From: Aaron Conole <aconole@redhat.com>
To: Bruce Richardson <bruce.richardson@intel.com>
Cc: David Marchand <david.marchand@redhat.com>, "Ananyev\,
Konstantin" <konstantin.ananyev@intel.com>, dev <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH 0/2] remove use of weak functions from libraries
Date: Mon, 27 May 2019 16:57:15 -0400 [thread overview]
Message-ID: <f7t7eab1uqc.fsf@dhcp-25.97.bos.redhat.com> (raw)
In-Reply-To: <20190527154121.GA429@bricha3-MOBL.ger.corp.intel.com> (Bruce Richardson's message of "Mon, 27 May 2019 16:41:21 +0100")
Bruce Richardson <bruce.richardson@intel.com> writes:
> 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@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?
Yes - Sorry the patches are in my queue. Maybe it just makes sense to
merge these though?
> /Bruce
next prev parent reply other threads:[~2019-05-27 20:57 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-10 13:45 Bruce Richardson
2019-04-10 13:45 ` Bruce Richardson
2019-04-10 13:45 ` [dpdk-dev] [PATCH 1/2] acl: remove use of weak functions Bruce Richardson
2019-04-10 13:45 ` Bruce Richardson
2019-04-10 13:54 ` Aaron Conole
2019-04-10 13:54 ` Aaron Conole
2019-04-10 14:02 ` Bruce Richardson
2019-04-10 14:02 ` Bruce Richardson
2019-04-10 14:08 ` Aaron Conole
2019-04-10 14:08 ` Aaron Conole
2019-04-10 14:57 ` Ananyev, Konstantin
2019-04-10 14:57 ` Ananyev, Konstantin
2019-04-10 13:45 ` [dpdk-dev] [PATCH 2/2] bpf: " Bruce Richardson
2019-04-10 13:45 ` Bruce Richardson
2019-04-10 14:07 ` Aaron Conole
2019-04-10 14:07 ` Aaron Conole
2019-04-10 14:27 ` Bruce Richardson
2019-04-10 14:27 ` Bruce Richardson
2019-04-10 14:57 ` Ananyev, Konstantin
2019-04-10 14:57 ` Ananyev, Konstantin
2019-05-27 14:13 ` [dpdk-dev] [PATCH 0/2] remove use of weak functions from libraries David Marchand
2019-05-27 15:41 ` Bruce Richardson
2019-05-27 20:57 ` Aaron Conole [this message]
2019-05-28 8:06 ` Bruce Richardson
2019-06-05 14:41 ` Thomas Monjalon
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