Date: Tue, 26 Nov 2002 17:30:11 -0800 (PST) From: Julian Elischer <julian@elischer.org> To: Robert Watson <rwatson@FreeBSD.org> Cc: arch@FreeBSD.org Subject: Re: ABIs and 5.x branch: freeze kernel module ABI at 5.0 or 5.1? Message-ID: <Pine.BSF.4.21.0211261727240.52749-100000@InterJet.elischer.org> In-Reply-To: <Pine.NEB.3.96L.1021126174032.88614J-100000@fledge.watson.org>
next in thread | previous in thread | raw e-mail | index | archive | help
I'm happy with this as long as we remember this when people want to add stuff to structures in the kernel and people yell at them :-) (e.g. the posibility of doing the virtualised network stack stuff would require that fields get added to interfaces and processes.) I still think we may save some grief by pre-loading the "usual suspects" with some "spare" fields before 5.0. Julian On Tue, 26 Nov 2002, Robert Watson wrote: > > Architectural question: in the past, we've attempted to maintain > consistent ABIs over the lifetime of a branch, or to make use of versioned > ABIs/APIs to provide compatibility. At the library level, this has > involved caution and version bumps; at the system call level, via > compatibility systems, and in the kernel, to a much lesser extent, by > avoiding changes or only lengthening structures from the end (rather than > in the middle). The ABI I'm primarily concerned with from the perspective > of this e-mail is the in-kernel ABI for modules. My concern is primarily > related to how to handle a potential ABI change in the mbuf structure, but > more broadly, whether we should be providing guarantees about the ABI > before 5.1. I'm particularly concerned that saying that we've frozen the > network driver ABIs and hardware driver ABIs as of 5.0 until 6.0 rolls > around will make it a lot harder for us to "land" 5.x into stability. > > As such, I think a reasonable strategy would be to avoid exactly that: > rather than making guarantees about the ABI for 5.0, simply assert that > the ABI for kernel drivers will not be frozen until 5.1, so vendors should > be aware that they may have to rebuild their driver. We've already > indicated that the 5.0 release will be for "early adopters"--I want to > avoid having things stand in the way of kicking the 5.x branch into shape > in as much as is possible. Any thoughts? > > Note: I really don't want to get into too broad a discussion of how we > approach ABIs and versioning: I'd rather like to get a sense of whether or > not we can assert that until 5.x is considered -STABLE, we can move the > ABI. This isn't intended to set precedent, although I'd like to avoid > foot-shooting if we can. > > Robert N M Watson FreeBSD Core Team, TrustedBSD Projects > robert@fledge.watson.org Network Associates Laboratories > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-arch" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?Pine.BSF.4.21.0211261727240.52749-100000>