From: Daniel Arndt <daniel.arndt@iwr.uni-heidelberg.de>
Date: Mon, 13 May 2019 17:53:23 +0000 (+0200)
Subject: Warn about using CUDA+Threads+march=native
X-Git-Tag: v9.1.0-rc1~21^2~1
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=87a40a9aea2512722f70d3cbf8a4dea5f00e7952;p=dealii.git

Warn about using CUDA+Threads+march=native
---

diff --git a/doc/external-libs/cuda.html b/doc/external-libs/cuda.html
index 68222e1d31..fda03f4c9b 100644
--- a/doc/external-libs/cuda.html
+++ b/doc/external-libs/cuda.html
@@ -72,5 +72,19 @@
       will lead to segmentation faults in MPI calls.
     </p>
 
+    <p>
+      Using CUDA in combination with architecture-specific C++ compiler flags
+      like <code>-march=native</code> is known to be fragile and there might be
+      compatibility issues with other libraries, e.g. using CUDA 10.1 with
+      <code>-DDEAL_II_WITH_THREADS=ON</code> and
+      <code>-DDEAL_II_CXX_FLAGS=-march=native</code> results in compile time
+      errors like:
+      <pre>
+
+        /usr/lib/gcc/x86_64-linux-gnu/7/include/avx512fintrin.h(11265): error: identifier "__builtin_ia32_scalefsd_round" is undefined
+        /usr/lib/gcc/x86_64-linux-gnu/7/include/avx512fintrin.h(11274): error: identifier "__builtin_ia32_scalefss_round" is undefined
+      </pre>
+    </p>
+
   </body>
 </html>