__arm_smccc_hvc(9)

🌸 __arm_smccc_hvc — Kernel API Manual, section 9 🌸

okay bestie, sit down, we're learning how the kernel literally calls up its firmware today 💅 this is the page for __arm_smccc_hvc(9), and honestly? it's giving "the phone call your whole system depends on" energy 🔥

✨ NAME ✨

__arm_smccc_hvc — make HVC calls. and yeah, @a0-a7 are the arguments you pass in registers 0 to 7 🎀

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✨ SYNOPSIS ✨

void __arm_smccc_hvc (unsigned long a0 , unsigned long a1 , unsigned long a2 , unsigned long a3 , unsigned long a4 , unsigned long a5 , unsigned long a6 , unsigned long a7 , struct arm_smccc_res *res , struct arm_smccc_quirk *quirk );

like, yes, it's void — it doesn't hand you a return value back directly, it hands it back through res 😌 no cap.

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✨ ARGUMENTS ✨

• a0 — -- undescribed -- 🙈 (the docs said nothing, so I say nothing. mystery icon behaviour.)
• a1 — -- undescribed -- 🙈
• a2 — -- undescribed -- 🙈
• a3 — -- undescribed -- 🙈
• a4 — -- undescribed -- 🙈
• a5 — -- undescribed -- 🙈
• a6 — -- undescribed -- 🙈
• a7 — -- undescribed -- 🙈 (the whole squad is undocumented up here, and that's just how it is 🫶)
• res — the result values, fresh out of registers 0 to 3 ✨
• quirk — points to an arm_smccc_quirk, or NULL when no quirks are required. NULL = no special behaviour, we're being normal today 🎀

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✨ DESCRIPTION ✨

so the way this works 👑 — this function is what you use to make HVC calls following SMC Calling Convention. literally its whole job.

the content of the supplied param gets copied to registers 0 to 7 prior to the HVC instruction 🦋 then, on return from the HVC instruction, the return values are updated with the content from register 0 to 3. in-and-out, clean, iconic.

and then there's the optional quirk structure — it provides vendor specific behavior 💫 iykyk.

ngl if you're reaching for the quirk pointer, something is vendor-specific and probably weird. that's the vibe, bestie. that's the whole reason it exists.

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✨ SEE ALSO ✨

• Kernel file ./include/linux/arm-smccc.h
• arm_smccc_1_1_get_conduit(9)
• arm_smccc_get_version(9)
• arm_smccc_get_soc_id_version(9)
• arm_smccc_get_soc_id_revision(9)
• struct arm_smccc_res(9)
• struct arm_smccc_1_2_regs(9)
• arm_smccc_1_2_hvc(9)
• arm_smccc_1_2_smc(9)
• struct arm_smccc_quirk(9)
• __arm_smccc_smc(9)

go read __arm_smccc_smc(9) too, fr fr, it's the sibling 👯‍♀️

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and that's the page!! 🥳 this little gem lives in ./include/linux and it's stamped October 2026 — so mark your calendars, bestie, the future is now 💖 stay hydrated, keep your registers straight, and slay ✨🎀🦋