From 701daa5298b3befe2aff05ce590533165abb9ba4 Mon Sep 17 00:00:00 2001
From: Rafael Folco <rfolco@br.ibm.com>
Date: Mon, 10 Apr 2017 12:39:38 +0000
Subject: [PATCH] Port CPU_SPINWAIT to __powerpc64__

Hyper-threaded CPUs may need a special instruction inside spin loops in
order to yield to another virtual CPU. The 'pause' instruction that is
available for x86 is not supported on Power.
Apparently the extended mnemonics like yield, mdoio, and mdoom are not
actually implemented on POWER8, although mentioned in the ISA 2.07
document. The recommended magic bits are an 'or 31,31,31'.
---
 configure.ac | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index 37745c40..894e72d0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -398,8 +398,9 @@ case "${host_cpu}" in
 	    fi
 	fi
 	;;
-  powerpc)
+  powerpc*)
 	AC_DEFINE_UNQUOTED([HAVE_ALTIVEC], [ ])
+	CPU_SPINWAIT='__asm__ volatile("or 31,31,31")'
 	;;
   *)
 	;;