On a zEC12 or z13, a glibc with lock elision enabled infers from HWCAP
that the prerequisites for lock elision are met. Then it may use TBEGIN
and other transactional-execution instructions which are not implemented
by Valgrind. Likewise, the upcoming glibc 2.23 will exploit vector
instructions if they are advertised by HWCAP; and those are currently
not implemented by Valgrind either. In general, the increased use of
ifunc may lead to more such cases in the future.
This patch suppresses the advertising of those hardware features via
HWCAP which are either not known to Valgrind or currently unsupported.
Patch by Andreas Arnez (arnez@linux.vnet.ibm.com).
Fixes BZ #353680.
git-svn-id: svn://svn.valgrind.org/valgrind/trunk@15702 a5019735-40e9-0310-863c-91ae7b9d1cf9
diff --git a/README.s390 b/README.s390
index 5b3d3c0..96dac1b 100644
--- a/README.s390
+++ b/README.s390
@@ -22,6 +22,9 @@
- Some gcc versions use mvc to copy 4/8 byte values. This will affect
certain debug messages. For example, memcheck will complain about
4 one-byte reads/writes instead of just a single read/write.
+- The transactional-execution facility is not supported; it is masked
+ off from HWCAP.
+- The vector facility is not supported; it is masked off from HWCAP.
Hardware facilities