On Thu, Feb 16, 2012 at 08:16:22PM -0800, Marcel Moolenaar wrote: > All, > > Juniper is in the final phases of creating a clean separation > between FreeBSD and Junos, so as to make upgrades of FreeBSD > easier. This also allows Juniper to track -current and be more > active FreeBSD contributors. > > To that end, we have a short-term and hopefully short-lived > problem to solve, which is the ability to use FreeBSD's network > drivers against the Junos network stack. As some may know, the > Junos network stack has split up struct ifnet into a physical > and logical component, called ifdev and iflogical. > > We've tried a few approaches to bridge the gap between ifnet > on the one hand and ifdev and iflogical on the other and found > that abstracting ifnet and using accessor functions is the > best way to allow us to use FreeBSD drivers with the Junos > network stack, while retaining the ability to use them with > the FreeBSD stack. > > FreeBSD is also looking at breaking up ifnet and with that in > mind, I was wondering if there would be any resistance to > changing network drivers to use accessor functions or macros > instead of direct pointer dereferences? > > For example, do something like: > > Index: if_fxp.c > =================================================================== > --- if_fxp.c (revision 231178) > +++ if_fxp.c (working copy) > @@ -823,13 +823,14 @@ > } > > if_initname(ifp, device_get_name(dev), device_get_unit(dev)); > - ifp->if_init = fxp_init; > - ifp->if_softc = sc; > - ifp->if_flags = IFF_BROADCAST | IFF_SIMPLEX | IFF_MULTICAST; > - ifp->if_ioctl = fxp_ioctl; > - ifp->if_start = fxp_start; > + if_set_init(ifp, fxp_init); > + if_set_softc(ifp, sc); > + if_set_flags(ifp, IFF_BROADCAST | IFF_SIMPLEX | IFF_MULTICAST, 0); > + if_set_ioctl(ifp, fxp_ioctl); > + if_set_start(ifp, fxp_start); > > - ifp->if_capabilities = ifp->if_capenable = 0; > + if_set_capabilities(ifp, 0); > + if_set_capenable(ifp, 0); > > /* Enable checksum offload/TSO for 82550 or better chips */ > if (sc->flags & FXP_FLAG_EXT_RFA) { > > Such a scheme, while initially touching a lot of driver, > would make it easier to break up ifnet *and* also make it > easier to hide ABI/API changes from driver vendors (esp. > when the accessor functions are non-inlined functions and > not macros or inlines). This is particularly useful for > Juniper, where we have worked towards network stacks as > (pre-)loadable modules so as to help with migration and > validation. > > Thoughts, feedback and suggestion are welcome,
I do like the idea, but the amount of changes will be massive (see below). The thing that worries me the most is that it will introduce huge changes between different releases, unless we backport the accessors (while keeping the underlying struct ifnet frozen so we preserve the kernel ABI). To count the number of lines affected, in shell: $ for i in if_addrhead if_index if_multiaddrs if_input if_output \ if_snd if_addr_lock if_init if_softc if_flags if_ioctl if_start \ if_capenable if_addr if_refcount if_fib if_drv_flags \ if_data if_index_reserved if_l2com if_link if_xname if_dname do printf "%-20s" $i; grep -r $i ~/FreeBSD/head/sys | wc -l done And you should get something like this if_addrhead 111 if_index 231 if_multiaddrs 144 if_input 184 if_output 112 if_snd 976 if_addr_lock 12 if_init 356 if_softc 1462 if_flags 1785 if_ioctl 259 if_start 194 if_capenable 1103 if_addr 324 if_refcount 6 if_fib 27 if_drv_flags 1987 if_data 202 if_index_reserved 2 if_l2com 346 if_link 187 if_xname 431 if_dname 20 cheers luigi _______________________________________________ freebsd-net@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"