Crate drmkit_dumb 

DRM dumb buffers: GPU-free, CPU-mappable scanout surfaces.

Port of src/dumb/ plus src/buffer_mapping.hpp from drm-cxx @ dc2915b.

Dumb buffers are KMS’s allocation path that needs no accelerator: any driver implementing DRM_CAP_DUMB_BUFFER — every modern KMS driver — can hand back a linear, CPU-mappable pixel buffer. They are the right tool for cursors, client-side decorations, software-rendered UI, and test harnesses.

Invariant 6

Buffer::map is a zero-cost view of a mapping established once and held for the buffer’s whole life. Mapping has no Drop implementation, so “the guard’s destructor is a no-op” is structural rather than documented, and the borrow makes outliving the buffer a compile error.

This is load-bearing beyond convenience: DumbScanoutSink’s pacing depends on map() costing nothing per frame.

Example

use drmkit_core::Device;
use drmkit_dumb::{Buffer, Config, MapAccess};
use drmkit_fmt::fourcc;

let device = Device::open("/dev/dri/card0")?;
let mut buffer = Buffer::create(
    &device,
    &Config { width: 64, height: 64, fourcc: fourcc::XRGB8888, ..Config::default() },
)?;

// Free to acquire, free to drop -- once per frame is fine.
let mut view = buffer.map(MapAccess::Write);
if let Some(row) = view.row_mut(0) {
    row.fill(0xff);
}

Structs

Buffer

An owned dumb buffer, its optional KMS framebuffer, and its CPU mapping.

Config

How a dumb buffer should be allocated.

Mapping

A borrowed view over a dumb buffer’s linear pixel storage.

Enums

DumbError

Errors from dumb-buffer allocation and framebuffer registration.

MapAccess

Intent of a CPU mapping.

Type Aliases

Result

Convenience alias.