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[ovs-dev,RFC,1/2] libopenvswitch: Rename to libfoo-X.Y.

Message ID 20170426230803.13527-2-joe@ovn.org
State Accepted
Headers show

Commit Message

Joe Stringer April 26, 2017, 11:08 p.m. UTC
The current intent for Open vSwitch is to maintain libopenvswitch ABI
stability for minor versions, for example each release within the 2.7.z
series. According to the following documentation, no changes to exported
headers should be made.

http://docs.openvswitch.org/en/latest/internals/contributing/libopenvswitch-abi/

However, it is occasionally necessary to make changes to
{include/openvswitch,lib}/*.h headers to fix issues within a given
release series. The current libtool tagging mechanism in the build
system does not allow for this without creating a conflict between the
libtool 'current' version and the next minor release of OVS.

This patch modifies libopenvswitch build to include the MAJOR.MINOR
release version in the libX name, and include the libtool CURRENT and
OVS MICRO release in the libtool versioning tags to indicate library
stability. The resulting format is "libfoo-X.Y.so.CURRENT.0.Z" for OVS
release "X.Y.Z".

Developers should still attempt to avoid introducing ABI-breaking changes
within a particular OVS-X.Y release series, but if this is not possible
this patch introduced a mechanism to allow an ABI-breaking fix to be
introduced. In such a case, developers may update the libtool CURRENT
version to indicate this breakage to library users.

Signed-off-by: Joe Stringer <joe@ovn.org>
---
 .../internals/contributing/libopenvswitch-abi.rst        | 16 +++++++++-------
 m4/openvswitch.m4                                        |  6 +++---
 2 files changed, 12 insertions(+), 10 deletions(-)
diff mbox

Patch

diff --git a/Documentation/internals/contributing/libopenvswitch-abi.rst b/Documentation/internals/contributing/libopenvswitch-abi.rst
index 845d90898859..8fa24db964cd 100644
--- a/Documentation/internals/contributing/libopenvswitch-abi.rst
+++ b/Documentation/internals/contributing/libopenvswitch-abi.rst
@@ -87,16 +87,18 @@  ABI Policy
 ----------
 
 Open vSwitch will export the ABI version at the time of release, such that the
-library name will be the major version, and the rest of the release version
-information will be conveyed with a libtool interface version.
+library name will be the major.minor version, and the rest of the release
+version information will be conveyed with a libtool interface version.
 
 The intent is for Open vSwitch to maintain an ABI stability for each minor
 revision only (so that Open vSwitch release 2.5 carries a guarantee for all
-2.5.ZZ micro-releases).  This means that any porting effort to stable branches
-must take not to disrupt the existing ABI.  Each new 'minor-level' release
-bumps the libtool 'current' version, which informs the linker of a backwards
-incompatible interface, signaling that libraries exposed by Open vSwitch 2.6
-will not maintain ABI stability with Open vSwitch 2.5.
+2.5.ZZ micro-releases). This means that any porting effort to stable branches
+must take not to disrupt the existing ABI.
+
+In the event that a bug must be fixed in a backwards-incompatible way,
+developers must bump the libtool 'current' version to inform the linker of the
+ABI breakage. This will signal that libraries exposed by the subsequent release
+will not maintain ABI stability with the previous version.
 
 Coding
 -------
diff --git a/m4/openvswitch.m4 b/m4/openvswitch.m4
index 48892f9f720e..648750ab5ad9 100644
--- a/m4/openvswitch.m4
+++ b/m4/openvswitch.m4
@@ -614,9 +614,9 @@  AC_DEFUN([OVS_LIBTOOL_VERSIONS],
   OVS_MAJOR=`echo "$PACKAGE_VERSION" | sed -e 's/[[.]].*//'`
   OVS_MINOR=`echo "$PACKAGE_VERSION" | sed -e "s/^$OVS_MAJOR//" -e 's/^.//' -e 's/[[.]].*//'`
   OVS_MICRO=`echo "$PACKAGE_VERSION" | sed -e "s/^$OVS_MAJOR.$OVS_MINOR//" -e 's/^.//' -e 's/[[^0-9]].*//'`
-  OVS_LT_RELINFO="-release $OVS_MAJOR"
-  OVS_LT_VERINFO="-version-info $OVS_MINOR:$OVS_MICRO"
+  OVS_LT_RELINFO="-release $OVS_MAJOR.$OVS_MINOR"
+  OVS_LT_VERINFO="-version-info $LT_CURRENT:$OVS_MICRO"
   OVS_LTINFO="$OVS_LT_RELINFO $OVS_LT_VERINFO"
-  AC_MSG_RESULT([libX-$OVS_MAJOR.so.$OVS_MINOR.0.$OVS_MICRO)])
+  AC_MSG_RESULT([libX-$OVS_MAJOR.$OVS_MINOR.so.$LT_CURRENT.0.$OVS_MICRO)])
   AC_SUBST(OVS_LTINFO)
     ])