Date: Fri, 22 Nov 2002 09:26:04 -0800 From: "Sam Leffler" <sam@errno.com> To: "Luigi Rizzo" <rizzo@icir.org>, "John Polstra" <jdp@polstra.com> Cc: <net@FreeBSD.ORG> Subject: Re: CFR: MFC of mtags Message-ID: <1afc01c2924c$3c811ee0$52557f42@errno.com> References: <196301c291e9$56d25e70$52557f42@errno.com> <200211221645.gAMGjKPH082267@vashon.polstra.com> <20021122091850.A81622@xorpc.icir.org>
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> i am pretty sure that this change does not affect low level drivers;
> the "any software that uses them" comment almost surely refers to the
> m_aux field, not to the entire struct mbuf.
>
> This said, fair behaviour cannot be requested to one side only.
>
> Sam posted patches, so those who have the hw/sw for which they
> suspect incompatibilities have all the resources to try the new
> code and find out whether their suspicions are founded or not.
> I am surely willing to listen to objections based on convincing
> evidence of breakage, whereas pure speculation is a much weaker
> argument.
>
John and I have been talking and there was some confusion on what might
break. To try to clarify again: this should only affect existing software
if it:
1. Calls ip_output directly.
2. Uses aux mbufs; e.g. calls m_aux*.
Network interface drivers should never do #1. If they do #2 then I'd be
very surprised, but that's what I'm searching for. John sent me an nm of
the ET driver and it does not appear to do either. I understand that folks
in this situation may have trouble verifying whether or not this patch would
break their binary drivers as they may not be running a version of the
system where this patch would apply cleanly.
Regardless, I'm waiting a week to hear from everyone and then I'll decide if
it's safe to commit the mods or not.
Sam
>
> On Fri, Nov 22, 2002 at 08:45:20AM -0800, John Polstra wrote:
> > In article <196301c291e9$56d25e70$52557f42@errno.com>, Sam Leffler
> > <sam@errno.com> wrote:
> > > I want to commit the mbuf packet tag changes to stable. These
> > > changes replace the aux mbuf pointer in the mbuf with a list of
> > > "packet tags". This does not change the size of the mbuf structure
> > > but does affect any software that uses them (presently only KAME
> > > ipsec which has been patched to use packet tags instead).
> >
> > I would strongly prefer that you not put this into the 4.x branch.
> > The project has a policy against incompatible ABI changes within the
> > -stable branch. If you do this MFC then those of us who rely on
> > third-party binary-only network drivers (such as the ET Inc. drivers,
> > upon which I and many others rely for network connectivity) will be
> > SOL. Changing the ABI within the branch is unfair to the vendors who
> > try to maintain drivers for FreeBSD, and it only discourages them from
> > trying to support our operating system. Let's just let the 4.x branch
> > live out the rest of its life span in a compatible way.
> >
> > John
> > --
> > John Polstra
> > John D. Polstra & Co., Inc. Seattle, Washington
USA
> > "Disappointment is a good sign of basic intelligence." -- Chögyam
Trungpa
> >
> >
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>
>
>
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