[dpdk-dev] [PATCH 0/2] remove use of weak functions from libraries
Bruce Richardson
bruce.richardson at intel.com
Mon May 27 17:41:21 CEST 2019
On Mon, May 27, 2019 at 04:13:53PM +0200, David Marchand wrote:
> Hello,
> On Wed, Apr 10, 2019 at 3:45 PM Bruce Richardson
> <[1]bruce.richardson at intel.com> wrote:
>
> 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.]
>
> Was there something preventing this patchset from getting merged ?
> --
> David Marchand
>
I believe Aaron Conole had some changes in the same area and was looking to
roll these changes into a bigger patchset of his. Aaron, can you please
confirm?
/Bruce
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