"This is a request to merge KGDB into the mainline kernel," Jason Wessel announced, posting a series of patches aiming toward that goal. He continued, "as of right now KGDB is comprised of 21 different patches adding in the core api and docs first and then working up to add drivers and arch specific support to KGDB. The patches were broken down into logical pieces for review and comments." He went on to explain:
"The intent of the KGDB patches is to unify the KGDB support across all the architectures that elect to implement the KGDB functionality by providing a common core and an arch specific stub. For quite some time there has been different features and uses of KGDB across the most popular architectures. Having a common core that takes care of protocol parsing and the typical use case of software breakpoints should eliminate the inconsistencies across the archs as well as making it easier to add KGDB support to a new arch."
Andrew Morton, who has been supportive of getting a kernel debugger into the mainline kernel, explained that it was too late in the 2.6.24 review cycle to merge KGDB, meaning it would have to wait for 2.6.25 at the earliest, "this won't work very well. There's a lot of review work to be done here, and a lot of it by busy architecture maintainers. Expecting people to do all this review and test work late in the merge window when they're all madly scrambling to get their bugs^Wpatches into mainline is not reasonable. This should all have started a month ago. So we're looking at a 2.6.25 merge for this work."
"Is anyone testing the kgdb code in here?" Andrew Morton asked in his release announcement for the 2.6.23-rc1-mm2 patchset. Mike Frysinger asked, "does kgdb actually have a chance to get merged? With the history of it, i just assumed it was never going in". In the past, Linus Torvalds has resisted merging kernel debuggers and famously said, "I don't like debuggers. Never have, probably never will," going on to explain why he didn't want it to be too easy to hack the Linux kernel. An earlier push to get kgdb merged in 2004 didn't succeed, though some architectures already have versions of the debugger. The current kgdb patchset in Andrew's tree includes code for the i386, x86_64, ppc, mips, sh and arm architectures.
Andrew replied to Mike's question, "I was hoping for a 2.6.24 merge. But I haven't actually looked at it yet. Hopefully Jason is planning to get it all out for review soonish." He went on to add, "runtime testing isn't actually the most important thing at this time - if is doesn't work, well hey, we fix it, easy - we always have bugs. The main emphasis right now should be on higher-level design/review/integration stuff." Jason Wessel noted, "the KGDB tree is broken up into incremental units each layer adding more functionality and or arch specific pieces."