On Mon, Nov 4, 2013 at 11:51 AM, Luigi Rizzo <ri...@iet.unipi.it> wrote: > On Mon, Nov 04, 2013 at 10:20:12AM -0800, Anthony Liguori wrote: >> On Mon, Nov 4, 2013 at 10:08 AM, Luigi Rizzo <ri...@iet.unipi.it> wrote: > ... >> >> On Tue, Oct 29, 2013 at 3:12 AM, Vincenzo Maffione <v.maffi...@gmail.com> >> >> wrote: >> >> > This patch adds support for a network backend based on netmap. >> >> > netmap is a framework for high speed packet I/O. You can use it >> >> > to build extremely fast traffic generators, monitors, software >> >> > switches or network middleboxes. Its companion software switch >> >> > VALE lets you interconnect virtual machines. >> >> > netmap and VALE are implemented as a non intrusive kernel module, >> >> > support NICs from multiple vendors, are part of standard FreeBSD >> >> > distributions and available in source format for Linux too. >> >> >> >> I don't think it's a good idea to support this on Linux hosts. This >> >> is an out of tree module that most likely will never go upstream. >> >> >> >> I don't want to live through another kqemu with this if it eventually >> >> starts to bit-rot. >> > >> > >> > I believe this is very different from kqemu. >> > >> > For first, it is just a one-file backend (the patches >> > to other files are just because there is not yet a way >> > to automatically generate them; but i am sure qemu >> > will get there). Getting rid of it, should the code >> > bit-rot, is completely trivial. >> > >> > Second, there is nothing linux specific here. Unless configure >> > determines that the (possibly out of tree, as in Linux, >> > or in-tree, as in FreeBSD) netmap headers are >> > installed, it just won't build the backend. >> >> Without being in upstream Linux, we have no guarantee that the API/ABI >> will be stable over time. I suspect it's also very unlikely that any >> many stream distro will include these patches meaning that the number >> of users that will test this is very low. >> >> I don't think just adding another backend because we can helps us out >> in the long term. Either this is the Right Approach to networking and >> we should focus on getting proper kernel support or if that's not >> worth it, then there's no reason to include this in QEMU either. > > anthony, > i'd still like you to answer the question that i asked before: > > are you opposed to netmap support just for linux, or you > oppose to it in general (despite netmap being already > upstream in FreeBSD) ? > > Your reasoning seems along the lines "if feature X is not upstream > in linux we do not want to support it".
Yes. This is the historic policy we have taken for any feature. I have no problem with netmap being used on FreeBSD hosts but I think it should not be enabled on Linux hosts. Regards, Anthony Liguori
