ethnl_update_bool(9)

💖 ethnl_update_bool — a.k.a. the ethnl_update_bool(9) page, kernel API manual edition 🎀

okay so bestie, we're in the Kernel API Manual today and this is genuinely one of the cutest little helper functions ever. it's called ethnl_update_bool(9), it lives in ./net/ethtool, and it's here to take a netlink attribute and gently turn it into a real actual bool. no cap. let's get into it ✨

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🌸 NAME 🌸

ethnl_update_bool — updateb bool used as bool from NLA_U8 attribute

(not me copying that typo verbatim btw, it's literally in the original and i'm not about to gaslight you about it 💀)

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🦋 SYNOPSIS 🦋

void ethnl_update_bool (bool *dst , const struct nlattr *attr , bool *mod );

like… she's a void. she gives nothing back. she just does things. main character energy honestly 👑

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💅 ARGUMENTS 💅

• dst — the value to update. this is the bool getting a whole glow-up.
• attr — the netlink attribute with the new value, or null. yes, null is allowed here, she's flexible 🫶
• mod — pointer to a bool used for modification tracking. this one's keeping receipts 📝

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✨ DESCRIPTION ✨

okay so here's the vibe 🌈

Use the bool value from the NLA_U8 netlink attribute attr to set the bool variable pointed to by dst to 0 (if zero) or 1 (if not). literally that simple — zero goes to zero, anything-not-zero goes to one. one job, and she ate 🔥

If attr is null, do nothing. nope. nada. she's not gonna touch it. respect 💅

The bool pointed to by mod is set to true if this function changed the logical value of *dst, otherwise it is left as is. so mod is basically the "did i make a difference today" flag, and if you didn't change anything it just stays exactly how you left it. mood 🎀

lowkey the whole thing is a vibe check on an attribute: null? ignore. zero? 0. not zero? 1. changed? mod says true. unchanged? mod stays as is. periodt.

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🧚 SEE ALSO 🧚

Kernel file ./net/ethtool/netlink.h, plus the whole friend group 🫶:

• ethnl_strz_size(9)
• ethnl_put_strz(9)
• ethnl_update_u32(9)
• ethnl_update_u8(9)
• ethnl_update_u8_u32(9)
• ethnl_update_bool32(9)
• ethnl_update_binary(9)
• ethnl_update_bitfield32(9)
• ethnl_reply_header_size(9)
• struct ethnl_req_info(9)
• ethnl_req_get_phydev(9)
• struct ethnl_reply_data(9)
• struct ethnl_request_ops(9)

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and that's the whole page, bestie — go update some bools responsibly 💖

signed off from ./net/ethtool, October 2026, on the ethnl_update_bool(9) page — mwah 💋