trace: Add ftrace tracing backend

This patch adds a ftrace tracing backend which sends trace event to
ftrace marker file. You can effectively compare qemu trace data and
kernel(especially, kvm.ko when using KVM) trace data.
The ftrace backend is restricted to Linux only.

To try out the ftrace backend:

 $ ./configure --trace-backend=ftrace
 $ make

if you use KVM, enable kvm events in ftrace:

 # sudo echo 1 > /sys/kernel/debug/tracing/events/kvm/enable

After running qemu by root user, you can get the trace:

 # cat /sys/kernel/debug/tracing/trace

Signed-off-by: Eiichi Tsukata <eiichi.tsukata.xh@hitachi.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/configure b/configure
index c4d85ba51d..e818e8b357 100755
--- a/configure
+++ b/configure
@@ -4004,6 +4004,14 @@ if test "$trace_backend" = "dtrace"; then
     echo "CONFIG_TRACE_SYSTEMTAP=y" >> $config_host_mak
   fi
 fi
+if test "$trace_backend" = "ftrace"; then
+  if test "$linux" = "yes" ; then
+    echo "CONFIG_TRACE_FTRACE=y" >> $config_host_mak
+    trace_default=no
+  else
+    feature_not_found "ftrace(trace backend)"
+  fi
+fi
 echo "CONFIG_TRACE_FILE=$trace_file" >> $config_host_mak
 if test "$trace_default" = "yes"; then
   echo "CONFIG_TRACE_DEFAULT=y" >> $config_host_mak