[PATCH] Documentation: note that KCOV is supported since gcc 4.5

[Dmitry Vyukov]

Now that we have gcc plugins and in particular sancov plugin,
KCOV can be used with gcc 4.5+. Note this in the docs.

I've tested CONFIG_KCOV with gcc 4.8.4 (stock for ubuntu 14.04)
and it works. It even emits very comparable number of coverage
callbacks: 420153 vs 422211 for gcc 7.0.

Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxx>
Cc: Vegard Nossum <vegard.nossum@xxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: linux-doc@xxxxxxxxxxxxxxx
Cc: syzkaller@xxxxxxxxxxxxxxxx
Signed-off-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
---
 Documentation/dev-tools/kcov.rst | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/Documentation/dev-tools/kcov.rst b/Documentation/dev-tools/kcov.rst
index 2c41b71..50d515a 100644
--- a/Documentation/dev-tools/kcov.rst
+++ b/Documentation/dev-tools/kcov.rst
@@ -19,7 +19,9 @@ Configure the kernel with::
 
         CONFIG_KCOV=y
 
-CONFIG_KCOV requires gcc built on revision 231296 or later.
+CONFIG_KCOV is natively supported by gcc 6.0+ (revision 231296) via
+-fsanitize-coverage=trace-pc flag. gcc 4.5+ supports CONFIG_KCOV with plugins
+(see Documentation/gcc-plugins.txt and CONFIG_GCC_PLUGIN_SANCOV).
 Profiling data will only become accessible once debugfs has been mounted::
 
         mount -t debugfs none /sys/kernel/debug
-- 
2.8.0.rc3.226.g39d4020