intel_hfi_online(9)

hey bestie 💖 welcome to intel_hfi_online(9) from the Kernel API Manual — this is the glow-up guide for turning HFI on for a CPU, and it’s giving “small function, package-level responsibilities” energy ✨

🎀 NAME 🎀

• intel_hfi_online — Enable HFI on @cpu 💅

🌸 SYNOPSIS 🌸

void intel_hfi_online (unsigned int cpu );

🦋 ARGUMENTS 🦋

• cpu — the CPU in which the HFI will be enabled. That’s the one, bestie. 🫶

✨ DESCRIPTION ✨

okay so enable the HFI to be used in cpu. That’s the whole assignment. 💖

The HFI is enabled at the package level. Like, it’s a package-wide situation, not a solo-CPU moment. 👑

The first CPU in the package to come online does the full HFI initialization — she’s the main character doing the setup, no cap. Subsequent CPUs will just link themselves to the HFI instance of their package. Lowkey iconic teamwork. 🦋

This function is called before enabling the thermal vector in the local APIC in order to ensure that cpu has an associated HFI instance when it receives an HFI event. Timing is literally everything here, fr fr. ⭐

👑 SEE ALSO 👑

• Kernel file: ./drivers/thermal/intel/intel_hfi.c 📁
• struct hfi_cpu_data(9) 🧚
• struct hfi_hdr(9) 🧚
• struct hfi_instance(9) 🧚
• struct hfi_features(9) 🧚
• struct hfi_cpu_info(9) 🧚
• intel_hfi_offline(9) 💅

cute lil’ sign-off: this page comes from the source/version path ./drivers/thermal/intel and is dated October 2026 — mwah, go enable that HFI bestie 💅🎀✨