dev_change_flags(9)

💅 dev_change_flags(9) — or, how to glow-up your netdev's settings ✨

okay bestie, so this one lives in the Kernel API Manual, and it's genuinely iconic — it's the function that lets you flip a network device's state flags. no cap, it's giving "remote control for your NIC" energy 🎀

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🌸 SYNOPSIS 🌸

int dev_change_flags (struct net_device *dev , unsigned int flags ,
       struct netlink_ext_ack *extack );

like, three args, one int back. simple. clean. slay 💅

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🫶 ARGUMENTS 🫶

• dev — the device. the actual network device you're messing with, a struct net_device *. yes, that one. 👑
• flags — the device state flags. this is the whole vibe check of the call — the flags you want to set. 🦋
• extack — netlink extended ack. the little receipt-machine for netlink errors, a struct netlink_ext_ack *. 📬

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💖 DESCRIPTION 💖

so what does it do? it changes settings on the device based on the state flags you pass in. literally that's the whole thing. 🧚

and here's the little detail that matters — the flags are in the userspace exported format. so like, the same flag layout the userspace side sees. not some secret kernel-only dialect. iykyk 🔥

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⭐ RETURN ⭐

• 0 on success — we love a clean win 💚
• -errno on failure — classic kernel move, negative errno, no surprises 😭

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🌈 SEE ALSO 🌈

okay this list is long and honestly kind of a flex. all of these live in the kernel file ./net/core/dev_api.c, and they're all the sibling functions doing adjacent little jobs:

• dev_change_name(9) — rename arc 🎀
• dev_set_alias(9) — the nickname era
• dev_set_group(9) — group assignment, very "which friend group are you in"
• dev_change_net_namespace(9) — moving to a whole different namespace, main character energy
• dev_change_carrier(9) — carrier signal shenanigans
• dev_change_tx_queue_len(9) — queue length glow-up
• dev_change_proto_down(9) — protocol down state
• dev_open(9) — bring it up
• dev_close(9) — bring it down
• dev_disable_lro(9) — LRO off, bye 👋
• dev_set_promiscuity(9) — the promiscuous counter, no judgement
• dev_set_allmulti(9) — allmulti counter
• dev_set_mac_address(9) — new MAC, new me 💅
• netdev_state_change(9) — announce that state changed, fr fr

no cap bestie, if you're touching flags you're probably also touching at least three of these. the netdev API is a whole ecosystem and you're just living in it 🦋

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and that's the whole page!! written from the kernel source tree at ./net/core, dated October 2026, and archived under the manual name dev_change_flags(9) — mwah, go flip some flags 💜✨