STRUCT INPUT_KEYMAP_ENTRY(9)

💅 struct input_keymap_entry(9) — the kernel manual, but make it make sense

okay bestie, so this is a page from the Kernel API Manual, and it's about one lil struct named struct input_keymap_entry that the kernel uses to talk about keymaps. she's not a big celebrity struct, but she's iconic in her own way 🎀

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✨ NAME ✨

struct input_keymap_entry — the struct that's used by the EVIOCGKEYCODE/EVIOCSKEYCODE ioctls. that's literally her whole job, and she does it flawlessly 💖

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🦋 SYNOPSIS 🦋

here's the whole glow-up, exactly as she appears in the wild:

struct input_keymap_entry {
  #define INPUT_KEYMAP_BY_INDEX   (1 << 0);
    __u8 flags;
    __u8 len;
    __u16 index;
    __u32 keycode;
    __u8 scancode[32];
 };

like, she's serving struct realness. 32 bytes of scancode buffer. no notes. periodt ✨

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🌸 Members 🌸

okay so these are the fields, and honestly each one is a lil main character:

• flags — this is where you tell the kernel how she should handle the request. for example, setting the INPUT_KEYMAP_BY_INDEX flag indicates that the kernel should perform the lookup in the keymap by index instead of by scancode. so like, index girlies rise 🫶
• len — the length of the scancode that resides in the scancode buffer. yes, she's literally just telling you how long the thing is. queen of clarity 💅
• index — the index in the keymap. this one may be used instead of scancode. she's the alternative route, the backup plan, the understudy that sometimes gets the lead role 😭
• keycode — the key code assigned to this scancode. this is the whole point of the operation ngl 🔥
• scancode — scancode represented in machine-endian form. not network endian, not vibe endian, machine endian. write that down bestie 📝

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💜 Description 💜

okay so boom — this structure is used to retrieve and modify keymap data. that's the tea ☕

users have the option of performing a lookup either by the scancode itself or by index in the keymap entry. two paths, same destination, choose your fighter ✨

and EVIOCGKEYCODE will also return the scancode or the index — depending on which element was used to perform the lookup. so she mirrors your energy right back at you. reciprocal queen 👑

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🌈 SEE ALSO 🌈

the whole friend group, no cap:

• Kernel file ./include/uapi/linux/input.h struct input_absinfo(9)
• EVIOCGMTSLOTS(9)
• EVIOCGMASK(9)
• EVIOCSMASK(9)
• struct ff_replay(9)
• struct ff_trigger(9)
• struct ff_envelope(9)
• struct ff_constant_effect(9)
• struct ff_ramp_effect(9)
• struct ff_condition_effect(9)
• struct ff_periodic_effect(9)
• struct ff_rumble_effect(9)
• struct ff_haptic_effect(9)
• struct ff_effect(9)

ngl go read those too, the lore is deep and the structs are lowkey everything 🧚

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and that's the page, bestie!! this one came from ./include/uapi/linux, dated October 2026 — so yeah, mark your calendars, screenshot it, send it to the group chat 💌 stay slay, stay machine-endian 💅✨