tpm2_pcr_extend(9)

🦋 tpm2_pcr_extend(9) — the Kernel API Manual glow-up 🦋

okay bestie, so this is tpm2_pcr_extend from the kernel's TPM corner of the world, and it's literally the function that extends a PCR value. that's the whole vibe. it lives in the Kernel API Manual and ngl it's kind of iconic in a "quietly load-bearing security primitive" way 👑

---

🎀 NAME 🎀

tpm2_pcr_extend — extend a PCR value ✨

like, that's it, that's the name. short, sweet, ate 💅

---

🌸 SYNOPSIS 🌸

int tpm2_pcr_extend (struct tpm_chip *chip , u32 pcr_idx , struct
tpm_digest *digests );

she takes three things and returns an int, no cap 🫶

---

💖 ARGUMENTS 💖

• chip — the TPM chip you wanna use. your main character hardware, basically 🖥️
• pcr_idx — the index of the PCR. you gotta tell her which PCR, she's not a mind reader 🙈
• digests — the list of pcr banks and their corresponding digest values that you want to extend. it's giving "bring the whole group chat," fr fr 🍓

---

⭐ RETURN ⭐

same as with tpm_transmit_cmd. that's the whole answer — she's delegating, and honestly? respect 💀

---

🌈 SEE ALSO 🌈

kernel file ./drivers/char/tpm/tpm2-cmd.c — plus the whole friend group, and yes they're all invited:

• tpm2_calc_ordinal_duration(9)
• tpm2_pcr_read(9)
• tpm2_get_random(9)
• tpm2_flush_context(9)
• tpm2_get_tpm_pt(9)
• tpm2_shutdown(9)
• tpm2_do_selftest(9)
• tpm2_probe(9)
• tpm2_startup(9)
• tpm2_auto_startup(9)

---

lowkey a little reminder that this is a kernel function signature, so all those types and pointers are exactly as written — don't go "fixing" the spacing, bestie, it's character-for-character correct 😭

---

and that's the page!! 💜 brought to you from ./drivers/char/tpm, dated October 2026, and yeah — this whole thing is tpm2_pcr_extend(9), one hundred percent. slay, go extend some PCRs responsibly 🔥👑