On Tue, Jun 07, 2011 at 03:27:22PM -0400, Jean Delvare wrote:
> Hi Durgadoss, Fenghua and Guenter,
>
> With commit 199e0de7f5df31a4fc485d4aaaf8a07718252ace (hwmon: (coretemp)
> Merge pkgtemp with coretemp), the following piece of code was added to
> the coretemp driver:
>
> +static void update_ttarget(__u8 cpu_model, struct temp_data *tdata,
> + struct device *dev)
> +{
> + int err;
> + u32 eax, edx;
> +
> + /*
> + * Initialize ttarget value. Eventually this will be
> + * initialized with the value from MSR_IA32_THERM_INTERRUPT
> + * register. If IA32_TEMPERATURE_TARGET is supported, this
> + * value will be over written below.
> + * To Do: Patch to initialize ttarget from MSR_IA32_THERM_INTERRUPT
> + */
> + tdata->ttarget = tdata->tjmax - 20000;
>
> I have questions and concerns about this (on top of the fact that this
> side change was not documented and should have been submitted as a
> separate patch, if it is really correct.)
>
> 1* Where does the magic 20°C constant come from? Is this just an
> arbitrary approximation, or is it really correct?
>
> 2* Do all Intel CPUs with DTS really have a target temperature? So far,
> the tempX_max limit (which corresponds to ttarget) was only created
> conditionally, on new CPU models. Older models did not have it. As a
> matter of fact, the documentation file says that the feature is only
> available since Core 2. Please remember that we do NOT want to
> present fake limits to user-space. Any limit exposed to user-space
> should correspond to a real attribute of the CPU (or core.)
>
> 3* Why is the "to do" item not done yet? We have already just made
> significant changes to the coretemp driver, which break user-space
> compatibility to some degree. I don't want to do it again with the
> next kernel version. So if MSR_IA32_THERM_INTERRUPT can be used to
> get a better value for tdata->ttarget, then please let's implement
> it properly right now, for kernel 3.0.
>
> If anyone has comments on this, please speak up.
>
Durgadoss wanted to submit a separate patch to address the "To Do".
I don't know what happened to it.
Guenter
_______________________________________________
lm-sensors mailing list
lm-sensors@xxxxxxxxxxxxxx
http://lists.lm-sensors.org/mailman/listinfo/lm-sensors
