Date: Thu, 3 Jun 2004 16:02:45 +0200 From: Christian Weisgerber <naddy@mips.inka.de> To: Andrew Thompson <andy@fud.org.nz> Cc: freebsd-current@FreeBSD.org Subject: Re: Network driver jumbo patch (affects multicast) Message-ID: <20040603140245.GA79548@kemoauc.mips.inka.de> In-Reply-To: <20040603012501.GA5035@thingy.tbd.co.nz> References: <c9ltb3$13cb$1@kemoauc.mips.inka.de> <20040603012501.GA5035@thingy.tbd.co.nz>
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Andrew Thompson: > You have removed the following comment from if_xl.c. The two notes are > still relevant, should they stay? > > - * Note: the 3c905B currently only supports a 64-bit hash table, > - * which means we really only need 6 bits, but the manual indicates > - * that future chip revisions will have a 256-bit hash table, > - * hence the routine is set up to calculate 8 bits of position > - * info in case we need it some day. > - * Note II, The Sequel: _CURRENT_ versions of the 3c905B have a > - * 256 bit hash table. This means we have to use all 8 bits regardless. > - * On older cards, the upper 2 bits will be ignored. Grrrr.... I think it's just rambling. I mean, it says that (1) the specs tell us to use the lower eight bits of the hash, and (2) that's what the driver does. That some early production run 3C905Bs (just how many years ago?) ignored the two upper bits is irrelevant trivia. NetBSD also uses the lower eight bits. Now, a more interesting question is why OpenBSD uses the upper six bits... -- Christian "naddy" Weisgerber naddy@mips.inka.de
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