3.7 merge window: conclusion and summary

By Jonathan Corbet
October 17, 2012

Linus pulled a total of 10,409 non-merge changesets into the mainline before closing the merge window for the 3.7 development cycle. That makes 3.7 one of the most active development cycles in recent history; only 3.2, with 10,214 changesets in the merge window, comes close. Clearly, there is a lot going on in the kernel development community.

Interestingly, Linus expressed some skepticism about some of this cycle's work in the 3.7-rc1 announcement. For example, the discussion on the 64-bit ARM patch set concluded some time ago, but Linus came in with a late opinion of his own:

[L]et's see how many years we'll need before the arm people do what every single other 64-bit arch has ever done: merge back with the 32-bit code. As usual, people claimed that there were tons of reasons why *this* time was different, and as usual it's almost certainly going to be BS in the end, and a few years from now we'll have big patches trying to merge it all back. But maybe it really *was* different this time. Snicker.

He also expressed some grumpiness about the user-space API header file split — an enormous set of patches that is only partially merged for 3.7. Header file cleanups, he says, are just too much pain for the benefit that results, so he will not consider any more of them in the future.

Grumbles notwithstanding, he pulled all of this work — and much more — for 3.7. The user-visible changes merged since last week's summary include:

Support for signed kernel modules has been merged. With this feature turned on, the kernel will refuse to load modules that have not been signed with a recognized key. Among other users, full support of UEFI secure boot requires this capability. There is also a mode where unsigned modules will still be loaded, but the kernel will be tainted in the process.
NFS 4.1 support is no longer considered experimental.
The MD RAID layer now supports TRIM ("discard") operations.
New hardware support includes TI LM355x and LM3642 LED controllers, Atmel At91 two-wire interface controllers (replaced driver), and Renesas R-Car I2C controllers.

Changes visible to kernel developers include:

The "UAPI disintegration" patch sets have been pulled into quite a few subsystem trees, causing a lot of header file (and related) churn. A fair amount of this work was deferred to 3.8 as well, though, so this job is not yet done.
The kerneldoc subsystem can now output documents in the HTML5 format.
The kernel now has a generic cooling subsystem based on cpufreq; see Documentation/thermal/cpu-cooling-api.txt for (a few) details.
It's worth noting that some kernel developers have expressed grumpiness about the increase in build time caused by the addition of the signed module feature. Anybody whose work involves doing lots of fast kernel builds will probably want to turn that feature off.

At this point it is time to perform the final stabilization work on all these changes. If things go according to the usual schedule, that should result in the final 3.7 release sometime in early December.

Index entries for this article
Kernel	Releases/3.7