> -----Original Message----- > From: Thomas Huth <th...@redhat.com> > Sent: Monday, June 20, 2022 5:44 PM > To: Zhang, Chen <chen.zh...@intel.com>; Daniel P. Berrangé > <berra...@redhat.com> > Cc: Jason Wang <jasow...@redhat.com>; qemu-dev <qemu- > de...@nongnu.org>; Paolo Bonzini <pbonz...@redhat.com>; Eduardo > Habkost <edua...@habkost.net>; Eric Blake <ebl...@redhat.com>; Markus > Armbruster <arm...@redhat.com>; Peter Maydell > <peter.mayd...@linaro.org>; Laurent Vivier <lviv...@redhat.com>; Yuri > Benditovich <yuri.benditov...@daynix.com>; Andrew Melnychenko > <and...@daynix.com> > Subject: Re: [RFC PATCH 01/12] configure: Add iovisor/ubpf project as a > submodule for QEMU > > On 20/06/2022 11.29, Zhang, Chen wrote: > > > > > >> -----Original Message----- > >> From: Thomas Huth <th...@redhat.com> > >> Sent: Monday, June 20, 2022 4:47 PM > >> To: Daniel P. Berrangé <berra...@redhat.com>; Zhang, Chen > >> <chen.zh...@intel.com> > >> Cc: Jason Wang <jasow...@redhat.com>; qemu-dev <qemu- > >> de...@nongnu.org>; Paolo Bonzini <pbonz...@redhat.com>; Eduardo > >> Habkost <edua...@habkost.net>; Eric Blake <ebl...@redhat.com>; > Markus > >> Armbruster <arm...@redhat.com>; Peter Maydell > >> <peter.mayd...@linaro.org>; Laurent Vivier <lviv...@redhat.com>; Yuri > >> Benditovich <yuri.benditov...@daynix.com>; Andrew Melnychenko > >> <and...@daynix.com> > >> Subject: Re: [RFC PATCH 01/12] configure: Add iovisor/ubpf project as > >> a submodule for QEMU > >> > >> On 20/06/2022 10.11, Daniel P. Berrangé wrote: > >>> On Mon, Jun 20, 2022 at 05:59:06AM +0000, Zhang, Chen wrote: > >>>> > >>>> > >>>>> -----Original Message----- > >>>>> From: Daniel P. Berrangé <berra...@redhat.com> > >>>>> Sent: Friday, June 17, 2022 4:05 PM > >>>>> To: Zhang, Chen <chen.zh...@intel.com> > >>>>> Cc: Jason Wang <jasow...@redhat.com>; qemu-dev <qemu- > >>>>> de...@nongnu.org>; Paolo Bonzini <pbonz...@redhat.com>; Eduardo > >>>>> Habkost <edua...@habkost.net>; Eric Blake <ebl...@redhat.com>; > >>>>> Markus Armbruster <arm...@redhat.com>; Peter Maydell > >>>>> <peter.mayd...@linaro.org>; Thomas Huth <th...@redhat.com>; > >> Laurent > >>>>> Vivier <lviv...@redhat.com>; Yuri Benditovich > >>>>> <yuri.benditov...@daynix.com>; Andrew Melnychenko > >>>>> <and...@daynix.com> > >>>>> Subject: Re: [RFC PATCH 01/12] configure: Add iovisor/ubpf project > >>>>> as a submodule for QEMU > >>>>> > >>>>> On Fri, Jun 17, 2022 at 03:36:19PM +0800, Zhang Chen wrote: > >>>>>> Make iovisor/ubpf project be a git submodule for QEMU. > >>>>>> It will auto clone ubpf project when configure QEMU. > >>>>> > >>>>> I don't think we need todo this. As it is brand new functionality > >>>>> we don't have any back compat issues. We should just expect the > >>>>> distros to ship ubpf if they want their QEMU builds to take advantage > of it. > >>>>> > >>>> > >>>> Yes, agree. It's the best way to use the uBPF project. > >>>> But current status is distros(ubuntu, RHEL...) does not ship the > >>>> iovisor/ubpf like the iovisor/bcc. So I have to do it. > >>>> Or do you have any better suggestions? > >>> > >>> If distros want to support the functionality, they can add packages > >>> for it IMHO. > >> > >> Yes, let's please avoid new submodules. Submodules can sometimes be a > >> real PITA (e.g. if you forget to update before rsync'ing your code to > >> a machine that has limited internet access), and if users install > >> QEMU from sources, they can also install ubpf from sources, too. > >> And if distros want to support this feature, they can package ubpf on > >> their own, as Daniel said. > > > > Hi Daniel and Thomas, > > > > I don't know much the background history of QEMU submodules, but > meson > > build is a submodule for QEMU too. It means user can't install QEMU > > from sources with limited internet access. > > There is no written policy, but I think the general consensus is that we only > ship code in submodules if: > > 1) It's not available in a required version in distros yet > > and > > 2) it is essentially required to build QEMU (like meson) or if the feature has > been part of the QEMU sources before and then moved to a separate > repository (like slirp). > > We ship meson as a submodule since we require some meson features that > are not available with the meson versions in the distros yet. Once the distros > catch up, we'll likely remove the meson submodule from QEMU. > > > And back to Daniel's comments, Yes, the best way is distros add the > > ubpf packages, But maybe it's too late to implement new features for > > us. We can introduce the submodule now and auto change to the distros's > lib when distros add it. For example QEMU's submodule SLIRP do it in the > same way. > > slirp used to be part of the QEMU repository, but then has been moved to a > separate project a while ago. However, at that point in time there weren't > any packages ins distros yet, so we had to include it as a submodule. > > Now that the distros ship it, too, we're planning to remove the slirp > submodule from QEMU soon, see: > > https://lists.gnu.org/archive/html/qemu-devel/2022-04/msg00974.html > > > It make user experience the latest technology with no other > > dependencies. > > Well, that's only true if we update the submodule in QEMU regularly. If we > forget to update, we could easily miss some important (maybe even security > related) fixes from the upstream projects. This can be a nightmare for > distros, > when they then have to go around and look into each and every projects > whether they embed a certain code module that needs a CVE fix. It's better > if it can be fixed in one central spot instead. > > > uBPF infrastructure have the ability to extend the capabilities > > without requiring changing source code. If we not allow it, we have to > > re-implement all the eBPF assembler, disassembler, interpreter, and JIT > compiler like DPDK userspace eBPF support (DPDK can't use ubpf project by > license issue). > > Not sure whether I understood that statement right ... nobody said that > QEMU should not allow it - we just suggested to rely on a system installation > of ubpf instead of embedding the code. Or is that not possible?? (I don't > know that project yet - isn't it possible to compile it as a shared library?)
Thanks for your details explanation. It looks better to introduce the uBPF shared library for QEMU. For example: ./configure --ubpf-lib=path If yes, I think it's fine for me. Thanks Chen > > Thomas
