sign-file: Document dependency on OpenSSL devel libraries

The revised sign-file program is no longer a script that wraps the openssl
program, but now rather a program that makes use of OpenSSL's crypto
library.  This means that to build the sign-file program, the kernel build
process now has a dependency on the OpenSSL development packages in
addition to OpenSSL itself.

Document this in Kconfig and in module-signing.txt.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/init/Kconfig b/init/Kconfig
index 62b725653c36..5d1a703663ad 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1897,6 +1897,10 @@ config MODULE_SIG
           is simply appended to the module. For more information see
           Documentation/module-signing.txt.
 
+          Note that this option adds the OpenSSL development packages as a
+          kernel build dependency so that the signing tool can use its crypto
+          library.
+
           !!!WARNING!!!  If you enable this option, you MUST make sure that the
           module DOES NOT get stripped after being signed.  This includes the
           debuginfo strip done by some packagers (such as rpmbuild) and