Kernel mode setting
| Original author(s) | kernel.org & freedesktop.org |
|---|---|
| Developer(s) | kernel.org & freedesktop.org |
| Written in | C |
| Type | |
| License | |
| Website |
In computing, the Direct Rendering Manager (DRM), a subsystem of the Linux kernel, interfaces with the GPUs of modern video cards. DRM exposes an API that user-space programs can use to send commands and data to the GPU, and to perform operations such as configuring the mode setting of the display. DRM was first developed as the kernel space component of the X Server's Direct Rendering Infrastructure, but since then it has been used by other graphic stack alternatives such as .
User-space programs can use the DRM API to command the GPU to do hardware-accelerated 3D rendering and video decoding as well as GPGPU computing.
The Linux Kernel already had an API called fbdev allowing to manage the framebuffer of a graphics adapter, but it couldn't be used to handle the needs of modern 3D accelerated GPU based video cards. These type of cards usually require setting and managing a command queue in the card's memory (Video RAM) to dispatch commands to the GPU, and also they need a proper management of the buffers and free space of the Video RAM itself. Initially user space programs (such as the X Server) directly managed these resources, but these programs usually acted as if they were the only ones with access to the card's resources. When two or more programs tried to control the same video card at the same time, and set its resources each one in its own way, most times they ended catastrophically.
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Wikipedia