From 53dd82a7ca24f1353d2eeaba0fc684ef4f8b558c Mon Sep 17 00:00:00 2001
From: Andreas Gustafsson <gson@gson.org>
Date: Thu, 8 Mar 2018 08:55:22 -0500
Subject: [PATCH] oslib-posix: check for posix_memalign in configure script

Check for the presence of posix_memalign() in the configure script,
not using "defined(_POSIX_C_SOURCE) && !defined(__sun__)". This
lets qemu use posix_memalign() on NetBSD versions that have it,
instead of falling back to valloc() which is wasteful when the
required alignment is smaller than a page.

Backports commit 9bc5a7193fb422ee53187601eba577ee5d195522 from qemu
---
 qemu/configure          | 15 +++++++++++++++
 qemu/util/oslib-posix.c |  2 +-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/qemu/configure b/qemu/configure
index 33e7c224..1b169131 100755
--- a/qemu/configure
+++ b/qemu/configure
@@ -1196,6 +1196,21 @@ if test "$sanitizers" = "yes" ; then
   fi
 fi
 
+##########################################
+# check if we have posix_memalign()
+
+posix_memalign=no
+cat > $TMPC << EOF
+#include <stdlib.h>
+int main(void) {
+    void *p;
+    return posix_memalign(&p, 8, 8);
+}
+EOF
+if compile_prog "" "" ; then
+    posix_memalign=yes
+fi
+
 ##########################################
 # End of CC checks
 # After here, no more $cc or $ld runs
diff --git a/qemu/util/oslib-posix.c b/qemu/util/oslib-posix.c
index c86c7ff4..762bcb31 100644
--- a/qemu/util/oslib-posix.c
+++ b/qemu/util/oslib-posix.c
@@ -84,7 +84,7 @@ void *qemu_try_memalign(size_t alignment, size_t size)
         alignment = sizeof(void*);
     }
 
-#if defined(_POSIX_C_SOURCE) && !defined(__sun__)
+#if defined(CONFIG_POSIX_MEMALIGN)
     int ret;
     ret = posix_memalign(&ptr, alignment, size);
     if (ret != 0) {