Re: [dpdk-dev] [PATCH v2] build: avoid --as-needed as it causes overlinking

[Luca Boccassi <bluca@debian.org>]

On Thu, 2019-08-29 at 16:34 +0100, Bruce Richardson wrote:
> On Thu, Aug 29, 2019 at 05:30:03PM +0200, Christian Ehrhardt wrote:
> > A while ago telemetry was added in 57ae0ec6 and it also added as-
> > needed
> > to config/meson.build. This seems no more needed these days as due
> > to other
> > build changes the ordering in buildlogs is:
> >   [...] -lrte_telemetry [...] -Wl,--no-as-needed [...]
> > Which means telemetry no more benefits from --no-as-needed anyway.
> > 
> > Overlinking problems get triggered by the meson generated pkgconfig
> > which
> > will have:
> >    [...] -Wl,--no-as-needed <somelibsusedbydpdk>
> > This will overlink <somelibs> and in addition anything that follows
> > as it also doesn't wrap back to --as-needed. So if a projects
> > includes
> > dpdk libs + <other> it will also consider <other> with --no-as-
> > needed.
> > 
> > Fixes: 
> > https://bugs.launchpad.net/ubuntu/+source/dpdk/+bug/1841759
> > 
> > 
> > Signed-off-by: Christian Ehrhardt <
> > christian.ehrhardt@canonical.com
> > >
> > Acked-by: Luca Boccassi <
> > bluca@debian.org
> > >
> > ---
> >  config/meson.build | 1 -
> >  1 file changed, 1 deletion(-)
> > 
> > diff --git a/config/meson.build b/config/meson.build
> > index 2bafea530..a27f731f8 100644
> > --- a/config/meson.build
> > +++ b/config/meson.build
> > @@ -94,7 +94,6 @@ dpdk_conf.set('RTE_TOOLCHAIN_' +
> > toolchain.to_upper(), 1)
> >  dpdk_conf.set('RTE_ARCH_64', cc.sizeof('void *') == 8)
> >  
> >  add_project_link_arguments('-Wl,--no-as-needed', language: 'c')
> > -dpdk_extra_ldflags += '-Wl,--no-as-needed'
> >  
> 
> This seems strange to me. What is it about linking the dpdk apps that
> require the argument, but makes it safe for non-builtin apps to avoid
> having the arg?

We've been wondering about that for a while :-) It also seems to be not
reproducible on Ubuntu 18.04/gcc 7.4.

Can the verbose linking log be shared here, so that we can have a look
at where no-as-needed lands? Might provide some clue

-- 
Kind regards,
Luca Boccassi