Intel's Iris Gallium3D driver for modern OpenGL support works on hardware going back to old Broadwell processors with "Gen8" integrated graphics as does the HasVK Vulkan driver for Haswell/Broadwell. But in allowing to focus on the common Skylake "Gen9" graphics and newer/future Intel graphics architectures, pending Mesa code is working to split-off that old Broadwell/Gen8 code. The Gen8 support will continue to be in-tree but separated from the rest of the compiler code so that the code can continue to be improved for newer Intel hardware without risking regressions/breaking those still on Broadwell era processors...