On Thu, Dec 06, 2018 at 12:32:47PM +0000, Kieran Bingham wrote: > Oh - although, yes - there are some good concepts there - but I'm a bit > weary of how easy it would be to 'run' the said test against multiple > kernel version libraries... there would be a lot of possible ABI > conflicts perhaps. > > My main initial idea for a libumlinux is to provide infrastructure such > as our linked-lists and other kernel formatting so that we can take > kernel code directly to userspace for test and debug (assuming that > there are no hardware dependencies or things that we can't mock out) I think this would be a really wonderful to make happen, and could potentially be much wore widely useful than for just running tests, by making it easier to share code between both kernel and userspace. For bcachefs I've got a shim layer that lets me build almost everything in fs/bcachefs and use it as a library in the userspace bcachefs-tools - e.g. for fsck and migrate. Mine was a quick and dirty hack, but even so it's been _extremely_ useful and a major success - I think if this became something more official a lot of uses would be found for it. I'm not sure if you've actually started on this (haven't seen most of the thread yet), but if any of the bcachefs-tools shim code is useful feel free to steal it - I've got dirt-simple, minimum viable shims for the kthread api, workqueus, timers, the block layer, and assorted other stuff: https://evilpiepirate.org/git/bcachefs-tools.git/ Going forward, one issue is going to be that a libumllinux is going to want to shim some interfaces, and for other things it'll just want to pull in the kernel implementation - e.g. rhashtables. It might be nice if we could refactor things a bit so that things like rhashtables could be built as a standalone library, as is.
