Re: [Qemu-devel] net: Adding netmap network backend

[Vincenzo Maffione]

Yes, for sure we need to do a check.

However, this would involve - I think - some non-trivial modifications to net/netmap.c, because without NS_MOREFRAG you cannot split a packet over more "netmap slots/descriptors" (both tx and rx side)

Therefore I would ask (manly Luigi, since netmap is in-tree in FreeBSD): Wouldn't it be better to force --disable-netmap when we realize that NETMAP_API (version number for the netmap API) is less than the value required by QEMU? This can be done in ./configure. In this way we keep the QEMU code cleaner.

Thanks,

  Vincenzo

2014-02-14 10:52 GMT+01:00 Stefan Hajnoczi <address@hidden>:

On Wed, Feb 12, 2014 at 10:01:01PM +0400, Michael Tokarev wrote:
> After this patch, qemu fails to build on freebsd with the following
> error message:
>
> net/netmap.c: In function 'netmap_receive_iov':
> net/netmap.c:307: error: 'NS_MOREFRAG' undeclared (first use in this function)
> net/netmap.c:307: error: (Each undeclared identifier is reported only once
> net/netmap.c:307: error: for each function it appears in.)
> net/netmap.c: In function 'netmap_send':
> net/netmap.c:356: error: 'NS_MOREFRAG' undeclared (first use in this function)
> gmake: *** [net/netmap.o] Error 1
>
> I didn't enable netmap support by default, configure enabled it
> automatically.
>
> Freebsd has /usr/include/net/netmap.h and netmap_user.h out of the box.
> I've no idea what is inside and how compatible it is with whatever
> qemu expects.
>
> I had to explicitly use --disable-netmap for qemu to build on freebsd.
>
> This is FreeBSD 9.1-RELEASE, FWIW.

Vincenzo: Do you need to add a ./configure check so NS_MOREFRAG is only
used when the host kernel supports it?

--
Vincenzo Maffione