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Date:      Sun, 3 Oct 2010 00:29:21 +0100
From:      Rui Paulo <rpaulo@freebsd.org>
To:        Juli Mallett <jmallett@FreeBSD.org>
Cc:        Ryan Stone <rysto32@gmail.com>, Robert Watson <rwatson@freebsd.org>, FreeBSD Net <net@freebsd.org>
Subject:   Re: mbuf changes
Message-ID:  <0DB8120D-C02A-49A1-8013-1ED818EDE7E6@freebsd.org>
In-Reply-To: <AANLkTi=uxARo5O9MASrx9mg-39E2=x05RXxcKUB62JrB@mail.gmail.com>
References:  <4C9DA26D.7000309@freebsd.org> <AANLkTim7oRyVYY3frn7=cn4Et8Acbcq9cXja_bR6YWvP@mail.gmail.com> <4CA51024.8020307@freebsd.org> <alpine.BSF.2.00.1010021627230.49031@fledge.watson.org> <9AD4923A-72AE-4FE3-A869-3AF8ECBF17E2@FreeBSD.org> <AANLkTi=uxARo5O9MASrx9mg-39E2=x05RXxcKUB62JrB@mail.gmail.com>

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On 2 Oct 2010, at 21:35, Juli Mallett wrote:

> On Sat, Oct 2, 2010 at 12:07, Rui Paulo <rpaulo@freebsd.org> wrote:
>> On 2 Oct 2010, at 16:29, Robert Watson wrote:
>>> On Thu, 30 Sep 2010, Julian Elischer wrote:
>>>> On 9/30/10 10:49 AM, Ryan Stone wrote:
>>>>> It's not a big thing but it would be nice to replace the m_next =
and m_nextpkt fields with queue.h macros.
>>>> funny, I've never even thought of that..
>>>=20
>>> I have, and it's a massive change touching code all over the kernel =
in vast quantities.  While in principle it's a good idea (consistently =
avoid hand-crafted linked lists), it's something I'd discourage on the =
basis that it probably won't significant reduce the kernel bug count, =
but will make it even harder for vendors with large local changes to the =
network stack to keep up.
>>=20
>> I think it could also increase the kernel bug count. Unfortunately, =
we can't do this incrementally.
>=20
> Can't we?  What about a union, so that we can gradually convert things
> but keep ABI and API compatibility?  I mean, as long as we use the
> right queue.h type, anyway, it should be consistent?  STAILQ,
> presumably.

Well, I don't have the layout of the mbuf struct offhand, but it's an =
idea worth investigating.

Regards,
--
Rui Paulo





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