Kernel panic on PowerMac G5 while scanning for SMU sensors

Kernel panic on PowerMac G5 while scanning for SMU sensors

[Phileas Fogg]

I wanted to read the temperature sensors of my PowerMac G5 11,2.
For that i installed the lm-sensors package, run 'sensors-detect' 
command and my Linux 3.8.2 kernel paniced in

_smu_i2c_low_completion_

with this message

'Unable to handle kernel paging request for data at address 0x00000008.'

Regards

Re: Kernel panic on PowerMac G5 while scanning for SMU sensors

[Phileas Fogg]

On 03/17/2013 01:07 PM, Phileas Fogg wrote:
>
> I wanted to read the temperature sensors of my PowerMac G5 11,2.
> For that i installed the lm-sensors package, run 'sensors-detect'
> command and my Linux 3.8.2 kernel paniced in
>
> _smu_i2c_low_completion_
>
> with this message
>
> 'Unable to handle kernel paging request for data at address 0x00000008.'
>
> Regards
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev@lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/linuxppc-dev

A further analysis showed that it crashes in _smu_i2c_complete_command_
which is called from _smu_i2c_low_completion_.

This line caused the panic:

list_del(&cmd->link);

regards

Re: Kernel panic on PowerMac G5 while scanning for SMU sensors

[Benjamin Herrenschmidt]

On Sun, 2013-03-17 at 13:42 +0100, Phileas Fogg wrote:

> A further analysis showed that it crashes in _smu_i2c_complete_command_
> which is called from _smu_i2c_low_completion_.
> 
> This line caused the panic:
> 
> list_del(&cmd->link);

Ok, we must have a bug :-) I'm on holiday for a while, I can look when
I'm back.

However, I would generally advise against messing around with the
sensors directly from userspace which is what I believe lm-sensors does.
It has no real understanding of what those sensors are about, where they
are located etc... and might also conflict with the use of those sensors
by the kernel windfarm drivers.

If you want to look at the values, windfarm does expose them to
userspace in sysfs, you might want to take a peek.

Cheers,
Ben.