v1 was here: https://lists.nongnu.org/archive/html/qemu-devel/2018-06/threads.html#07252
For v2: - Added documentation as suggested by Dan B. - Fixed a backwards test of creds->username which slipped into the previous version by accident because I was fiddling around with the code after I'd tested it but before posting it. This version actually works. Note also there is an nbdkit patch: https://www.redhat.com/archives/libguestfs/2018-June/thread.html#00121 nbdkit has an automated test that qemu TLS-PSK (NBD client) interoperates with nbdkit (NBD server), so we can be confident that the client functionality will receive continuous testing in future. Rich.