Date: Thu, 01 Mar 2007 11:05:28 +0000 From: "Bruce M. Simpson" <bms@FreeBSD.org> To: Bruce M Simpson <bms@incunabulum.net> Cc: net@FreeBSD.org Subject: Re: Proposal: Add M_HASCL(). Message-ID: <45E6B378.1020703@FreeBSD.org> In-Reply-To: <45E60041.1090607@incunabulum.net> References: <45E60041.1090607@incunabulum.net>
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Bruce M Simpson wrote: > Much network code needs to know if the mbuf it is looking at is using > a cluster. I propose putting M_HASCL() in sys/mbuf.h. I realise this > is a style change, however, it seems to be a very common idiom. I sent this, then I looked at NetBSD, having caught a glimpse of their MBUFTRACE code when skimming lots of diffs. That is also a good idea, and might help us catch problems before they go prime-time; I've added it to the wiki. Point there is, M_HASCL() seems to be a hangover from the 4.4BSD era. NetBSD seems to treat clusters and external storage as separate entities. So I'm reconsidering this in the light of this new evidence. As far as I understand it, the presence of M_EXT in an mbuf chain's header in FreeBSD always indicate that we are using external storage (not necessarily, but possibly, a cluster). Can someone confirm this? Regards, BMS
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