Intel prepares “PFRUT” for Linux 5.17 to allow system firmware update without reboot


Intel’s open source engineers prepared “PFRUT” support for platform firmware runtime updates to allow (U)EFI capsule updates to be made on systems capable without rebooting the system to eliminate downtime.

Intel worked on PFRUT which is now part of the ACPI specification to allow platform firmware components to be updated on the fly without the need for a system reboot. The intent of this is for servers where they need to be “up 100% of the time” and other cases where downtime needs to be kept to an absolute minimum. This set of “pfr_update” drivers for the introduction of Linux 5.17 seems to be primarily designed to be able to update system firmware in case of critical bugs or security issues in a timely manner, without introducing new downtime.

Back in September, I wrote about Intel engineers working on such features for the Linux kernel and around this ACPI specification. At the time, it was called Intel’s “Seamless Update”, probably their trade name. Patches for this new driver just reference it as ACPI PFRUT without calling it Seamless Update, so we’ll see if that branding has changed or if Intel is just trying to keep this ACPI driver completely vendor-neutral.

Another change with this new series of patches is PFRUT where as before it mentioned PFRU…. The “T” added now is for telemetry. As part of this enablement, there is now also a platform firmware runtime telemetry driver. This driver is used to read firmware telemetry data in a standardized way.

This fix Monday introduced the new pfr_update driver and followed by the telemetry pilot. is also added a simple PFRUT tool for the user space to demonstrate firmware updates and telemetry access.

These patches were picked up by the “linux-next” branch of Linux power management, which means they are hardware for the next kernel cycle, which will be Linux 5.17 with this merge window s opening in mid-January.

For those who want more information on Intel’s runtime firmware update, from August is the Intel Management Mode Firmware Runtime Update Specification. We’ll see in the future if desktop systems end up supporting it or are reserved for server-grade hardware only.


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