drm_ioctl_compat_t(9)

💅 drm_ioctl_compat_t(9) — from the Kernel API Manual, bestie 🎀

okay so this is a kernel API manual page, and honestly? it's a short one but it's lowkey iconic for what it is. let's get into it ✨

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🌸 NAME 🌸

drm_ioctl_compat_t — the compatibility DRM ioctl function type. periodt. that's the whole name. short king energy 👑

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✨ SYNOPSIS ✨

here's the literal signature, copy it exactly, no improvising:

typedef int drm_ioctl_compat_t (struct file *filp , unsigned int cmd ,
       unsigned long arg );

it's giving "one typedef, zero drama" 💅

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🦋 ARGUMENTS 🦋

• filp — the file pointer. that's it, that's the whole vibe 🫶
• cmd — the ioctl command code. the actual "what do you want me to do" of it all ✨
• arg — the DRM file this ioctl was made on 🌈

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💖 DESCRIPTION 💖

so like, it's just a typedef — that's it, no cap. its entire purpose in life is making it easier to declare an array of compatibility handlers, which is honestly such a humble main character move 😭

and here's the tea you actually need: new drivers shouldn't screw up the structure layout for their ioctl structures — and because they shouldn't be doing that, they never need this. so if you're writing a shiny new driver, this typedef is not for you, bestie. it's a legacy-handler situation 🙈 🔥

lowkey important: the manual doesn't say new drivers can't need it — it says they shouldn't screw up the layout, and hence never need it. that's the phrasing, keep it in your heart 💜

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🌟 SEE ALSO 🌟

go read these, they're the friend group:

• Kernel file ./include/drm/drm_ioctl.h
• drm_ioctl_t(9)
• enum drm_ioctl_flags(9)
• struct drm_ioctl_desc(9)
• DRM_IOCTL_DEF_DRV(9)

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and that's the pageeee! 🎉 this one lives under ./include/drm, dated October 2026 — mwah, slay, go read the header file next, iykyk 💅🏼💖✨