Re: [PATCH] hash: make gfni stubs inline

[Stephen Hemminger <stephen@networkplumber.org>]

On Thu, 7 Mar 2024 11:32:36 +0100
David Marchand <david.marchand@redhat.com> wrote:

> On Tue, Mar 5, 2024 at 6:53 PM Tyler Retzlaff
> <roretzla@linux.microsoft.com> wrote:
> >
> > On Tue, Mar 05, 2024 at 11:14:45AM +0100, David Marchand wrote:  
> > > On Mon, Mar 4, 2024 at 7:45 PM Stephen Hemminger
> > > <stephen@networkplumber.org> wrote:  
> > > >
> > > > This reverts commit 07d836e5929d18ad6640ebae90dd2f81a2cafb71.
> > > >
> > > > Tyler found build issues with MSVC and the thash gfni stubs.
> > > > The problem would be link errors from missing symbols.  
> > >
> > > Trying to understand this link error.
> > > Does it come from the fact that rte_thash_gfni/rte_thash_gfni_bulk
> > > declarations are hidden under RTE_THASH_GFNI_DEFINED in
> > > rte_thash_gfni.h?
> > >
> > > If so, why not always expose those two symbols unconditionnally and
> > > link with the stub only when ! RTE_THASH_GFNI_DEFINED.  
> >
> > So I don't have a lot of background of this lib.
> >
> > I think we understand that we can't conditionally expose symbols. That's
> > what windows was picking up because it seems none of our CI's ever end
> > up with RTE_THASH_GFNI_DEFINED but my local test system did and failed.
> > (my experiments showed that Linux would complain too if it was defined)  
> 
> I can't reproduce a problem when I build (gcc/clang) for a target that
> has GFNI/AVX512F.
> binutils ld seems to just ignore unknown symbols in the map.


Turns out MSVC linker does not. That is why Tyler complained.