Re: [lm-sensors] [RFC] Support of chassis intrusion detection

[Hans de Goede <j.w.r.degoede@hhs.nl>]

Jean Delvare wrote:
> On Thu, 19 Feb 2009 10:37:33 +0100, Hans de Goede wrote:
>> Jean Delvare wrote:
>>> Hi all,
>>>
>>> A number of users have asked us to support the chassis intrusion
>>> detection feature which some hardware monitoring chip have. I've
>>> created a ticket for this:
>>> http://www.lm-sensors.org/ticket/2370
>>> Here is a proposal.
>>>
>>> sysfs interface
>>> =======>>>
>>> chassis_intrusion
>>> 		Chassis intrusion detection
>>> 		0: OK
>>> 		1: intrusion detected
>>> 		RW
>>> 		Writing 0 clears the detection flag.
>>> 		Writing other values is unsupported.
>>>
> 
> Having thought about it some more, I suspect this won't be sufficient.
> This feature is like an alarm flag, which suggests that chips which
> support beeping may have a beep control bit for it too. So maybe we
> should define:
> 
> chassis_intrusion_alarm
> chassis_intrusion_beep
> 
> I didn't look at all the datasheets yet to find out whether any chip
> actually implements this, but this doesn't sound unreasonable.
> 
>>> It's not totally clear whether clearing should be done by writing 0 or
>>> 1. 0 is more respectful of traditional sysfs semantics that you should
>>> be able to read back what you just wrote, so it has my vote.
>>>
>>> drivers
>>> ===>>>
>>> Drivers adm9240, w83792d and w83793 implement this feature in
>>> non-standard ways. They should be converted to the new, standard
>>> interface.
>>>
>>> libsensors
>>> =====
>>>
>>> Either
>>>
>>> SENSORS_FEATURE_CHASSIS_INTRUSION = 0x19
>>> SENSORS_SUBFEATURE_CHASSIS_INTRUSION = SENSORS_FEATURE_CHASSIS_INTRUSION << 8
>>>
>>> or rename SENSORS_FEATURE_BEEP_ENABLE to SENSORS_FEATURE_MISC and
>>>
>>> SENSORS_SUBFEATURE_BEEP_ENABLE = SENSORS_FEATURE_MISC << 8
>>> SENSORS_SUBFEATURE_CHASSIS_INTRUSION = (SENSORS_FEATURE_MISC << 8) + 1
>>>
>>> sensors
>>> ===>>>
>>> Reading the value of the chassis intrusion detection subfeature is done
>>> like for any other subfeature.
>>>
>>> Writing, OTOH, can't be handled the same as writing limits, because we
>>> certainly don't want to clear the flag automatically at lm_sensors
>>> start or restart time. So we could add a dedicated flag to clear the
>>> chassis intrusion detection flag (e.g. "sensors --clear-chassis").
>>>
>>> If anyone has objections or comments, please speak up.
>>>
>> looks good to me, but I wonder if we should not prepare for the case where an 
>> IC has more then one chasis intrusion detection pin.
> 
> The same question has been raised by other reviewers already. I am
> shared between simplicity (we've never seen a system with more than
> one, and there is no obvious scenario) and completeness (who knows...)
> 
> The point which makes me reluctant to go for multiple inputs is how we
> are going to handle clearing them with "sensors". Should "sensors
> --clear-intrusion" clear them all? Or do we need to provide a parameter
> specifying which intrusion detector needs to be cleared? The latter
> seems somewhat overkill in the usual case of a single chassis intrusion
> detector. If we go for the former, we have less control but then
> supporting multiple intrusion detectors is cheap.
> 

IMHO: Just make it clear all, if someone really wants to clear only one he can 
use echo 0 > /sys/....

Regards,

Hans

_______________________________________________
lm-sensors mailing list
lm-sensors@lm-sensors.org
http://lists.lm-sensors.org/mailman/listinfo/lm-sensors