Re: [Qemu-devel] [PATCH for-3.2 00/41] RFC: slirp: make it again a standalone project

[Dr. David Alan Gilbert]

* Markus Armbruster (address@hidden) wrote:
> Thomas Huth <address@hidden> writes:
> 
> > On 2018-11-14 13:59, Markus Armbruster wrote:
> >> Marc-André Lureau <address@hidden> writes:
> >> 
> >>> Hi,
> >>>
> >>> Based-on: https://people.debian.org/~sthibault/qemu.git/ slirp branch
> >>>
> >>> This series goal is to allow building libslirp as an independent library.
> >>>
> >>> While looking at making SLIRP a seperate running process, I thought
> >>> that having an independent library from QEMU would be a first step.
> >>>
> >>> There has been some attempts to make slirp a seperate project in the past.
> >>> (https://lists.gnu.org/archive/html/qemu-devel/2017-02/msg01092.html)
> >>> Unfortunately, they forked from QEMU and didn't provide enough
> >>> compatibility for QEMU to make use of it (in particular, vmstate
> >>> handling was removed, they lost git history etc). Furthermore, they
> >>> are not maintained as far as I can see.
> >>>
> >>> I would propose to make slirp a seperate project, that can initially
> >>> be used by QEMU as a submodule, keeping Makefile.objs until a proper
> >>> shared library with stability guarantees etc is ready..
> >>>
> >>> The subproject could created by preserving git tags, and cleaning up the 
> >>> code style, this way:
> >>>
> >>> git filter-branch --tree-filter "if ls * 1> /dev/null 2>&1; then 
> >>> clang-format -i * /dev/null; fi " -f --subdirectory-filter "slirp" 
> >>> --prune-empty --tag-name-filter cat -- --all
> >>> (my clang-format 
> >>> https://gist.github.com/elmarco/cb20c8d92007df0e2fb8a2404678ac73)
> >>>
> >>> What do you think?
> >> 
> >> Has the slirp code been improved to be generally useful?  I still got it
> >> filed under "friends don't let friends use that, except for testing"...
> >
> > The slirp code is already used in a lot of other projects:
> 
> The issue I have with SLIRP isn't that it solves a useless problem (au
> contraire!), it's that it's a useless solution.  Okay, that's an unfair
> exaggeration, it's not useless, I just wouldn't trust it in production,
> unless it has improved significantly since I last looked at it.

It's now used as a critical part of 'rootless-containers' - i.e. running
containers with no priviledges; see:
https://github.com/rootless-containers/slirp4netns/

Dave

> > - WinUAE
> >   (https://github.com/tonioni/WinUAE/tree/master/slirp)
> >
> > - Previous
> >   (https://sourceforge.net/p/previous/code/HEAD/tree/trunk/src/slirp/)
> >
> > - BasiliskII
> >   (https://github.com/cebix/macemu/tree/master/BasiliskII/src/slirp)
> >
> > - Bochs
> >
> > (https://sourceforge.net/p/bochs/code/HEAD/tree/trunk/bochs/iodev/network/slirp/)
> >
> > ... and likely many more. AFAIK they all (or at least most) have been
> > forked from the QEMU code at one point in time and diverged, i.e. they
> > likely missed the bug fixes and new features that have been added in
> > QEMU (like IPv6). So yes, IMHO it makes a lot of sense to try to make a
> > separate library out of the slirp code again, especially if we could
> > convince the other projects to use it, too, and to collaborate on that
> > version.
> 
> No objections to spinning it out, as long as it comes with a fair
> assessment of its limitations.
> 
> Turning it into a proper project might even improve its chances to
> get improved towards production quality, compared to its current
> existence as a corner of QEMU next to nobody wants to touch.
> 
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK