I was wondering if there has been any further development of accessing the processor’s thermal sensors on the Developerbox from userland. We are interested in using the Developerbox in a somewhat unique configuration and were hoping we could a) remove the heatsink (necessitating us monitoring the temperature), and b) possbily reduce the clock frequency. It turns out that the normal methods for doing this aren’t supported in the kernel yet. CPUpower and lm-sensors do not apper to be supported by the board. According to several rumors, there are 7 thermal sensors on the processor itself. However, aside from some mention of using them in “secureland” (i.e. Trusted Execution Environment or TEE) for possible use as entropy sources, I can’t seem to find any information out about the thermal sensors.I can’t seem to find a good datasheet or info on this, and haven’t heard back when I contacted Socionext using their online form.
This leads me to ask the following questions here (in hopes that someone can answer them):
Does the Socionext self-throttle? Most modern CPUs have some form of thermal throttling and voltage protection. The Raspberry Pi 3 has self-throttling capabilities which I believe uses the same core (I know that particular SOC implementations vary by vendor, I’m just trying to find information on this subject). What we’d really like to do is remove the heatsink and run the CPU without the heatsink for some testing, but we’re very hesitant to do that if this will damage the chip.
Is there a way to change the clock frequency of the CPU? I’d like to underclock it to reduce the heat generated? again, cpufreq/cpupower don’t seem supported, and we’d like to run it at a lower frequency from boot time anyways. Looking over the EDK2 source doesn’t seem to yield any insight into this, but I may be looking in the wrong place.
Any help would be appreciated!