Prominent features of the Linux 4.12 kernel include initial support for AMD Radeon RX Vega graphics cards, intial Nvidia GeForce GTX 1000 "Pascal" accelerated support, implementation of Budget Fair Queueing (BFQ) and storage-I/O schedulers, more MD RAID enhancements, support for Raspberry Pi's Broadcom BCM2835 thermal driver, a lot of F2FS optimizations, as well as ioctl for the GETFSMAP space mapping ioctl for both XFS and EXT4 filesystems.
Linus said in announcing the release that "I think only 4.9 ends up having had more commits," also noting that 4.9 was a Long Term Support kernel, whereas "4.12 is just plain big."
"There's also nothing particularly odd going on in the tree - it's all just normal development, just more of it than usual."
The OCaml team was able pinpoint the issue to Skylake's HyperThreading implementation and notified Intel. While Intel reportedly did not respond directly, it has issued some microcode fixes since then. That's not the end of the story, however, as the microcode fixes need to be implemented into BIOS/UEFI updates as well and it is not clear at this time if all major vendors have included these changes in their latest revisions.
One of RISC-V's inventors co-founded the company, and he says that support is growing -- pointing out that there's already a fork of Linux for RISC-V.