A new kernel tree: linux-staging

There's a new kernel tree in town. The linux-staging tree was announced by Greg Kroah-Hartman on 10 June. It is meant to hold drivers and other kernel patches that are working their way toward the mainline, but still have a ways to go. The intention is to collect them all together in one tree to make access and testing easier for interested developers.

According to Kroah-Hartman, linux-staging (or -staging as it will undoubtedly be known) "is an outgrowth of the Linux Driver Project, and the fact that there have been some complaints that there is no place for individual drivers to sit while they get cleaned up and into the proper shape for merging." By collecting the patches in one place, it will increase their visibility in the kernel community, potentially attracting more developers to assist in fixing, reviewing, and testing them.

The intent is for -staging to house self-contained patches—Kroah-Hartman mentions drivers and filesystems—that should not affect anyone who is not using them. Because of that, he is hoping that -staging can get included in the linux-next tree. As he says to Stephen Rothwell, maintainer of -next, in the announcement:

The -next tree is meant for things that are headed for inclusion in the "N+1" kernel (where 2.6.N is the release under development), so including code not meant for that release is bending the rules a bit. As of this writing, Rothwell has not responded to the request to include -staging, but it would clearly benefit those patches to have a wider audience—with only a small impact on -next. There is no set timeline for patches to move from -staging into mainline, Kroah-Hartman says:

The -staging tree is seen as a great place for Kernel Janitors and others who are interested in learning about kernel development to get their start. The announcement notes: "The code in this tree is in desperate need of cleanups and fixes that can be trivially found using 'sparse' and 'scripts/checkpatch.pl'." In the process of cleaning up the code, folks can learn how to create patches and how to get them accepted into a tree. From there, the hope is that more difficult tasks will be undertaken—with -staging or other kernel code—leading to a new crop of kernel hackers.

The current status of -staging shows 17 patches, most of which are drivers from the Linux Driver Project. Kroah-Hartman is actively encouraging more code to be submitted for -staging, as long as it meets some criteria for the tree. The tree is not meant to be a dumping ground for drivers that are being "thrown over the wall" in hopes that someone else will deal with them. It is also not meant for code that is being actively worked on by a group of developers in another tree somewhere—the reiser4 filesystem is mentioned as an example—it is for code that would otherwise languish.

The reaction on linux-kernel has so far been favorable, with questions being asked about what kinds of patches are appropriate for the tree, in particular new architectures. The -staging tree fills a niche that has not yet been covered by other trees. It also serves multiple purposes, from giving new developers a starting point to providing additional reviewing and testing opportunities for new drivers and other code. With luck, that will hasten the arrival of new features—along with new developers.

Actually, why not include these immature drivers, as long as they are marked using the "Code
maturity" stuff as "scary immature"?  They're more likely to get widespread review and
development help if others can actually see them.

Because 'scary immature' stuff never gets remarked as 'OK'. (See 
EXPERIMENTAL, OBSOLETE et al).