Re: [Xen-devel] [PATCH 30/34] xen: Add missing includes on different files

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2014-03-27 at 17:47 +0000, Julien Grall wrote:
> On 03/27/2014 05:39 PM, Ian Campbell wrote:
> > On Thu, 2014-03-27 at 17:30 +0000, Julien Grall wrote:
> >> On 03/27/2014 05:11 PM, Ian Campbell wrote:
> >>> On Tue, 2014-03-25 at 16:55 +0000, Julien Grall wrote:
> >>>> This was spotted by -Wmissing-prototypes, which we can't enable because 
> >>>> there
> >>>> is exported function for assembly. I'm not sure if we need to add a 
> >>>> prototype
> >>>> for them.
> >>>
> >>> What exactly is the issue here?
> >>
> >> There a bunch of functions (see below for ARM) where the prototype is
> >> not defined before. Mainly because theses functions are used by the
> >> assembly code so we don't need to give a prototype.
> >>
> >> do_trap_*
> >> start_xen
> >> start_secondary
> >> leave_hypervisor_tail
> > 
> > Is that all of them? Although their prototypes are useless there are few
> > enough of them that the benefit of being able to turn on
> > Wmissing-prototypes might make it worth it.
> 
> From the common code there is 7 others:
> 
> core_parking_helper and get_cur_idle_nums (both of them are used on C
> code but never defined in an header. I was lazy and I didn't write a patch).
> 
> __qdivrem
> __divdi3
> __umoddi3
> __moddi3
> __ldivmod_helper

Still not awful I guess.

Several of these are essentially library functions provided for the
compiler to emit calls to, I wonder if there is some compiler header
which we should be including which would prototype them. Probably not,
worth a look though.

> 
> For x86, I didn't yet try to compiled it with -Wmissing-prototypes.
> 
> > 
> > Unless there is some attribute we can apply which marks these as not
> > requiring a prototype?
> 
> I will look at it.

Thanks.

> > Even better if as a side effect the compiler will
> > warn about calls not from assembly...
> 
> I would love to see this feature, but I don't think the linker is able
> to differentiate call from C and from assembly :).

The compiler could see a call from C code to a function whose prototype
was marked with "called_from_asm_only".

Ian.


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