kmsg_dump_register(9)

💖 kmsg_dump_register(9) 💖

Okay bestie, so this one lives in the Kernel API Manual, and it is exactly what it sounds like: registering a kernel log dumper. Like, the kernel keeps a diary (the log), and this is how you sign up a little helper that gets to read it out loud when things go 💀. Iconic behaviour, honestly.

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✨ NAME ✨

kmsg_dump_register — register a kernel log dumper.

🫶 SYNOPSIS 🫶

int kmsg_dump_register (struct kmsg_dumper *dumper );

🎀 ARGUMENTS 🎀

• dumper — a pointer to the kmsg_dumper structure. That's your little registration form, basically. Fill it in, hand it over. 🦋

🔥 DESCRIPTION 🔥

So what this does: it adds a kernel log dumper to the system. That's the whole vibe check. ✅

And here's the important part, bestie, so listen — the dump callback inside that structure will be called when the kernel oopses or panics, and it must be set. Like, not optional. If it's not set, that's a problem. No cap. 😭

Return value? It returns zero on success and -EINVAL or -EBUSY otherwise. So zero = slay, anything else = check yourself before you wreck yourself. 💅

🌈 SEE ALSO 🌈

The kernel file ./kernel/printk/printk.c is where the lore lives, and the whole printk console squad is linked here — honestly an entire friend group:

• console_list_lock(9), console_list_unlock(9), console_srcu_read_lock(9), console_srcu_read_unlock(9)
• console_lock_spinning_enable(9), console_lock_spinning_disable_and_check(9), console_trylock_spinning(9)
• printk_parse_prefix(9), add_preferred_console(9), match_devname_and_update_preferred_console(9)
• console_suspend_all(9), console_cpu_notify(9)
• console_lock(9), console_trylock(9), console_unlock(9), console_flush_on_panic(9)
• printk_kthreads_shutdown(9), console_force_preferred_locked(9)
• pr_flush(9), wake_up_klogd(9), defer_console_output(9), printk_trigger_flush(9), printk_timed_ratelimit(9)
• kmsg_dump_unregister(9), kmsg_dump_desc(9), kmsg_dump_get_line(9), kmsg_dump_get_buffer(9), kmsg_dump_rewind(9)
• console_try_replay_all(9)
• __printk_cpu_sync_wait(9), __printk_cpu_sync_try_get(9), __printk_cpu_sync_put(9)

Like, the whole extended cast. Go read them, iykyk. 📚✨

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Fr fr though — that callback must be set before you register. The kernel does not do "oops, forgot it" energy. 🙈

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Mwah, that's the page! 🍓 This little gem ships from ./kernel/printk, dated October 2026, and it's giving very much "printk bestie" main character energy the whole way through. Catch you on the next man page! 💜🧚