Originally published last summer were patches from Intel for the Linux kernel to introduce [1]a PCI Express bandwidth controller Linux driver to provide a PCIe cooling mechanism via bandwidth reduction to devices in order to prevent thermal issues. One year later this driver continues to be worked on and today brought the eighth iteration of these patches.

The PCIe bandwidth controller driver with associated PCIe cooling driver code is to limit the PCIe link speed when needed for thermal reasons. For now the cooling approach is just by manipulating the PCIe link speed but the PCIe link width may be another pursuit at least for PCI Express 6.0 and beyond where there is a mechanism for that control.

With the latest bandwidth controller driver patches, the CONFIG_PCIE_BWCTRL build time option is dropped in favor of just gating it via the CONFIG_PCIEPORTBUS option. Plus some other minor fixes.

After being worked on the past year, it's looking like this code might be settling down and finally ready for the mainline kernel soon. Having to limit the PCIe link speed for thermal reasons is no fun, but should your system(s) be enduring such environments, the v8 driver code for review can be found on the [2]Linux power management mailing list .



[1] https://www.phoronix.com/news/Intel-PCIe-Bandwidth-Thermal

[2] https://lore.kernel.org/linux-pm/20241009095223.7093-1-ilpo.jarvinen@linux.intel.com/