Re: [dpdk-dev] [PATCH 0/2] remove use of weak functions from libraries

[Thomas Monjalon <thomas@monjalon.net>]

10/04/2019 15:45, Bruce Richardson:
> Weak functions don't work well with static library builds as the linker
> always picks the first version of a function irrespective of whether it is
> weak or not. The solution to this is to use the "whole-archive" flag when
> linking, but this has the nasty side-effect that it causes the resulting
> binary to be larger than it needs to be.
> 
> 
> A further problem with this approach of using "whole-archive" is that one
> either needs to link all libraries with this flag or track what libraries
> need it or not - the latter being especially a problem for apps not using
> the DPDK build system itself (i.e. most apps not shipped with DPDK itself).
> For meson builds this information needs to make its way all the way through
> to the pkgconfig file generated - not a trivial undertaking.
> 
> Thankfully, though, the use of weak functions is limited to use for
> multiple functions within a single library, meaning that when the lib is
> being built, the build system itself can know whether the "weak" function
> is needed or not. This allows us to change the weak function to a
> conditionally compiled regular function used in fallback case. This makes
> the need for "whole-archive" flag, and any special linking measures for the
> library, go away.
> 
> [This set does not touch the drivers, only the libraries, since there are
> other special linker flags needed for drivers in general, making the
> problem less severe for driver .a files.]
> 
> Bruce Richardson (2):
>   acl: remove use of weak functions
>   bpf: remove use of weak functions

Applied, thanks