Re: [Qemu-devel] Is network backend netmap worth keeping?

[Giuseppe Lettieri]

Il 13/09/19 15:04, Markus Armbruster ha scritto:
> What happens when I build with --enable-netmap=system on host A, then
> run the resulting binary on some host B that doesn't have netmap
> installed?

Qemu will fail at startup, complaining that /dev/netmap does not exists.


> Yes.  We default to netmap=system, though.  If you break things by
> passing arcane arguments to configure, you get to keep the pieces :)
>
> > If the option is only useful for developers to check that some qemu
> > change does not break anything, then probably it should be enabled in
> > some other, less visible way. What do you think?
>
> I think an --enable-netmap patterned after --enable-capstone and
> --enable-slirp has sufficiently low visibility as long as the default is
> sane.
>
> We clearly want configure to pick netmap=system when the system provides
> netmap.
>
> What shall configure pick when the system doesn't provide it?  If you
> think netmap=git is too dangerous for general audience, consider
> disabling netmap then.  Experts can still compile-test with
> --enable-netmap=git.  Our CI certainly should.

OK, sounds reasonable. The attached patch will select system if netmap 
is available, and git only if explicitly requested.

Cheers,
Giuseppe

--
Dr. Ing. Giuseppe Lettieri
Dipartimento di Ingegneria della Informazione
Universita' di Pisa
Largo Lucio Lazzarino 1, 56122 Pisa - Italy
Ph. : (+39) 050-2217.649 (direct) .599 (switch)
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e-mail: address@hidden

0001-netmap-support-git-submodule-build-otption.patch
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