cannot access acpi interface

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cannot access acpi interface

fa-ml
Hello list,

        I recently bought a Thinkpad X60s [1] and I am in the process of
installing software/customising it to my own needs.

I wanted to make some leds blink upon receiving mail, so I started by
probing the acpi interface

    $ root@x60s:/proc/acpi/ibm# cat led
    status:         supported
    commands:       <led> on, <led> off, <led> blink (<led> is 0-15)

Reading this I tried:

    $ root@x60s:/proc/acpi/ibm# echo "15 on" > led
    bash: echo: write error: Operation not permitted

Has anyone of you encountered the same problem? Is there a workaround?
I suspect the solution lies in booting the kernel with a particular
parameter (alas, I did not find which one).
Thanks in advance
-F

[1] http://shop.gluglug.org.uk/product/ibm-lenovo-thinkpad-x60-w-coreboot-wo-extras/
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Re: cannot access acpi interface

Paul Bolle
On Tue, 2014-02-11 at 08:27 +0100, fa-ml wrote:
> Reading this I tried:
>
>     $ root@x60s:/proc/acpi/ibm# echo "15 on" > led
>     bash: echo: write error: Operation not permitted
>
> Has anyone of you encountered the same problem? Is there a workaround?

From Documentation/laptops/thinkpad-acpi.txt:
    LED control
    -----------

    procfs: /proc/acpi/ibm/led
    sysfs attributes: as per LED class, see below for names

    [...]

    Because misuse of the LEDs could induce an unaware user to perform
    dangerous actions (like undocking or ejecting a bay device while the
    buses are still active), or mask an important alarm (such as a nearly
    empty battery, or a broken battery), access to most LEDs is
    restricted.

    Unrestricted access to all LEDs requires that thinkpad-acpi be
    compiled with the CONFIG_THINKPAD_ACPI_UNSAFE_LEDS option enabled.
    Distributions must never enable this option.  Individual users that
    are aware of the consequences are welcome to enabling it.

Perhaps you are trying to access one of the unsafe leds.


Paul Bolle

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Re: cannot access acpi interface

fa-ml
On Tue, Feb 11, 2014 at 09:39:21AM +0100, Paul Bolle wrote:
> From Documentation/laptops/thinkpad-acpi.txt:
> [...]
>
> Perhaps you are trying to access one of the unsafe leds.
>
>
> Paul Bolle

Clear and to the point, thanks!
I guess I will find a different method for mail notifications.
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