With Linux 4.5-rc1 expected for release today that will mark the end of this cycle's merge window, here is a look at the new features and improved functionality present for this major Linux kernel release that will then be officially christened in about two months time.
The Linux 4.5 merge window was yet another exciting two week period with many new features landing for all users of this open-source kernel. The highlights for my intense monitoring of the Linux kernel Git code and mailing list over the past two weeks are listed ahead.
- The Etnaviv DRM driver was added as open-source, reverse-engineered support for Vivante's GPU IP cores as common to ARM SoCs and elsewhere.
- Initial i915 DRM graphics support for next-gen Kabylake hardware. The Skylake successor will be out later this year and with Linux 4.5 comes the initial support. There is also a variety of other fixes and improvements to the Intel DRM driver.
- The Radeon DRM driver finally drops user-space mode-setting support. It hasn't really been used in years thanks to kernel mode-setting (KMS) being far superior and the choice done by all major drivers these days compared to UMS.
- The new AMDGPU driver has PowerPlay support for being able to re-clock the latest Tonga/Fiji discrete graphics cards. Sadly, this PowerPlay support in AMDGPU is disabled by default: a Kconfig option must be enabled and there is also a kernel module parameter that must also be set for enabling this much needed feature.
- AMDGPU and Radeon also have some optimizations and other improvements for bettering the open-source AMD Linux graphics stack.
- PCI Express link speed change support and other Nouveau driver improvements for this open-source NVIDIA code. Sadly, there's still no GeForce GTX 900 series support pending NVIDIA putting out the signed firmware images. The Kepler/Fermi re-clocking state also still leaves a lot to be desired for allowing good open-source driver performance.
- While the VC4 DRM driver was previously added as the Raspberry Pi kernel mode-setting driver, the kernels up to now haven't had the necessary bits for supporting 3D/OpenGL in conjunction with the new VC4 Gallium3D driver from Mesa. However, with Linux 4.5 those needed kernel bits are in place for having a fully open Raspberry Pi 3D driver stack.
- Various DRM core improvements, atomic mode-setting support for some of the smaller DRM drivers, runtime power management for the Exynos DRM driver, and other changes.