Libgcrypt makes use of certain hardware features. If the use of a feature is not desired it may be either be disabled by a program or globally using a configuration file. The currently supported features are
To disable a feature for all processes using Libgcrypt 1.6 or newer, create the file /etc/gcrypt/hwf.deny and put each feature not to be used on a single line. Empty lines, white space, and lines prefixed with a hash mark are ignored. The file should be world readable.
To disable a feature specifically for a program that program must tell
it Libgcrypt before before calling
gcry_control (GCRYCTL_DISABLE_HWF, "intel-rdrand", NULL);
To print the list of active features you may use this command:
mpicalc --print-config | grep ^hwflist: | tr : '\n' | tail -n +2
NB. Libgcrypt uses the RDRAND feature only as one source of entropy. A CPU with a broken RDRAND will thus not compromise of the random number generator