On Mon, Feb 20, 2012 at 06:42:15PM -0800, Juli Mallett wrote: > On Mon, Feb 20, 2012 at 18:34, Adrian Chadd <adr...@freebsd.org> wrote: > > Is the target though _binary_ compatibility? Just having a blessed > > method of doing accessor method things will buy more source > > flexibility. The KBI can stay the same in the default case and IMHO > > this kind of thing gives developers more power to do smart invariant > > and debugging things. > > KBI compatibility requires very little discipline and makes loadable > modules for network drivers much less hellish. Inlines, macros and > full visibility of ifnet in -current may be useful, but unless there's > a performance reason for doing so, retaining KBI compatibility *and* > the ability to merge ifnet changes to -stable sounds pretty nice to > me. > > > Being able to say "inform me every time an interface flag changes" > > would actually be kind of nice when debugging some of the issues i've > > been facing with ath. I've been half tempted to do this -inside- the > > ath driver, partially to restore the OS portability it once tried to > > achieve. > > I think that it is rare that this is useful in debugging, and > something of a red herring. Even invariants are almost a red herring: > really, we shouldn't be using these individual methods to tweak > structure fields, either, we should have a way of describing a network > driver more semantically, such that the invariants are richer and also > not as complicated, and also more comprehensive. > > Source compatibility is the biggest win, but a little self-discipline > to win what measure of binary compatibility we can seems perfectly > sensible. > > (And at some point, we could even replace ifnet with something that's > less of a strange grab bag assortment that's awkward to explain to new > driver writers, and keep both source and binary compatibility for a > reasonable period in doing so. Unlikely to happen in the near term, > but wouldn't it be nice?
You could take a look how mutexes or vm_page_locks are handled, giving inlines for kernel proper and stable KBI for modules.
pgpMeq0Y5S9HJ.pgp
Description: PGP signature
