Fix: x86 and s390 uatomic: __hp() macro warning with gcc 11

[urcu.git] / README.md

diff --git a/README.md b/README.md
index 2f088fe4d6f12d58affc05eef7c7f8cc2b7da85d..02b903a2e18ea9d533cc4cd31e0b6288a32cc3b6 100644 (file)
--- a/README.md
+++ b/README.md
@@ -91,6 +91,9 @@ supported, with the following exceptions:
 
 Clang version 3.0 (based on LLVM 3.0) is supported.
 
+Glibc >= 2.4 should work but the older version we test against is
+currently 2.17.
+
 For developers using the Git tree:
 
 This source tree is based on the autotools suite from GNU to simplify
@@ -430,6 +433,33 @@ In addition to the usual `make check` target, Userspace RCU features
   - `make bench`: long (many hours) benchmarks.
 
 
+Known issues
+------------
+
+There is an application vs library compatibility issue between
+applications built using Userspace RCU 0.10 headers linked against
+Userspace RCU 0.11 or 0.12 shared objects. The problem occurs as
+follows:
+
+  - An application executable is built with _LGPL_SOURCE defined, includes
+    any of the Userspace RCU 0.10 urcu flavor headers, and is built
+    without the -fpic compiler option.
+
+  - The Userspace RCU 0.10 library shared objects are updated to 0.11
+    or 0.12 without rebuilding the application.
+
+  - The application will hang, typically when RCU grace period
+    (synchronize_rcu) is invoked.
+
+Some possible work-arounds for this are:
+
+  - Rebuild the application against Userspace RCU 0.11+.
+
+  - Rebuild the application with -fpic.
+
+  - Upgrade Userspace RCU to 0.13+ without installing 0.11 nor 0.12.
+
+
 Contacts
 --------