-current build failure

[Konstantin Belousov]

On Fri, Jul 20, 2012 at 05:40:32PM +0200, Dimitry Andric wrote:
> On 2012-07-20 16:49, Kim Culhan wrote:
> >  Seeing this for r:238655
> ...
> > In file included from /usr/src/sys/modules/dtrace/dtrace/../../../sys/pcpu.h:44:
> > ./machine/pcpu.h:226:13: error: indirection of non-volatile null
> > pointer will be deleted, not trap
> >       [-Werror,-Wnull-dereference]
> >             : "m" (*(char *)OFFSETOF_CURTHREAD));
> >                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~
> > ./machine/pcpu.h:226:13: note: consider using __builtin_trap() or
> > qualifying pointer with 'volatile'
> 
> That's indeed a valid warning from clang, since OFFSETOF_CURTHREAD is
> usually zero.  It's probably due to recent work on dtrace.  I'm not in
> the neighborhood of a FreeBSD box right now to verify, but can you
> please try to change the cast to "(volatile char *)"?  That should fix
> the warning.

It is not related to dtrace at all, and indeed OFFSETOF_CURTHREAD is 0.
This is a bug in clang, we compile our kernel in freestanding environment.
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