 
> Since posting, I found this 2007 article that says the kernel no longer
> (as of 2.6.22) supports changing the trip points:
> http://lwn.net/Articles/244595/
> 
> Many people reportedly complained about that kernel change, so I wonder,
> is the current kernel design still such that the trip points cannot be
> changed?
> 
> Since there are currently no active fan cooling trip points set for this
> Lenovo 3000, only the passive one at 87 C and the critical one at 102 C,
> if I want some active cooling, is my only recourse to modify the DSDT? 
> That would seem like a needlessly deep dive, but I'd like to know if
> it's my only option.

You may like to give thermald a try, it may prove useful in preventing
overheating.

See https://wiki.ubuntu.com/Kernel/PowerManagement/ThermalIssues

> 
>>> I also tried with the same result:
>>>
>>> $ echo 75000 | sudo tee trip_point_1_temp
>>> and
>>> $ sudo sh -c "echo 75000 > trip_point_1_temp"
>>>
>>> I also tried "echo -n" instead of just "echo" with the same result.
>>>
>>> I also tried echo "75000" instead of just echo 75000.
>>>
>>> I also tried the above commands from
>>> /sys/devices/virtual/thermal/thermal_zone0 (where the links from
>>> /sys/class/thermal point), all with the same result.
>>>
>>> These thermal attributes are supposed to be editable by the user,
>>> and this is confirmed by
>>> https://www.kernel.org/doc/Documentation/thermal/x86_pkg_temperature_thermal
>>>
>>>
>>> I have read that there was one or more bugs in the past that behaved
>>> this way.  Do we have a new bug?
>>>
>>>
>>> -- 
>>> kernel-team mailing list
>>> kernel-team at lists.ubuntu.com
>>> https://lists.ubuntu.com/mailman/listinfo/kernel-team
> 
>