Re: finishing the if.h/if_var.h split

From: Bruce Evans (bde_at_zeta.org.au)
Date: 09/30/03

  • Next message: John Baldwin: "Re: finishing the if.h/if_var.h split" 
    Date: Wed, 1 Oct 2003 01:29:07 +1000 (EST)
To: John Baldwin <jhb@freebsd.org>

    On Tue, 30 Sep 2003, John Baldwin wrote:

    > On 30-Sep-2003 Bruce Evans wrote:
    > > On Mon, 29 Sep 2003, Brooks Davis wrote:
    > >> Unfortunately, "soon" hasn't happened yet and it is now tripping me
    > >> up. To add the if_dev member to struct ifnet (see the forthcoming
    > >> post on that subject), it is necessary for sys/bus.h to be included in
    > >> net/if_var.h
    > >
    > > That would be namespace pollution, so it is not permitted :-). Requiring
    > > all files that include <sys/if_var.h> (and especially <sys/if.h> to
    > > include <sys/bus.h> would be interface breakage so it is even less
    > > permitted.
    >
    > Well, if if.h stops including if_var.h, then only kernel files that
    > include net/if_var.h would need sys/bus.h. I think that's manageable.

    All userland files that include net/if_var.h would also need it (except
    they would only need device_t).

    > >> which in turn requires that if_var.h NOT be included in
    > >> genassym.c.
    > >
    > > Do you mean in userland? There don't seem to be any immediate problems
    > > for genassym.c or any other file in the kernel from including <sys/bus.h>
    > > unconditionally in <net/if_var.h>. However, the pollution may be harmful
    > ...
    > The problem is that the newbus foo_if.h files don't exist when genassym
    > is compiled and used. sys/bus.h needs bus_if.h and device_if.h, hence
    > the breakage.

    I see. This is a bug in the dependencies for genassym.o and .depend.
    "make depend" creates *_if.h but it also creates genassym.o. There aren't
    enough dependencies so the order is mostly accidental. genassym.o happens
    to get created first, so it doesn't compile unless *_if.h already exist.

    Bruce
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