UI_ABS_SETUP(9)

🌸 UI_ABS_SETUP — the kernel API manual, but make it make sense 🌸

okay so bestie, welcome to the Kernel API Manual page for UI_ABS_SETUP 💅 this one's a kernel-level ioctl situation, so grab your iced coffee and let's get into it ✨

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✨ NAME ✨

UI_ABS_SETUP — literally just: set absolute axis information for the device you're about to set up 🎀

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✨ SYNOPSIS ✨

UI_ABS_SETUP

that's it. that's the whole synopsis. iconic, honestly 👑

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✨ DESCRIPTION ✨

okay so this ioctl sets one absolute axis information for the input device that's about to be created 🦋 it supersedes the old struct uinput_user_dev method — you know, the ancient one that wrote part of this data plus the content of UI_DEV_SETUP via write. we've moved on, we're thriving 🌈

The ioctl takes a struct uinput_abs_setup object as its argument, no cap. The fields of that object are:

• code — the corresponding input code associated with this axis (ABS_X, ABS_Y, etc...) 👀
• absinfo — see struct input_absinfo for the description of this field. This field gets copied unchanged into the kernel for the specified axis, fr fr. And here's the slay part: if the axis isn't enabled via UI_SET_ABSBIT, this ioctl will enable it for you 💖

This ioctl can be called multiple times and it will just overwrite previous values. no drama, no hard feelings 🌸

⚠️ if this ioctl fails with -EINVAL, it's recommended that you use the old uinput_user_dev method via write as a fallback — that's for when you're running on an old kernel that doesn't support this ioctl. backwards compatibility queen 🫶

And now the error vibes, because we respect them:

• -EINVAL — if it's not supported, or if you passed incorrect values 🙈
• -ENOMEM — if the kernel runs out of memory 😭
• -EFAULT — if the passed uinput_setup object cannot be read/written 💀

⚠️ big one: if this call fails, partial data may have already been applied to the internal device. so like... not a clean rollback. be aware, bestie.

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✨ SEE ALSO ✨

• Kernel file ./include/uapi/linux/uinput.h
• UI_DEV_SETUP(9)
• UI_GET_SYSNAME(9)
• UI_GET_VERSION(9)

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and that's the page!! 🧚 from the kernel files at ./include/uapi/linux, dated October 2026 — go forth and set those absolute axes, you absolute main character 🎀✨💜