issue #82: added doc about DCAS support

[libcds.git] / readme.md

diff --git a/readme.md b/readme.md
index 54c6f15b6e71c596ce456e0dc75d492c7bd379b7..539796d5c6ce790a6fb94426d9cd711d0f9ee57d 100644 (file)
--- a/readme.md
+++ b/readme.md
@@ -46,6 +46,16 @@ Evolution of libcds (Gource visualization by Landon Wilkins): https://www.youtub
    - *nix: [use CMake](build/cmake/readme.md)\r
    - Windows: use MS Visual C++ 2015 project\r
 \r
+Some parts of libcds may depend on DCAS (double-width compare-and-swap) atomic primitive if\r
+the target architecture supports it. For x86, cmake build script enables `-mcx16` compiler flag that\r
+switches DCAS support on. You may manually disable DCAS support with the following command line flags\r
+in GCC/clang (for MS VC++ compiler DCAS is not supported):\r
+  - `-DCDS_DISABLE_128BIT_ATOMIC` - for 64bit build\r
+  - `-DCDS_DISABLE_64BIT_ATOMIC` - for 32bit build\r
+\r
+**All your projects AND libcds MUST be compiled with the same flags - either with DCAS support or without it.**\r
+   \r
+   \r
 **Pull request requirements**\r
 - Pull-request to *master* branch will be unconditionally rejected\r
 - *integration* branch is intended for pull-request. Usually, *integration* branch is the same as *master*\r