mii_bmcr_encode_fixed(9)

📦 version 7.3.1, in nixpkgs unstable

💅 mii_bmcr_encode_fixed — the Kernel API Manual moment

okay so bestie, welcome to mii_bmcr_encode_fixed(9), part of the Kernel API Manual, and honestly this one is short but it does the thing. Let's get into it 🎀

✨ NAME ✨

mii_bmcr_encode_fixed — encodes fixed speed/duplex settings into a BMCR value. that's it, that's the job, and it does it slayfully 💖

🌸 SYNOPSIS 🌸

u16 mii_bmcr_encode_fixed (int speed , int duplex );

🦋 ARGUMENTS 🦋

  • speed — a SPEED_* value. yep, one of those 🫶
  • duplex — a DUPLEX_* value. also one of those ✨

👑 DESCRIPTION 👑

So what this icon does is encode the speed and the duplex into a single BMCR value. one value. two things going in. it's giving efficiency, fr fr 💅

Speeds 2500, 1000, 100 and 10 Mbps are supported. that's the whole guest list.

Now, the little plot twist: 2500 Mbps gets encoded to 1000 Mbps. not a typo, that's just how it goes 😭

Other speeds — the ones not on the list — get encoded as 10 Mbps. so like, unknown speed? you're getting 10. no cap.

And duplex? Unknown duplex values get encoded to half-duplex. so if it's not a duplex value we recognise, it's going half. periodt 🧚

ngl, if you're passing in something weird, this function has opinions and it will make a decision for you. it's not asking. it's telling 🌈

🔥 SEE ALSO 🔥

Kernel file ./include/linux/mii.h — and honestly the whole friend group, all of them, here we go:

that's the whole group chat, go read them too 💜

okay that's the page!! 🎀 and for the cute sign-off: this one lives under ./include/linux, dated October 2026, and it's mii_bmcr_encode_fixed(9) — kudos to the kernel crew, mwah 💋✨

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