Summary

The Talos kernel currently has CONFIG_POWERCAP disabled, which prevents users from setting Intel RAPL power limits (PL1/PL2) via sysfs at runtime.

# CONFIG_POWERCAP is not set

Only CONFIG_PERF_EVENTS_INTEL_RAPL=y is enabled, which allows reading energy counters but not setting power limits.

Use Case

Intel's 13th/14th generation processors (e.g., i9-13900K, i9-14900K) have documented stability issues when running with unlimited power limits. Intel's official recommendation is to set conservative power limits:

• PL1 (long-term): 125W
• PL2 (short-term): 188-253W

Currently, Talos users must configure these limits in BIOS, which:

• Requires physical/IPMI access
• Can't be managed declaratively via machine config
• Doesn't allow runtime adjustment

Requested Change

Enable in kernel/build/config-amd64 and config-arm64:

CONFIG_POWERCAP=y
CONFIG_INTEL_RAPL=m

This would expose /sys/class/powercap/intel-rapl/ and allow setting power limits via Talos machine.sysfs:

machine:
  sysfs:
    devices.virtual.powercap.intel-rapl.intel-rapl:0.constraint_0_power_limit_uw: "125000000"
    devices.virtual.powercap.intel-rapl.intel-rapl:0.constraint_1_power_limit_uw: "253000000"

Additional Context

• Related projects like Kepler (CNCF) and Scaphandre use RAPL interfaces for power monitoring in Kubernetes
• The powercap subsystem is lightweight and only exposes sysfs interfaces when RAPL-capable hardware is present
• This would also benefit users wanting to monitor/limit power consumption in homelab or edge deployments

Environment

• Talos version: v1.11.2
• Kernel: 6.12.57-talos
• Hardware: Intel i9-14900K