STRUCT VFIO_REGION_GFX_EDID(9)

📦 version 7.3.1, in nixpkgs unstable

💅 struct vfio_region_gfx_edid(9) — the kernel API manual, bestie edition 🎀

okay so real talk, this is a page from the Kernel API Manual and honestly? it's giving "niche but iconic." it's all about struct vfio_region_gfx_edid and baby, we are about to understand it fr fr. ✨

🌸 NAME 🌸

struct vfio_region_gfx_edid — literally just the EDID region layout. that's the whole vibe. 💖

🦋 SYNOPSIS 🦋

here's the whole struct, copied exactly because we do NOT play with code integrity:

struct vfio_region_gfx_edid {
    __u32 edid_offset;
    __u32 edid_max_size;
    __u32 edid_size;
    __u32 max_xres;
    __u32 max_yres;
    __u32 link_state;
  #define VFIO_DEVICE_GFX_LINK_STATE_UP    1;
  #define VFIO_DEVICE_GFX_LINK_STATE_DOWN  2;
 };

look at her. six __u32 fields and two #defines. main character energy, no cap. 👑

✨ Members ✨

okay so each of these is a member of the struct, and the little parenthetical tells you whether you can write to it or not. pay attention, this matters:

  • edid_offset — where the edid blob lives, relative to the start of the region. it's readonly, so look but don't touch. 🙈
  • edid_max_size — the max size of the edid blob. also readonly. it's giving "boundaries." 🫶
  • edid_size — the actual edid size. this one is read/write, so you CAN change it, slay. 💅
  • max_xres — max display width. 0 means no limitation. readonly. 🎀
  • max_yres — max display height. 0 means no limitation. readonly. 🎀
  • link_state — display link state, read/write. two possible vibes:
    • VFIO_DEVICE_GFX_LINK_STATE_UP — monitor is turned on 🟢
    • VFIO_DEVICE_GFX_LINK_STATE_DOWN — monitor is turned off 🔴

🌈 Description 🌈

so what does this thing actually do? it sets the display link state and the EDID blob. that's the job. ⭐

and what even IS an EDID blob? bestie, it's monitor information — brand, name, serial number, physical size, supported video modes and more. basically the monitor's whole little ID card. 🪪✨

this special region lets userspace (typically qemu, iykyk) set a virtual EDID for the virtual monitor, which means you get a flexible display configuration. obsessed. 😭💖

if you wanna read the actual edid blob spec, look here:

https://en.wikipedia.org/wiki/Extended_Display_Identification_Data

and on linux systems you can find the EDID blob chillin' in sysfs:

/sys/class/drm/${card}/${connector}/edid

also!! you can use the edid-decode ulility (yes, that's how the original spells it, we keep it exact 🫶) which comes with xorg-x11-utils to decode the EDID blob. decoding era. 🧚

⚠️ here's the EDID update protocol, and bestie you gotta do it in this order or it's not gonna slay: 1. set link-state to down 🔴 2. update edid blob and size ✍️ 3. set link-state to up 🟢 that's the whole ritual. in order. periodt. 💀

👑 SEE ALSO 👑

kernel file ./include/uapi/linux/vfio.h, plus these icons:

and that's the whole page, bestie, you ate that 🍓

cute little sign-off: this one came from ./include/uapi/linux, dated October 2026, and it's the struct vfio_region_gfx_edid(9) page. mwah. 💜✨

📦 where this page comes from