e1000_platform_pm_pch_lpt(9)

📦 version 7.3.1, in nixpkgs unstable

💅 e1000_platform_pm_pch_lpt(9) — from the Kernel API Manual, bestie 🎀

okay so picture this: you're deep in the kernel, section 9, and the manual page you've got open is literally called e1000_platform_pm_pch_lpt(9). yes that's a mouthful, no we're not shortening it, it's iconic and we respect it. let's get into it ✨

🌸 NAME 🌸

e1000_platform_pm_pch_lpt — sets the platform power management values. that's the whole vibe. she does one thing and she does it well 💅

✨ SYNOPSIS ✨

s32 e1000_platform_pm_pch_lpt (struct e1000_hw *hw , bool link );

look at her. s32 in, s32 out, two args, no drama 🫶

🎀 ARGUMENTS 🎀

  • hw — pointer to the HW structure, aka the whole hardware situation. bestie needs to know what she's working with 💖
  • link — a bool indicating link status. basically: is the link up or not. that's the tea ☕

🦋 DESCRIPTION 🦋

okay so what she actually does 👑 — she sets the Latency Tolerance Reporting (LTR) values for the "PCIe-like" GbE MAC in the Lynx Point PCH.

and how does she decide those values? based on the Rx buffer size and the link speed — but only when link is up. and even then, those values must not exceed the maximum latency supported by the platform (read that again, it's important, no cap 🫣). if the link is not up, she just specifies that there is no LTR requirement. simple as that ✨

now here's the part that's lowkey fascinating and you need to hear it 🌈 — unlike true-PCIe devices, which set the LTR maximum snoop/no-snoop latencies in the LTR Extended Capability Structure inside the PCIe Extended Capability register set, on this device LTR is set a completely different way:

  • she writes the equivalent snoop/no-snoop latencies into the LTRV register in the MAC, and
  • she sets the SEND bit, which fires off an Intel On-chip System Fabric sideband (IOSF-SB) message to the PMC 💌

it's giving "not like other devices" and honestly? slay 🔥

💜 SEE ALSO 💜

the kernel file, first of all:

  • Kernel file ./drivers/net/ethernet/intel/e1000e/ich8lan.c

and now the full friend group, everybody say hi 👋 (yes, all of them, we're not leaving anyone out, that would be mean):

and that's the whole page, bestie 🍓 every flag, every friend, no crumbs left behind 💀

kisses and goodnight 😭💖 — this one came out of the kernel source at ./drivers/net/ethernet/intel/e... and is dated October 2026, and yes she's still signed e1000_platform_pm_pch_lpt(9) because legends never change their name 👑✨🧚

📦 where this page comes from