Disable jitter entropy source by default

Almost all modern CPUs have a hardware randomness source in some form.
Most of virtual machines have /dev/hwrng provided by a virtual host.
The jitter entropy source is just eating CPU cycles in such cases, so
disable it by default. It can be enabled explicitly for the older
hardware without hardware entropy (like the Athlon FX CPU).

Resolves: RHEL-91113

Signed-off-by: Vladis Dronov <vdronov@redhat.com>

rng-tools.spec

@@ -12,7 +12,7 @@
 Summary:        Random number generator related utilities
 Name:           rng-tools
 Version:        6.17
-Release:        4%{?dist}
+Release:        5%{?dist}
 License:        GPL-2.0-or-later
 URL:            https://github.com/nhorman/rng-tools
 Source0:        %{url}/archive/v%{version}/%{name}-%{version}.tar.gz
@@ -104,6 +104,9 @@ install -D %{SOURCE2} -m0644 %{buildroot}%{_sysconfdir}/sysconfig/rngd
 %config(noreplace) %attr(0644,root,root)    %{_sysconfdir}/sysconfig/rngd
 
 %changelog
+* Thu Jun 26 2025 Vladis Dronov <vdronov@redhat.com> - 6.17-5
+- Disable jitter entropy source by default (RHEL-91113)
+
 * Tue Oct 29 2024 Troy Dawson <tdawson@redhat.com> - 6.17-4
 - Bump release for October 2024 mass rebuild:
   Resolves: RHEL-64018

rngd.sysconfig

@@ -1,3 +1,3 @@
 # Optional arguments passed to rngd. See rngd(8) and
 # https://bugzilla.redhat.com/show_bug.cgi?id=1252175#c21
-RNGD_ARGS="--fill-watermark=0 -x pkcs11 -x nist -x qrypt -x namedpipe -D daemon:daemon"
+RNGD_ARGS="--fill-watermark=0 -x pkcs11 -x nist -x qrypt -x namedpipe -x jitter -D daemon:daemon"