check_telem_request(9)

💅 check_telem_request(9) — bestie edition

okay so this is a page from the Kernel API Manual and honestly? it's a little bouncer at the club door of your kernel. it's check_telem_request, and its whole job is vibe-checking stuff coming in from userspace. let's get into it 🫶

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✨ NAME ✨

check_telem_request — make sure a request coming from userspace is actually valid, no cap.

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🌸 SYNOPSIS 🌸

int check_telem_request (struct wilco_ec_telem_request *rq , size_t size
);

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🎀 ARGUMENTS 🎀

• rq — the request buffer that got copied over from userspace. this is the thing we're inspecting 💅
• size — how many bytes got copied from userspace. literally the byte count, nothing spicier than that.

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🔥 RETURN 🔥

• 0 — valid, we're slaying, come on in ✨
• -EINVAL — bad command, OR the reserved byte is non-zero. either way, not it. 🙈
• -EMSGSIZE — the request is too long bestie, it's giving overstuffed.

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🦋 DESCRIPTION 🦋

okay so the whole reason this function exists: we highkey do not want to let userspace send arbitrary telemetry commands to the EC. like, absolutely not, no thank you 💀. so before anything goes through, we check a few things. and by "a few things" i mean:

1. The request follows the format of struct wilco_ec_telem_request. gotta match the shape, iykyk 🧚
2. The supplied command code is one of the allowlisted commands. if it's not on the list, it's not getting in — periodt 👑
3. The request only contains the necessary data for the header and arguments. no extra random junk snuck into the payload, we're not doing that 🌸

three checks, all iconic, all necessary. the way that this function just quietly protects the whole kernel… main character energy honestly ⭐

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🌈 SEE ALSO 🌈

• Kernel file ./drivers/platform/chrome/wilco_ec/telemetry.c
• struct wilco_ec_telem_request(9)
• struct telem_device_data(9)
• struct telem_session_data(9)
• telem_open(9)
• telem_device_free(9)
• telem_device_probe(9)

go read those too, they're all part of the same friend group 🫶

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and that's the page!! sourced from ./drivers/platform/chrome/wilc... and dated October 2026 — ty for coming to my ted talk, mwah 💖🎀