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

[John Hupp]

On 6/9/2014 1:22 PM, Colin Ian King wrote:
> 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

This looks like the best thing since sliced bread -- the very sort of 
solution needed in this case.  I'm looking into it further. Thanks!

>
>>>> 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
>>
>