efi_get_random_bytes(9)

🦋 efi_get_random_bytes(9) — kernel api manual, bestie edition 🦋

okay so real talk, this one's from the Kernel API Manual and it's genuinely so useful, no cap. it's efi_get_random_bytes, and it's giving "randomness but make it firmware" 💅.

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✨ NAME ✨

efi_get_random_bytes — fill a buffer with random bytes 🎲✨

like, you hand it a buffer, it fills it with random bytes. that's the whole vibe. iconic honestly.

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🌸 SYNOPSIS 🌸

efi_status_t efi_get_random_bytes (unsigned long size , u8 *out );

that's it, that's the whole signature 🫶. two arguments, one status code back. clean.

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🎀 ARGUMENTS 🎀

• size — the size of the buffer, bestie. how many bytes you're asking for. unsigned long, so go off.
• out — the caller allocated buffer that receives the random bytes 💖. a lil heads up: you allocate it, this function just fills it. so don't come crying if you handed it unallocated memory, okay? 🙈

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⭐ DESCRIPTION ⭐

so here's the tea ☕: this call will fail if either of these two things is true:

1. the firmware does not implement the EFI_RNG_PROTOCOL 😭 — like, no RNG protocol, no random bytes, that's the rules.
2. there are not enough random bytes available to fill the buffer 💀 — you asked for more randomness than the firmware can provide, and it's not gonna fake it for you.

literally either one and the call fails. not a vibe, but like, at least it tells you via the return value instead of silently handing you bad randomness 🌸.

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👑 RETURN 👑

a status code ✨. that's it. that's the whole return section. go check it, bestie, please 🙏.

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🌈 SEE ALSO 🌈

• kernel file ./drivers/firmware/efi/libstub/random.c — the source, if you wanna read the actual code 🧚
• efi_random_get_seed(9) — the sibling function, go say hi 🫶

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lowkey a reminder from your girl: if this fails, you do not have random bytes. don't pretend you do. that's how you get cursed crypto 💀🔐

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and that's the whole page, bestie!! this one came from ./drivers/firmware/efi/libstub, dated October 2026, and if you made it this far, you're literally the main character of the kernel api manual 💖👑✨