On Mon, 1 Oct 2001, Matthew Jacob wrote:
> Yes- this may have been true for a long time - but quite a number of
> Unix variants don't require it, so I forgot :-).. For example, neither
> OpenBSD nor NetBSD seem to require it.
>
> It turns out that this is only stumbled on rarely- but if it's all the same to
> you, a comment would help a lot.
It looks like storing a pointer to struct arpcom in struct ifnet might
solve most of the cases where ifp->if_softc == struct arpcom/struct
ifnet. I'm not exactly sure how to deal with the miibus stuff at this
point; the following, in mii.c:miibus_linkchg():
mii = device_get_softc(dev);
ifp = device_get_softc(parent);
can be changed to:
mii = device_get_softc(dev);
ifp = mii->mii_ifp;
I'm thinking we could pass struct ifnet in to mii.c:mii_phy_probe() and
attach it to the device ivars.
> On Mon, 1 Oct 2001, Julian Elischer wrote:
>
> > Not only that but the ifnet structure must be the first part of the arpcom
> > struct so that arpcm, ifnet and softc often need to be the same.. I've
> > been gradually trying to remove this requirement over the last 10 years
> > but it's still there.. :-/
> >
> > Comments can't hurt though..
> >
> >
> > On Mon, 1 Oct 2001, Matthew Jacob wrote:
> >
> > >
> > > This bit me in the butt yet again about FreeBSD and some assumptions about how
> > > a NIC's softc is laid out- I don't really it stated elsewhere, so a couple
> > > source file comments seem in order.. Frankly, this kind of assumption is
> > > dangerous and unnecessary with methods, but at the very least it ought to be
> > > commented, no?
> > >
> > > -matt
> > >
> > >
> > > Index: net/if_var.h
> > > ===================================================================
> > > RCS file: /home/ncvs/src/sys/net/if_var.h,v
> > > retrieving revision 1.37
> > > diff -u -r1.37 if_var.h
> > > --- net/if_var.h 2001/09/18 17:41:42 1.37
> > > +++ net/if_var.h 2001/10/01 20:00:08
> > > @@ -105,6 +105,11 @@
> > > *
> > > * (Would like to call this struct ``if'', but C isn't PL/1.)
> > > */
> > > +
> > > +/*
> > > + * NB: For FreeBSD, it is assumed that each NIC driver's softc starts with
> > > + * one of these structures, typically held within an arpcom structure.
> > > + */
> > > struct ifnet {
> > > void *if_softc; /* pointer to driver state */
> > > char *if_name; /* name, e.g. ``en'' or ``lo'' */
> > > Index: dev/mii/mii.c
> > > ===================================================================
> > > RCS file: /home/ncvs/src/sys/dev/mii/mii.c,v
> > > retrieving revision 1.9
> > > diff -u -r1.9 mii.c
> > > --- dev/mii/mii.c 2001/09/29 18:40:06 1.9
> > > +++ dev/mii/mii.c 2001/10/01 20:00:09
> > > @@ -167,6 +167,9 @@
> > > struct mii_data *mii;
> > >
> > > mii = device_get_softc(dev);
> > > + /*
> > > + * Note that each NIC's softc must start with an ifnet structure.
> > > + */
> > > mii->mii_ifp = device_get_softc(device_get_parent(dev));
> > > v = device_get_ivars(dev);
> > > ifmedia_upd = v[0];
> > > @@ -233,6 +236,9 @@
> > > MIIBUS_LINKCHG(parent);
> > >
> > > mii = device_get_softc(dev);
> > > + /*
> > > + * Note that each NIC's softc must start with an ifnet structure.
> > > + */
> > > ifp = device_get_softc(parent);
> > >
> > > if (mii->mii_media_status & IFM_AVALID) {
> > >
> > >
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> > >
> >
> >
>
>
>
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--
| Matthew N. Dodd | '78 Datsun 280Z | '75 Volvo 164E | FreeBSD/NetBSD |
| [EMAIL PROTECTED] | 2 x '84 Volvo 245DL | ix86,sparc,pmax |
| http://www.jurai.net/~winter | For Great Justice! | ISO8802.5 4ever |
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