Make compatfd fallback more robust

Be more friendly when signalfd() fails, and also add configure checks to detect
that syscall(SYS_signalfd) actually works.  malc pointed out that some installs
do not have /usr/include/linux headers that are in sync with the glibc headers
so why SYS_signalfd is defined, it's #defined to _NR_signalfd which is not
defined in the /usr/include/linux header.

While this is a distro bug, it doesn't hurt to do a more thorough job in
detection.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>



git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5334 c046a42c-6fe2-441c-8c8c-71466251a162

1 files changed, 35 insertions, 0 deletions

diff --git a/configure b/configure
index 6a727c0a5a..5030558a45 100755
--- a/configure
+++ b/configure
@@ -110,6 +110,8 @@ curses="yes"
 aio="yes"
 nptl="yes"
 mixemu="no"
+signalfd="no"
+eventfd="no"
 
 # OS specific
 targetos=`uname -s`
@@ -901,6 +903,33 @@ EOF
   fi
 fi
 
+##########################################
+# signalfd probe
+cat > $TMPC << EOF
+#define _GNU_SOURCE
+#include <unistd.h>
+#include <sys/syscall.h>
+#include <signal.h>
+int main(void) { return syscall(SYS_signalfd, -1, NULL, _NSIG / 8); }
+EOF
+
+if $cc $ARCH_CFLAGS -o $TMPE $TMPC 2> /dev/null ; then
+  signalfd=yes
+fi
+
+##########################################
+# eventfd probe
+cat > $TMPC << EOF
+#define _GNU_SOURCE
+#include <unistd.h>
+#include <sys/syscall.h>
+int main(void) { return syscall(SYS_eventfd, 0); }
+EOF
+
+if $cc $ARCH_CFLAGS -o $TMPE $TMPC 2> /dev/null ; then
+  eventfd=yes
+fi
+
 # Check if tools are available to build documentation.
 if [ -x "`which texi2html 2>/dev/null`" ] && \
    [ -x "`which pod2man 2>/dev/null`" ]; then
@@ -1229,6 +1258,12 @@ if test "$aio" = "yes" ; then
   echo "#define CONFIG_AIO 1" >> $config_h
   echo "CONFIG_AIO=yes" >> $config_mak
 fi
+if test "$signalfd" = "yes" ; then
+  echo "#define CONFIG_signalfd 1" >> $config_h
+fi
+if test "$eventfd" = "yes" ; then
+  echo "#define CONFIG_eventfd 1" >> $config_h
+fi
 
 # XXX: suppress that
 if [ "$bsd" = "yes" ] ; then