udp4_hwcsum(9)

📦 version 7.3.1, in nixpkgs unstable

💖 udp4_hwcsum(9) 💖

okay bestie, welcome to the udp4_hwcsum page — it's a Kernel API Manual situation, and honestly? she's short, she's sweet, she's a whole vibe. sit down, sip ur drink 🍓

✨ NAME ✨

udp4_hwcsum — the girl who handles outgoing HW checksumming. that's it. that's the job. no cap 💅

🌸 SYNOPSIS 🌸

void udp4_hwcsum (struct sk_buff *skb , __be32 src , __be32 dst );

literally that's the whole signature, copy it exactly, don't be weird about it 🫶

🦋 ARGUMENTS 🦋

  • skb — a sk_buff that's holding ur filled-in UDP header. and listen: the checksum field must be zeroed out before you hand her over. zeroed. out. that's not a suggestion, that's the rule 🙈
  • src — the source IP address (__be32, iconic).
  • dst — the destination IP address (__be32, also iconic).

🎀 SEE ALSO 🎀

the kernel file ./net/ipv4/udp.c says hi 👋 and also these besties:

go read them, iykyk 📚✨

ngl bestie, the one thing u cannot fumble: that checksum field in skb needs to be zeroed out before this function does its thing. main character energy requires preparation 💀

and that's the page! mwah 💋 this little gem lives in ./net/ipv4, dated October 2026, and yes it's still called udp4_hwcsum(9) — slay, stay iconic, periodt 👑🌈⭐

📦 where this page comes from