Re: qemu bsd-user plans

[Warner Losh <imp@bsdimp.com>]

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On Mon, Jan 11, 2021 at 6:27 AM Daniel P. Berrangé <berrange@redhat.com>
wrote:

> On Fri, Jan 08, 2021 at 12:41:30PM -0700, Warner Losh 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.
>
> The fact that you have 3-4 people involved in this work is will be very
> helpful to you going forward with a QEMU maintenance.
>
> The biggest problem with getting code merged into QEMU is an insufficient
> number of reviewers for the amount of patches sent. Since we have a rule
> that patches need a review from someone else who isn't the author, if there
> are two people with expertize to review patches in a given QEMU subsystem,
> then they can become self-sufficient and review each others patches on
> qemu-devel, which then makes merging much more productive.
>

Yes. That's my hope too. We've been doing this internally for changes we've
been landing lately, so I think expanding our process to also do this with
qemu upstream will be a natural progression...


> If anyone wants to be automatically CC'd on patches for bsd-user for the
> purposes of acting as a designated reviewer, they can added to MAINTAINERS
> file to, alongside the primary maintainer(s).
>

I'll be adding myself, at least, to MAINTAINERS and encouraging the others
that have been working on this to take the time to review when I post. They
are quite willing, but may lack the time, alas, so I'll do what I can to
time the patches such that at least one of them has the time in a
reasonable time frame...


> > 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).
>
> > But before I get too far down this path, I thought I'd send out what's
> > going on to qemu-devel so I can get feedback and adjust the plan into
> > something that's mutually agreeable so time I put towards this is not
> > wasted.
>
> No objections from me. Since current bsd-user is orphaned, largely
> unusable, and you're volunteering your time to make it better, I'm
> supportive of whatever you believe is the most time efficient way
> to improve bsd-user.
>
> I presume some of the current QEMU maintainers knowledgable about
> linux-user will be able to review the patches, and as mentioned
> above, if other BSD devs currently active in bsd-user work can
> also provide reviews on qemu-devel that'll be useful long term.
>

Yes. Many of the patches are copied from there, as well as the initial
version coming largely from there as well (it seems, I wasn't around at the
time and base this entirely on code similarities).

The FreeBSD project makes such heavy use of this, that I really want to
find some way we can stay current and maybe even have better abstractions
that make all user-mode emulation easier...

Warner

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