[openssl] openssl-3.0 update

[beldmit at gmail.com]

The branch openssl-3.0 has been updated
       via  0c9afd6918dfe5e818b3545ede88011adeb6e76b (commit)
      from  09e1818a54cad2d348138427234660fcabae793e (commit)


- Log -----------------------------------------------------------------
commit 0c9afd6918dfe5e818b3545ede88011adeb6e76b
Author: Dmitry Belyavskiy <beldmit at gmail.com>
Date:   Tue Nov 23 15:18:52 2021 +0100

    More detailed explanation how do engines work in 3.0
    
    Related: #16868, #17081, #17107
    
    Reviewed-by: Paul Dale <pauli at openssl.org>
    (Merged from https://github.com/openssl/openssl/pull/17115)
    
    (cherry picked from commit 29a27cb2c5c1757831f42117871f8c59058343a9)

-----------------------------------------------------------------------

Summary of changes:
 doc/man7/migration_guide.pod | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/doc/man7/migration_guide.pod b/doc/man7/migration_guide.pod
index 627173f180..67e102fa4c 100644
--- a/doc/man7/migration_guide.pod
+++ b/doc/man7/migration_guide.pod
@@ -121,6 +121,21 @@ FIPS module, as detailed below. Authors and maintainers of external engines are
 strongly encouraged to refactor their code transforming engines into providers
 using the new Provider API and avoiding deprecated methods.
 
+=head3 Support of legacy engines
+
+If openssl is not built without engine support or deprecated API support, engines
+will still work. However, their applicability will be limited.
+
+New algorithms provided via engines will still work.
+
+Engine-backed keys can be loaded via custom B<OSSL_STORE> implementation.
+In this case the B<EVP_PKEY> objects created via L<ENGINE_load_private_key(3)>
+will be concidered legacy and will continue to work.
+
+To ensure the future compatibility, the engines should be turned to providers.
+To prefer the provider-based hardware offload, you can specify the default
+properties to prefer your provider.
+
 =head3 Versioning Scheme
 
 The OpenSSL versioning scheme has changed with the OpenSSL 3.0 release. The new