[dpdk-dev] [PATCH] mk: fix the combined library problems by replacing it with a linker script
Neil Horman
nhorman at tuxdriver.com
Tue Dec 1 14:20:27 CET 2015
On Mon, Nov 30, 2015 at 08:41:02AM -0800, Stephen Hemminger wrote:
> On Mon, 30 Nov 2015 10:03:43 -0500
> Neil Horman <nhorman at tuxdriver.com> wrote:
>
> > On Wed, Nov 25, 2015 at 08:08:37AM -0800, Stephen Hemminger wrote:
> > > On Wed, 25 Nov 2015 10:38:48 +0200
> > > Panu Matilainen <pmatilai at redhat.com> wrote:
> > >
> > > > On 11/25/2015 12:46 AM, Stephen Hemminger wrote:
> > > > > On Tue, 24 Nov 2015 16:31:17 +0200
> > > > > Panu Matilainen <pmatilai at redhat.com> wrote:
> > > > >
> > > > >> The physically linked-together combined library has been an increasing
> > > > >> source of problems, as was predicted when library and symbol versioning
> > > > >> was introduced. Replace the complex and fragile construction with a
> > > > >> simple linker script which achieves the same without all the problems,
> > > > >> remove the related kludges from eg mlx drivers.
> > > > >>
> > > > >> Since creating the linker script is practically zero cost, remove the
> > > > >> config option and just create it always.
> > > > >>
> > > > >> Based on a patch by Sergio Gonzales Monroy, linker script approach
> > > > >> initially suggested by Neil Horman.
> > > > >>
> > > > >> Suggested-by: Sergio Gonzalez Monroy <sergio.gonzalez.monroy at intel.com>
> > > > >> Suggested-by: Neil Horman <nhorman at tuxdriver.com>
> > > > >> Signed-off-by: Panu Matilainen <pmatilai at redhat.com>
> > > > >
> > > > > But it now means distros have to ship 20 libraries which seems like
> > > > > a step back.
> > > >
> > > > That's how Fedora and RHEL are shipping it already and nobody has so
> > > > much as noticed anything strange, much less complained about it. 20
> > > > libraries is but a drop in the ocean on a average distro. But more to
> > > > the point, distros will prefer 50 working libraries over one that doesn't.
> > > >
> > > > The combined library as it is simply is no longer a viable option.
> > > > Besides just being broken (witness the strange hacks people are coming
> > > > up with to work around issues in it) its ugly because it basically gives
> > > > the middle finger to all the effort going into version compatibility,
> > > > and its also big. Few projects will use every library in DPDK, but with
> > > > the combined library they're forced to lug the 800 pound gorilla along
> > > > needlessly.
> > > >
> > > > - Panu -
> > > >
> > >
> > > Fixing the combined library took less than an hour for us.
> > How did you fix the versioning issue?
> >
> > Neil
>
> This is what I did.
> Also decided to keep shared library version == major DPDK version
> to avoid confusion.
>
Ok, thats the library versioning, which is great, but I was more concerned about
the symbol versioning - i.e. the collection of version linker scripts that get
applied when you build individual libraries, but completely ignored when you
build the combined library
Neil
>
> mk: fix when building combined shared library
>
> The DPDK mk file does not set shared object name or version
> information as required by Debian.
>
> Signed-off-by: Stephen Hemminger <stephen at networkplumber.org>
>
> --- a/mk/rte.sharelib.mk
> +++ b/mk/rte.sharelib.mk
> @@ -51,10 +51,10 @@ ifeq ($(LINK_USING_CC),1)
> # Override the definition of LD here, since we're linking with CC
> LD := $(CC) $(CPU_CFLAGS)
> O_TO_S = $(LD) $(call linkerprefix,$(CPU_LDFLAGS)) \
> - -shared $(OBJS) -o $(RTE_OUTPUT)/lib/$(LIB_ONE)
> + -shared $(OBJS) -Wl,-soname,$(LIB_ONE).$(RTE_LIBVERS) -o $(RTE_OUTPUT)/lib/$(LIB_ONE)
> else
> O_TO_S = $(LD) $(CPU_LDFLAGS) \
> - -shared $(OBJS) -o $(RTE_OUTPUT)/lib/$(LIB_ONE)
> + -shared $(OBJS) -soname $(LIB_ONE).$(RTE_LIBVERS) -o $(RTE_OUTPUT)/lib/$(LIB_ONE)
> endif
>
> O_TO_S_STR = $(subst ','\'',$(O_TO_S)) #'# fix syntax highlight
> --- a/mk/rte.vars.mk
> +++ b/mk/rte.vars.mk
> @@ -74,8 +74,10 @@ ifneq ($(BUILDING_RTE_SDK),)
> endif
>
> RTE_LIBNAME := $(CONFIG_RTE_LIBNAME:"%"=%)
> +RTE_LIBVERS := $(CONFIG_RTE_LIBVERS:"%"=%)
> ifeq ($(RTE_LIBNAME),)
> RTE_LIBNAME := intel_dpdk
> +RTE_LIBVERS := 2
> endif
>
> # RTE_TARGET is deducted from config when we are building the SDK.
>
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