efi_crc32(9)

💅 efi_crc32(9) — the EFI-flavoured crc32, bestie

okay so this is a page from the Kernel API Manual, and honestly? it's a little baddie of a function. let's get into it ✨

---

🌸 NAME 🌸

efi_crc32 — it's giving "EFI version of crc32 function", and that's literally the whole vibe 🎀

---

🦋 SYNOPSIS 🦋

u32 efi_crc32 (const void *buf , unsigned long len );

no cap, that's the whole signature. she's short, she's sweet, she takes two things and gives you back a u32. periodt 💅

---

✨ ARGUMENTS ✨

• buf — the buffer you want the crc32 of, like that's the whole thing she's chewing on 🫶
• len — the length of buf. yes bestie, you do have to tell her how long it is, she's not psychic 😭

---

💖 DESCRIPTION 💖

so the tea is: this one returns the EFI-style CRC32 value for buf 🧚 and the way it does it is honestly so specific:

• it uses the little endian Ethernet polynomial (iconic, classic, we love her)
• but it seeds the function with ~0
• and then xor's with ~0 at the end

that's the whole recipe. seed with ~0, cook, xor with ~0. slay 🔥

🍓 now listen, bestie, here's a fun historical lil' detail: the EFI Specification, v1.02, has a reference to Dr. Dobbs Journal, May 1994 — except actually it's in May 1992. yeah. the spec got the date wrong. not me clocking that 💀🙈

---

👑 SEE ALSO 👑

go check out the kernel file ./block/partitions/efi.c, plus all her besties in the group chat 🌈:

• last_lba(9)
• is_pmbr_valid(9)
• read_lba(9)
• alloc_read_gpt_entries(9)
• alloc_read_gpt_header(9)
• is_gpt_valid(9)
• is_pte_valid(9)
• compare_gpts(9)
• find_valid_gpt(9)
• utf16_le_to_7bit(9)
• efi_partition(9)

and also the directory ./block/partitions, because that's where all of this lives 🦋

---

⭐ and that's the page!! one last lil' sign-off, mwah 💜: this one comes from ./block/partitions, dated October 2026, and it's living its best life inside the Kernel API Manual as efi_crc32(9). go forth and checksum, queen 👑✨