dev_set_hwtstamp_phylib(9)

🌸 NAME 🌸

dev_set_hwtstamp_phylib — okay so this is the one that changes the hardware timestamping of a NIC, or of an attached phylib PHY. Like, it flips the timestamping situation. 💅

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✨ SYNOPSIS ✨

int dev_set_hwtstamp_phylib (struct net_device *dev , struct
kernel_hwtstamp_config *cfg , struct netlink_ext_ack *extack );

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🎀 ARGUMENTS 🎀

• dev — the network device. bestie. the NIC in question. 🖥️
• cfg — the timestamping configuration structure. this is where the actual settings live, okurrr 💖
• extack — the Netlink extended ack message structure, and it's literally there for error reporting. so if stuff goes sideways, this is where the tea gets spilled 😭

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🦋 DESCRIPTION 🦋

So this is a helper function, and its whole job is enforcing a common policy. And the policy is giving very much main character energy:

phylib timestamping, if it's available, should take precedence in front of hardware timestamping provided by the netdev. periodt. PHY wins the vibe check, and the netdev-provided hardware timestamping is behind it in line. 👑

But okay, here's the part you actually need to know, because it's lowkey important: if the netdev driver needs to do specific actions even for PHY timestamping to work properly — and the example is literally a switch port must trap the timestamped frames and not forward them — then it must set dev->see_all_hwtstamp_requests. no cap, that's the flag, that's the move. set it or your switch port is out here forwarding frames it should've trapped and the timestamping situation is giving chaos 🙈

fr fr, don't skip the dev->see_all_hwtstamp_requests part. the driver has specific actions to perform? set it. it's not optional, it's the whole point 🫶

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🧚 SEE ALSO 🧚

• Kernel file ./net/core/dev_ioctl.c dev_get_hwtstamp_phylib(9) — the getter to this setter, they're a matched set, iconic duo ⭐
• dev_load(9)
• dev_ioctl(9)

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and that's the whole page bestie, you ate that 💅 this one's from ./net/core, dated October 2026, and it lives in the Kernel API Manual like the little legend it is. go forth and timestamp correctly 🌈🎀✨