README: Document that tools and libraries should be upgraded together.

On some distributions it was possible to upgrade separate parts of elfutils
individually. That causes hard to debug issues since some tools (e.g. readelf)
and some libraries (e.g. libdw) depend on libelf internal data structures,
which could be different between versions (or when configured with different
flags). So explicitly document that they should always be upgraded together.

Signed-off-by: Mark Wielaard <mjw@redhat.com>

diff --git a/README b/README
index 33cac74f19dc1439640ccc1b741e5fda3e3f45f4..138717b3c94acb6bc1f8661f9ac103a4419c0b89 100644 (file)
--- a/README
+++ b/README
@@ -10,3 +10,10 @@ Fundamental design decision:
   users must match.  No third-party EBL module are supported or allowed.
   The only reason there are separate modules is to not have the code for
   all architectures in all the binaries.
+
+- although the public libraries (libasm, libdw) have a stable API and are
+  backwards ABI compatbile they, and the elfutils tools, do depend on each
+  others internals, and on internals of libelf to provide their interfaces.
+  So they should always be upgraded in lockstep when packaging the tools
+  and libraries separately. For one example of how to do that, see the
+  config/elfutils.spec.