Jeff Merkey is hoping to see his MDB Linux Kernel Debugger added to Linux 4.6. This MDB Merkey's Kernel Debugger is a complete rewrite of the earlier version of his debugger, which dates back to the Linux 2.2 kernel days. x86 and x86_64 are currently supported. Those wanting to check out the new code can find it via this commit.
Merkey has long been offering the MDB debugger as a standalone component via this GitHub page while now for Linux 4.6 he's hoping to see it merged as a mainline, in-tree debugger. This debugger would add 23,000+ lines of new code to the kernel.
Linus Torvalds in the past didn't want a debugger in the kernel tree in the past but with KDB/KGDB being around, we'll see soon enough what he's thinking about MDB for Linux 4.6. The pull request is here.