[PATCH v5 18/20] configure: Detect kcov support and introduce CONFIG_KCOV

[Aleksandar Markovic <aleksandar.markovic@rt-rk.com>]

From: Aleksandar Markovic <amarkovic@wavecomp.com>

kcov is kernel code coverage tracing tool. It requires kernel 4.4+
compiled with certain kernel options. Its interface consists of
three ioctls.

This patch checks if kcov support is present on build machine, and
stores the result in variable CONFIG_KCOV, meant to be used in
linux-user code related to the support for above mentioned ioctls.

Signed-off-by: Aleksandar Markovic <amarkovic@wavecomp.com>
---
 configure | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/configure b/configure
index 940bf9e..dbdba8f 100755
--- a/configure
+++ b/configure
@@ -4752,6 +4752,24 @@ if compile_prog "" "" ; then
   syncfs=yes
 fi
 
+# check for kcov support (kernel must be 4.4+, compiled with certain options)
+kcov=no
+cat > $TMPC << EOF
+#include <sys/kcov.h>
+
+int main(void)
+{
+    ioctl(-1, KCOV_ENABLE, NULL);
+    ioctl(-1, KCOV_DISABLE, NULL);
+    ioctl(-1, KCOV_INIT_TRACE, NULL);
+
+    return 0;
+}
+EOF
+if compile_prog "" "" ; then
+  kcov=yes
+fi
+
 # Check we have a new enough version of sphinx-build
 has_sphinx_build() {
     # This is a bit awkward but works: create a trivial document and
@@ -6874,6 +6892,9 @@ fi
 if test "$syncfs" = "yes" ; then
   echo "CONFIG_SYNCFS=y" >> $config_host_mak
 fi
+if test "$kcov" = "yes" ; then
+  echo "CONFIG_KCOV=y" >> $config_host_mak
+fi
 if test "$inotify" = "yes" ; then
   echo "CONFIG_INOTIFY=y" >> $config_host_mak
 fi
-- 
2.7.4