While your x86 and AMD64 computer will usually boot with Linux mainline without issues, most ARM boards and device won’t, and many of the ones that do boot only support headless mode, and limited functionalities. The Raspberry Pi had been supporting HDMI output with a simple framebuffer for a while, but a developer working on the Videocore 4 (VC4) GPU found inside Broadcom BCM2835 and BCM2836 processors, has recently submitted a patchset to add VC4 GPU to Linux mainline that should make it to Linux 4.4.
The commit message does mention some features are still missing, but it’s a start:
This pull request introduces the vc4 driver, for kernel modesetting on the Raspberry Pi (bcm2835/bcm2836 architectures). It currently supports a display plane and cursor on the HDMI output. The driver doesn’t do 3D, power management, or overlay planes yet.
Via Golem and Sanders.