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

[Bruce Richardson <bruce.richardson@intel.com>]

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?