fb_set_cmap(9)

💖 fb_set_cmap(9) — like, the kernel API manual page, bestie 💖

okay so before we even get into it: this is a page from the Kernel API Manual (yes, the (9) section, that's the kernel-internals girlies) and it's all about one tiny function that does one very specific job. let's get into it ✨

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🌸 NAME 🌸

fb_set_cmap — it sets the colormap. that's it. that's the whole vibe. 💅

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🦋 SYNOPSIS 🦋

int fb_set_cmap (struct fb_cmap *cmap , struct fb_info *info );

look at her. two args, returns an int. iconic. copy it exactly like that, spaces and all, don't @ me 🎀

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👑 ARGUMENTS 👑

• cmap — the frame buffer colormap structure 💖 this is the actual color situation you're handing over.
• info — the frame buffer info structure ✨ this is the screen/device info it's getting applied to.

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🔥 DESCRIPTION 🔥

okay so what does it DO. it sets the colormap cmap for a screen of device info. literally that's it, no cap. you give it a colormap, you give it the device info, it makes the screen's colormap be that colormap. slay. 🫶

and the return value? negative errno on error, or zero on success. so if you get a negative number back, something went wrong (read: it did NOT slay, it gave you an error code instead 😭). if you get zero, you ate. periodt. 💀

ngl, check that return value every time. a negative errno is the kernel's way of saying "girl, no" and you should probably listen.

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🌈 SEE ALSO 🌈

go read these next, bestie, they're all in the kernel file ./drivers/video/fbdev/core/fbcmap.c and they're all lowkey part of the same little colormap friend group 🧚:

• fb_alloc_cmap_gfp(9) — allocation girlie
• fb_dealloc_cmap(9) — the clean-up crew
• fb_copy_cmap(9) — copying queen
• fb_default_cmap(9) — the default vibe
• fb_invert_cmaps(9) — the chaos gremlin, reverses everything

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and that's the whole page!! no notes, she's short and she's perfect ⭐

okay so this was written under ./drivers/video/fbdev/core, dated October 2026, and it's the fb_set_cmap(9) page — so like, shoutout to the kernel docs team for keeping the girlies informed, mwah 💜💅✨