Date: Tue, 20 Apr 2010 23:55:27 +0200 From: Luigi Rizzo <rizzo@iet.unipi.it> To: net@freebsd.org Subject: Re: max_linkhdr defaults to 16, too short ? Message-ID: <20100420215527.GA75324@onelab2.iet.unipi.it> In-Reply-To: <20100420172845.GA71187@onelab2.iet.unipi.it> References: <20100420172845.GA71187@onelab2.iet.unipi.it>
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On Tue, Apr 20, 2010 at 07:28:45PM +0200, Luigi Rizzo wrote: > just noticed that sys/kern/uipc_domain.c still sets max_linkhdr=16 > as a default. > The value is often used to reserve head space in mbufs for > the MAC header. As such, 16 is too short for systems that make > use of vlans, and the effect might be that we would need > additional mbuf entries or at least move stuff down > as the vlan tag is added. > > Any objection to bumping the default to 20 ? forgot to mention: max_linkhdr is available as a sysctl, kern.max_linkhdr , but other than that, there is no code in sys/ that sets the value, so systems are stuck at 16 unless users override the default. cheers luigi
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