Analysis of information sources in references of the Wikipedia article "Direct Rendering Manager" in English language version.
GEM essentially deals with graphics buffer objects (which can contain textures, renderbuffers, shaders, or all kinds of other state objects and data used by the gpu)
Historically, the X server was responsible for saving output state when it started up, and then restoring it when it switched back to text mode. Fast user switching was accomplished with a VT switch, so switching away from the first user's X server would blink once to go to text mode, then immediately blink again to go to the second user's session.
right now there's 17 drivers supporting atomic modesetting merged into the DRM subsystem
DRM/KMS driver fully working now, although still without DMA. Oh, and it's written in Rust, although it's mostly just full of raw unsafe blocks.
Cool thing is, since we have a 'normal' DRM/KMS driver (and help from @emersion@hackerspace.pl) we can just do things like... run Wayland! Weston on an iPod Nano 5G.
uses an onboard display chip that is integrated into the management chip Hi1710 and uses the IP core of the SM750
GEM flink has lots of issues. The flink names are global, allowing anyone with access to the device to access the flink data contents.
A more subtle limitation is that the driver couldn't handle interrupts, so there wasn't any hot-plug monitor support.
Graphics cards are programmed in numerous ways, but most initialization and mode setting is done via memory-mapped IO. This is just a set of registers accessible to the CPU via its standard memory address space. The registers in this address space are split up into ranges dealing with various features of the graphics card such as mode setup, output control, or clock configuration.
I believe the best solution to this problem is for the kernel to provide a single, comprehensive device driver for each piece of video hardware. This means that conflicting drivers like fbdev and DRM must be merged into a cooperating system. It also means that poking hardware from user space while a kernel based device driver is loaded should be prevented.
Many modern high-end GPUs come with their own memory managers. They even include several different caches that need to be synchronized during access. [...] . Therefore, memory management on GPUs is highly driver- and hardware-dependent.
uses an onboard display chip that is integrated into the management chip Hi1710 and uses the IP core of the SM750
gem-flink doesn't provide any private namespaces to applications and servers. Instead, only one global namespace is provided per DRM node. Malicious authenticated applications can attack other clients via brute-force "name-guessing" of gem buffers
