security_flags: Add comment about what it does and who uses it

It was pointed out that people couldn't easily see who used this or
why so add some comments about that.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

diff --git a/meta/conf/distro/include/security_flags.inc b/meta/conf/distro/include/security_flags.inc
index 0ee38140efb5a7c81d55cb10405afb33ee83b1e5..9608c7f06914157df9eddccb2da454e71db60234 100644 (file)
--- a/meta/conf/distro/include/security_flags.inc
+++ b/meta/conf/distro/include/security_flags.inc
@@ -1,3 +1,10 @@
+# Setup extra CFLAGS and LDFLAGS which have 'security' benefits. These 
+# don't work universally, there are recipes which can't use one, the other
+# or both so a blacklist is maintained here. The idea would be over
+# time to reduce this list to nothing.
+# From a Yocto Project perspective, this file is included and tested
+# in the DISTRO="poky-lsb" configuration.
+
 SECURITY_CFLAGS ?= "-fstack-protector-all -pie -fpie -D_FORTIFY_SOURCE=2"
 SECURITY_NO_PIE_CFLAGS ?= "-fstack-protector-all -D_FORTIFY_SOURCE=2"
 SECURITY_LDFLAGS ?= "-Wl,-z,relro,-z,now"