tld_create_key(9)

💖 tld_create_key(9) — a Kernel API Manual moment 💖

okay bestie, gather round, because this one is from the Kernel API Manual and it's lowkey iconic. it's tld_create_key(9) and it's literally about making a TLD and getting a key back that's associated with it. slay. let's get into it ✨

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✨ NAME ✨

tld_create_key — create a TLD and return a key associated with the TLD. that's it, that's the vibe 🎀

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🦋 SYNOPSIS 🦋

tld_key_t tld_create_key (const char *name , size_t size );

look at her. so clean. so main character. 💅

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🌸 ARGUMENTS 🌸

• name — the name the TLD 🏷️ (yes, that's exactly what the manpage says, don't come for me)
• size — the size of the TLD 📏

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💜 DESCRIPTION 💜

so what does she actually do? she returns an opaque object key. that's the whole thing. iconic behaviour, no notes.

now, please don't just rawdog it and assume it worked — use tld_key_is_err or tld_key_err_or_zero to check if the key creation actually succeeded. vibe check your return value, fr fr 😭

once you've got your key, pass it to tld_get_data to get a pointer so you can locate the TLD. and plot twist — bpf programs can also fetch the same key by name. iykyk 🫶

⚠️ important bestie moment: only use tld_create_key when a TLD genuinely needs to be created dynamically — like when the name is not known statically, or a TLD needs to be created conditionally. don't be out here creating things dynamically for no reason, that's not the move 🙈

and here's the memory tea ☕: an additional TLD_DYN_DATA_SIZE bytes are allocated per-thread to accommodate TLDs created dynamically with tld_create_key. since only a user page is pinned to the kernel, when TLDs created with TLD_DEFINE_KEY uses more than TLD_PAGE_SIZE - TLD_DYN_DATA_SIZE, the buffer size will be limited to the rest of the page. so like, space is finite, the math is mathing, plan accordingly 💀

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🎀 SEE ALSO 🎀

• kernel file ./tools/testing/selftests/bpf/prog_tests/task_local_data.h 📁
• TLD_DEFINE_KEY(9)
• tld_get_data(9)
• tld_free(9)

go read those too, bestie, knowledge is free and it's giving study session 🌈

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and that's the page!! brought to you by the fine folks over at ./tools/testing/selftests/bpf/... — the source/version line situation — dated October 2026. periodt. 💅✨🎀🦋💖