The highlights to the Linux 3.9 kernel that Linus points out in his -rc1 announcement is the new Metag and ARC CPU architecture ports, lots of ARM work, MIPS doing some clean-ups, EXT4/Btrfs file-system improvements, and the usual scenario where the bulk of the changes are within the Linux drivers.
Last week I wrote about my Top Features of the Linux 3.9 kernel. Over the past two weeks there's also been tons of Phoronix articles covering the other interesting changes to this next big Linux kernel update.
Embedded below is Torvalds' 3.9-rc1 announcement in full:
It's been two weeks (ok, thirteen days, but close enough), and the merge window is closed, and I've cut the 3.9-rc1 release.
I don't know if it's just me, but this merge window had more "Uhhuh" moments than I'm used to. I stopped merging a couple of times, because we had bugs that looked really scary, but thankfully each time people were on them like paparazzi on Justin Bieber. Special thanks to Peter, Ted and Rafael (and the people who reported the bugs too!) for being so responsive. It could have been so much worse.
As usual, there's changes all over the place. We've got two new architectures (metag and arc), and we've got tons of arm work (as usual), with even more platforms falling under the generic umbrella. MIPS tried to keep up by doing whitespace cleanup, but those arm people with their platform changes kept ahead
And we've got filesystem updates to just about everything out there, although btrfs (initial raid56 code, snapshot work and fsync performance) and ext4 (hole punching, extent caches, also fsync performance) had the big changes.
But most of the updates (~60%) are on the driver side, as usual. The bulk is in GPU, networking, staging, pinctrl, sound, but it's all over.
There is a lot of stuff there, and as usual even the shortlog is really too big to pst or read through. I'd suggest using git to check whatever particular area you're interested in..