Linux 5.10

Linus Torvalds has tagged Linux 5.10, which will be the next long term support release. Despite a relatively small merge window, it includes nearly 14,000 commits.

Big new features in 5.10 include an ext4 performance improvement by reducing the amount of journal metadata written for crash recovery (unfortunately this feature right now needs to be enabled at the time the volume is mkfsed), secure ring sharing for io_uring, an API for manager processes to supply memory hints to other processes (I'm sure that won't be abused by anyone), support for static calls with in-place code patching as a better post-Spectre function pointer replacement than retpolines, widened timestamps on xfs to handle Y2038 (this wasn't already a thing? but requires explicit transitioning of old filesystems), lots of BPF improvements and many new drivers.

On the Power ISA specific side, 5.10 adds further support for POWER10 (shallow stop states and new watchpoint features), a fix for the three of you using a POWER9 in HPT mode with 4K pages and more than 16TB of RAM (or RAM attached to a second node), a filter for RTAS firmware calls to protect kernel memory, and better topology-aware scheduling on POWER9 and POWER10.

The saddest thing announced in this kernel, however, is the end of support for the original PowerPC 601. This is understandable as the 601 was always intended as a stepping-stone CPU and had important differences from classic PowerPC as later implemented in the 603, which had to be accounted for in system software. Nevertheless, if you've still got a Power Mac 6100 in your closet running Linux, your last call in LTS kernels is 5.8 (or 5.9, if you need the features).