2014/1/18 Jean Delvare <khali@xxxxxxxxxxxx>: > Hi Martin, Hi Jean, >> Offset values are by default not 0, > > It is possible that your BIOS does the right thing and presets the > offsets as appropriate. That's right. Default it sets it to 72, so to increase with 10 I have to set to 82. >> does lm_sensors init script reset >> offset values to default when removed from sensors.conf?, > > The lm_sensors init script will typically run "sensors -s" when > starting the service. When stopping the service, it shouldn't change any > setting. "sensors -s" applies all relevant "set" statements in your > sensors.conf configuration files, taking offsets and compute statements > into account. I checked the gentoo init script and yes, it also does sensors -s. However, it doesn't reset values to the BIOS settings (I guess it cannot retrieve the BIOS settings). So when removing a setting in sensors.conf and using the init script, will not reset the removed setting to BIOS value. >> should I >> compile sensor drivers as modules? (currently they are in the kernel, >> so my init script fails when it tries to reload the modules), > > The init script (and sensors-detect until very recently) assumes that > every driver is a module, so this isn't surprising. Some work is still > needed to ensure a smooth user experience with monolithic kernels. I'm > fixing things slowly in this area, but this isn't a priority. Although it doesn't change anything (except that the init script doesn't warn anymore) I have recompiled the kernel to use modules. >> sometimes I get negative values for _input when I switch from compute >> to offset statement, why does compute +10 add 20 to reported values? > > It shouldn't. This might be an unexpected effect of conflicting set > statements, or offset and compute formula being applied to the same > temperature input, or a bug somewhere. I can't really say without more > details from you: complete configuration section from your chip > from /etc/sensors3.conf and any relevant configuration file > under /etc/sensors.d, output of "sensors", output of "sensors > -c /dev/null", output of "sensors -u". I can explain negative values: BIOS sets offset to 72, so when set to 10 it will decrease by 62 instead of adding 10 :-) >> Actually, I think my most important question is: how does the compute >> statement work? > > Originally the driver gets the raw temperature value reported by the > sensor. Then it applies the offset and presents the result to > user-space (through a sysfs attribute.) Libsensors gets that value and > applies the first half of the compute formula for this channel, and > presents the result to the user. > > The second half of the compute formula should always be the inverse > function of the first half, and is applied by libsensors to the > matching set statements. > > Let's take an example. You have a temperature sensor (temp1) which > reports a raw value of 50°C. If temp1_offset is defined as +5°C, the > driver will report temp1_input as 55°C. > > If you happen to have a compute formula for temp1 such as: > > compute temp1 @+10, @-10 > > then "sensors" will display a temp1 input value of 65°C. The compute > formula applies to the limits as well, so if for example the driver > reported the min limit as 10°C and the max limit as 60°C, "sensors" > will show 20°C and 70°C as the limits instead. > > In practice you typically use the offset attribute _instead of_ the > compute formula (assuming you only have to apply an offset), because it > is more efficient. Ah! Finally.. it all makes sense now :-) I believe that I have a configuration file that is worth to be put on the trac/wiki. Just one issue.. where can I register for trac access? Regards, Martin _______________________________________________ lm-sensors mailing list lm-sensors@xxxxxxxxxxxxxx http://lists.lm-sensors.org/mailman/listinfo/lm-sensors
