Date: Sat, 27 Jul 2002 11:53:36 +0200 From: Andre Oppermann <oppermann@pipeline.ch> To: Brooks Davis <brooks@one-eyed-alien.net> Cc: net@freebsd.org Subject: Re: switching to if_xname from if_name and if_unit Message-ID: <3D426DA0.923B7F81@pipeline.ch> References: <20020726211050.A30598@Odin.AC.HMC.Edu>
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Brooks Davis wrote:
>
> [Bcc to -arch for interested people not on -net]
>
> NetBSD and OpenBSD have replaced the "char *if_name" and "int if_unit"
> members of struct ifnet with "char if_xname[IFNAMESIZ]". I propose that
> we follow suit.
>
> Pros:
> - Better source compatibility with NetBSD and OpenBSD.
> - The ability to handle free-form device names. This could allow
> things like and advanced cloning interface for vlans that let you
> configure vlan X on interface nameY with "ifconfig nameY.X create".
I like this one ;-) I vote yes for doing this change.
--
Andre
> - Most uses of if_name and if_unit together really just want the full
> name of the device and the same with the majority of if_unit
> entries. The remaining if_unit usages are usually the result of
> sloppy code with hard wired limits on the number of devices that
> should be fixed.
> - We can implement the if_name() function without the current gross
> hacks.
> - Well defined maximum name size simplifies code.
>
> Cons:
> - Lost of source compatibility between 5.x and previous versions.
> [We've already lost it with the spls and in most drivers it's
> a two line change that you could handle with __FreeBSD_version if
> you wanted to.]
> - A few devices do have a legitimate use for use for the unit. [They
> can use the softc to store it. That's what NetBSD did.]
> - Well defined maximum name size limits length of name. [It's 16
> bytes with is more then I'd want to type in to ifconfig.]
> - It touches 140-150 files. [Most of the changes are minor in nature
> and I'm about halfway through with 2-3hrs of work.]
> - Slight bloating of struct ifnet (8 bytes on normal 32-bit
> architectures). [None on 64-bit arches.]
> - We've resisted for 8 years, we can't stop now. :-)
>
> What do other people think?
>
> -- Brooks
>
> PS. Here the diff for a typical interface (around half have only the
> initialization change and most others have more, but similar debugging
> output changes):
>
> RCS file: /usr/cvs/src/sys/dev/ep/if_ep.c,v
> retrieving revision 1.109
> diff -u -p -r1.109 if_ep.c
> --- ep/if_ep.c 20 Mar 2002 02:07:19 -0000 1.109
> +++ ep/if_ep.c 26 Jul 2002 06:55:58 -0000
> @@ -280,8 +280,7 @@ ep_attach(sc)
> attached = (ifp->if_softc != 0);
>
> ifp->if_softc = sc;
> - ifp->if_unit = sc->unit;
> - ifp->if_name = "ep";
> + sprintf(ifp->if_xname, "ep%d", sc->unit);
> ifp->if_mtu = ETHERMTU;
> ifp->if_flags = IFF_BROADCAST | IFF_SIMPLEX | IFF_MULTICAST;
> ifp->if_output = ether_output;
> @@ -917,7 +916,7 @@ ep_if_watchdog(ifp)
> /*
> printf("ep: watchdog\n");
>
> - log(LOG_ERR, "ep%d: watchdog\n", ifp->if_unit);
> + log(LOG_ERR, "%s: watchdog\n", ifp->if_xname);
> ifp->if_oerrors++;
> */
>
>
> --
> Any statement of the form "X is the one, true Y" is FALSE.
> PGP fingerprint 655D 519C 26A7 82E7 2529 9BF0 5D8E 8BE9 F238 1AD4
>
> ------------------------------------------------------------------------
> Part 1.2Type: application/pgp-signature
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