STRUCT DRM_FB_HELPER_SURFACE_SIZE(9)

💅 struct drm_fb_helper_surface_size — NAME ✨

okay so bestie, <purple>struct drm_fb_helper_surface_size</purple> is literally the struct that describes fbdev size and scanout surface size. that's the whole vibe. this is from the Kernel API Manual, and we're gonna get into it 🎀

---

🦋 SYNOPSIS 🦋

struct drm_fb_helper_surface_size {
    u32 fb_width;
    u32 fb_height;
    u32 surface_width;
    u32 surface_height;
    u32 surface_bpp;
    u32 surface_depth;
 };

no cap, that's the whole shape of it. let's meet the members 💖

🌸 Members 🌸

• fb_width — the fbdev width, bestie. that's it, that's the field 🫶
• fb_height — the fbdev height. iconic. ✨
• surface_width — the width of the scanout buffer 👑
• surface_height — the height of the scanout buffer 👑
• surface_bpp — the bpp of the scanout buffer, yes literally 🍓
• surface_depth — the depth of the scanout buffer 🌈

---

⭐ Description ⭐

okay so here's the part you actually need to know, and it's giving important 💀

note that the scanout surface width/height may be larger than the fbdev width/height. not a typo, not a bug, that's just how it is.

in the case of multiple displays, the scanout surface gets sized according to the largest width/height — so it's large enough for all the CRTCs to scanout. slay, everything fits 💅

but the fbdev width/height? that gets sized to the minimum width/height of all the displays. why? because this ensures that fbcon fits on the smallest of the attached displays 🧚 so the tiny monitor doesn't get left out, periodt.

also like, fb_width/fb_height is used by drm_fb_helper_fill_info to fill out the fb_info.var structure. iykyk 🔥

---

🎀 SEE ALSO 🎀

• Kernel file ./include/drm/drm_fb_helper.h
• struct drm_fb_helper_funcs(9)
• struct drm_fb_helper(9)
• DRM_FB_HELPER_DEFAULT_OPS(9)

---

and that's the tea, bestie 🍓 this whole thing lives in ./include/drm, from the October 2026 era of the Kernel API Manual, filed under struct drm_...surface_size(9) — mwah, go read the other ones too 💜🦋