[dpdk-dev] [PATCH v2] mk: Provide option to set Major ABI version

[Jan Blunck]

On Wed, Mar 1, 2017 at 10:34 AM, Christian Ehrhardt
<christian.ehrhardt at canonical.com> wrote:
> Downstreams might want to provide different DPDK releases at the same
> time to support multiple consumers of DPDK linked against older and newer
> sonames.
>
> Also due to the interdependencies that DPDK libraries can have applications
> might end up with an executable space in which multiple versions of a
> library are mapped by ld.so.
>
> Think of LibA that got an ABI bump and LibB that did not get an ABI bump
> but is depending on LibA.
>
>     Application
>     \-> LibA.old
>     \-> LibB.new -> LibA.new
>
> That is a conflict which can be avoided by setting CONFIG_RTE_MAJOR_ABI.
> If set CONFIG_RTE_MAJOR_ABI overwrites any LIBABIVER value.
> An example might be ``CONFIG_RTE_MAJOR_ABI=16.11`` which will make all
> libraries librte<?>.so.16.11 instead of librte<?>.so.<LIBABIVER>.
>
> We need to cut arbitrary long stings after the .so now and this would work
> for any ABI version in LIBABIVER:
>   $(Q)ln -s -f $< $(patsubst %.$(LIBABIVER),%,$@)
> But using the following instead additionally allows to simplify the Make
> File for the CONFIG_RTE_NEXT_ABI case.
>   $(Q)ln -s -f $< $(shell echo $@ | sed 's/\.so.*/.so/')
>
> Signed-off-by: Christian Ehrhardt <christian.ehrhardt at canonical.com>
> ---
>  config/common_base                     |  5 +++++
>  doc/guides/contributing/versioning.rst | 25 +++++++++++++++++++++++++
>  mk/rte.lib.mk                          | 14 +++++++++-----
>  3 files changed, 39 insertions(+), 5 deletions(-)
>
> diff --git a/config/common_base b/config/common_base
> index aeee13e..37aa1e1 100644
> --- a/config/common_base
> +++ b/config/common_base
> @@ -75,6 +75,11 @@ CONFIG_RTE_BUILD_SHARED_LIB=n
>  CONFIG_RTE_NEXT_ABI=y
>
>  #
> +# Major ABI to overwrite library specific LIBABIVER
> +#
> +CONFIG_RTE_MAJOR_ABI=
> +
> +#
>  # Machine's cache line size
>  #
>  CONFIG_RTE_CACHE_LINE_SIZE=64
> diff --git a/doc/guides/contributing/versioning.rst b/doc/guides/contributing/versioning.rst
> index fbc44a7..8aaf370 100644
> --- a/doc/guides/contributing/versioning.rst
> +++ b/doc/guides/contributing/versioning.rst
> @@ -133,6 +133,31 @@ The macros exported are:
>    fully qualified function ``p``, so that if a symbol becomes versioned, it
>    can still be mapped back to the public symbol name.
>
> +Setting a Major ABI version
> +---------------------------
> +
> +Downstreams might want to provide different DPDK releases at the same time to
> +support multiple consumers of DPDK linked against older and newer sonames.
> +
> +Also due to the interdependencies that DPDK libraries can have applications
> +might end up with an executable space in which multiple versions of a library
> +are mapped by ld.so.
> +
> +Think of LibA that got an ABI bump and LibB that did not get an ABI bump but is
> +depending on LibA.
> +
> +.. note::
> +
> +    Application
> +    \-> LibA.old
> +    \-> LibB.new -> LibA.new
> +
> +That is a conflict which can be avoided by setting ``CONFIG_RTE_MAJOR_ABI``.
> +If set, the value of ``CONFIG_RTE_MAJOR_ABI`` overwrites all - otherwise per
> +library - versions defined in the libraries ``LIBABIVER``.
> +An example might be ``CONFIG_RTE_MAJOR_ABI=16.11`` which will make all libraries
> +``librte<?>.so.16.11`` instead of ``librte<?>.so.<LIBABIVER>``.
> +
>  Examples of ABI Macro use
>  -------------------------
>
> diff --git a/mk/rte.lib.mk b/mk/rte.lib.mk
> index 33a5f5a..1ffbf42 100644
> --- a/mk/rte.lib.mk
> +++ b/mk/rte.lib.mk
> @@ -40,12 +40,20 @@ EXTLIB_BUILD ?= n
>  # VPATH contains at least SRCDIR
>  VPATH += $(SRCDIR)
>
> +ifneq ($(CONFIG_RTE_MAJOR_ABI),)
> +ifneq ($(LIBABIVER),)
> +LIBABIVER := $(CONFIG_RTE_MAJOR_ABI)
> +endif
> +endif
> +
>  ifeq ($(CONFIG_RTE_BUILD_SHARED_LIB),y)
>  LIB := $(patsubst %.a,%.so.$(LIBABIVER),$(LIB))
>  ifeq ($(EXTLIB_BUILD),n)
> +ifeq ($(CONFIG_RTE_MAJOR_ABI),)
>  ifeq ($(CONFIG_RTE_NEXT_ABI),y)
>  LIB := $(LIB).1
>  endif
> +endif
>  CPU_LDFLAGS += --version-script=$(SRCDIR)/$(EXPORT_MAP)
>  endif
>  endif
> @@ -156,11 +164,7 @@ $(RTE_OUTPUT)/lib/$(LIB): $(LIB)
>         @[ -d $(RTE_OUTPUT)/lib ] || mkdir -p $(RTE_OUTPUT)/lib
>         $(Q)cp -f $(LIB) $(RTE_OUTPUT)/lib
>  ifeq ($(CONFIG_RTE_BUILD_SHARED_LIB),y)
> -ifeq ($(CONFIG_RTE_NEXT_ABI)$(EXTLIB_BUILD),yn)
> -       $(Q)ln -s -f $< $(basename $(basename $@))
> -else
> -       $(Q)ln -s -f $< $(basename $@)
> -endif
> +       $(Q)ln -s -f $< $(shell echo $@ | sed 's/\.so.*/.so/')
>  endif
>
>  #
> --
> 2.7.4
>

Reviewed-by: Jan Blunck <jblunck at infradead.org>
Tested-by: Jan Blunck <jblunck at infradead.org>