What is it all about?
libdrm is a low-level userspace library which supply DRM access and support the ioctl interface. it's a library which generally used by graphics device drivers such as Mesa DRI, X drivers, libvaand other similar projects.
* Provides wrapper functions for the ioctls to avoid exposing the kernel interface directly, and for chipsets with drm memory manager. * Support for tracking relocations and buffers. * Used by graphics drivers such as the Mesa DRI drivers, the X drivers, libva and similar projects.