It was recently pointed out that the stock 2.6.2 kernel contains in-kernel support for kgdb for some architectures, but not i386. 2.6 maintainer Andrew Morton replied, "lots of architectures have had in-kernel kgdb support for a long time. Just none of the three which I use :(" As to getting kgdb for i386 into the kernel, he explained some reluctance:
"I wouldn't support inclusion of i386 kgdb until it has had a lot of cleanup, possible de-featuritisification and some thought has been applied to splitting it into arch and generic bits. It's quite a lot of work."
It was quickly pointed out that Amit Kale has done much of this work with his version of kgdb, available here. Andrew replied, "Look, there's a lot of interest in this and I of course am fully supportive. If someone could send me Amit's patchset when they think I should test it, I could then talk about it more usefully." Read on for much of the lkml thread, including specifics reasons why and why not to include kgdb in the stock 2.6 kernel.
Andrew Morton [interview] has released 2.6.2-rc3-mm1, including a new debug patch to detect when a process calls i_size_write() without holding the inode's i_sem. Andrew explains, "It generates a warning and a stack backtrace. We know that XFS generates such a trace. It will turn itself off after the first ten warnings. Please don't report the XFS case." Also appearing in this kernel is Rusty Russell's CPU hotplug code, recently discussed on the lkml. It is pointed out that 2.6.2-rc3-mm1 is broken on the ppc64 architecture, "something to do with the sched-domains patch although at this stage we do not know whether the problem lies with that patch or with the ppc64 code."
The desire to merge reiser4 [story] into the -mm kernel was again raised. Andrew responded favorably enough, requesting the necessary patches and complete documentation. He does caution, "be aware that the barriers for a new filesystem are relatively high: each one adds a significant maintenance burden to the VFS and MM developers. It will need cautious review." This comment is evidently in reference to 2.6 inclusion, not -mm inclusion, as he goes on to add, "but that doesn't mean we cannot get it out there, get you some more testing and exposure."