Package C-States, Render standby

Moritz

Is there any specific reason that CPU C-State and Package C-State is limited to C1 by default in BIOS? In addition, the Render Standby (RC6) of the GPU has been turned off?

This would gain me the other 2-3 Watts I was looking for at the beginning.

Javier Arteaga

Hi moe,

The intention is to workaround a hardware bug in the SoC that may cause the processor to hang when switching back from deep sleep states.
See erratum CHT45 in this document: http://www.intel.com/content/www/us/en/processors/atom/atom-z8000-spec-update.html

This BIOS setting can be overridden by the operating system, in any case. On Linux, for example, the intel_idle module will not honor this setting unless the intel_idle.max_cstate kernel parameter is set to 0.

Regards

DCleri

I would like to add that we are looking to include the CHT45 fix in the next UEFI BIOS release.

Moritz

Thanks for clarifying this! Looking forward for the fix, but so far i'm not running into any trouble.

Regards
moe