On Sat, Jan 9, 2021 at 10:03 AM Kyle Evans <kev...@freebsd.org> wrote:
> On Fri, 8 Jan 2021 at 19:43, Warner Losh <i...@bsdimp.com> wrote: > > > > The FreeBSD project has rewritten bsd-user. We've been working on this > for quite some time (the earliest commits date from 2013). Maybe a dozen > people have worked on this over time, and there's 3 or 4 active developers > focused on FreeBSD changes at the moment. > > > > For a while, we'd merge in upstream changes from qemu. This worked great > for us, but left us with a big backlog that was hard to upstream. Each of > the updates took some time, so we got a little behind. > > > > So, a few years ago, I spent several weeks converting the tangled merge > mess into a set of linear patches and started moving that forward. This was > around the time 4.0 was released. I only managed to get the rebase forward > to 3.1 release at the time before I hit problems related to poor testing > environment making it hard to verify newer versions were still working. > Plus, we found a few bugs that took a while to resolve for a number of > reasons. Now that they are resolved, we're able to use qemu-bsd-user to > build ~30k packages for arm, and ~20k for different types of mips in > FreeBSD "ports" system. We now have great confidence that it's working well > again. > > > > Now that those bugs are resolved, I started trying to forward-port the > two-year-old base and immediately found myself hitting a number of > problems. A big problem was that I was re-doing a lot of work that was due > to innoculous changes upstream that I wouldn't have to do if the bsd-user > changes were upstream. These changes get in the way of dealing with the > more substantial structural changes in qemu that have happened. > > > > There had been talk of doing a remove and replace update of bsd-user. > This talk was before I managed to rebase things as far forward as 3.1 even. > This appealed to me because we've accumulated about 150 patches to date, > many quite large, and curating them into a set of maybe 400 or 500 changes > to match the size and scope of most patches I've seen posted to qemu-devel > seemed overwhelming. > > > > However, it's been another year since that plan was hatched, and it's > become clear to me that plan won't end in success. The closest I've been > able to get is 3.1 when 4.1 was current (about 6 months behind). It's time > for a new plan. > > > > As one of the developers on the FreeBSD side, I agree with this. In > addition to the reasons cited, reintroducing it would really take a > lot more time and effort and I'm not convinced it would ever be > completed because, IMO, going that route should really entail > redesigning it from the ground-up based on an abstraction of > linux-user. I find that right now I'm playing a lot of catch-up > because we seem to be largely copied from linux-user without later > improvement; there is a really healthy amount of platform-independent > stuff that really should end up ultimately shared in a qemu-user or > something to that effect to mitigate duplication of effort. > Yes. Once we have things upstream the normal 'refactoring' work can be done there, rather than in a side repo where it will quickly go stale. Also, once it's in upstream, then the NetBSD and OpenBSD folks can come back to the table with a much smaller delta to get things working again than they have today. > > So, my new plan is to rebase what changes I can to the tip of master and > submit those for review. I'll work with the developers on the FreeBSD side > to ensure they are included in reviews in addition to the normal qemu-devel > list. This will allow us to pare down the deltas between our code and > upstream to allow us to make progress. The changes will be held to the > standard 'makes things better'. Given how broken bsd-user is today in qemu > upstream, at first that will a very easy standard to make. > > > > The first patch I'll submit will be changing MAINTAINERS to point to me, > since I'm acting as the point person in this effort. I'll then re-submit > some other changes that I've submitted in the past, but CC the FreeBSD > folks that are currently active (they were only CC'd to former developers > who lack the time to review). > > > > Thanks for taking this on! > You bet. Warner
