The randomness tests in the NPCM7xx RNG test fail intermittently
but fairly frequently. On my machine running the test in a loop:
while QTEST_QEMU_BINARY=./qemu-system-aarch64 ./tests/qtest/npcm7xx_rng-test; do true; done
will fail in less than a minute with an error like:
ERROR:../../tests/qtest/npcm7xx_rng-test.c:256:test_first_byte_runs:
assertion failed (calc_runs_p(buf.l, sizeof(buf) * BITS_PER_BYTE) > 0.01): (0.00286205989 > 0.01)
(Failures have been observed on all 4 of the randomness tests,
not just first_byte_runs.)
It's not clear why these tests are failing like this, but intermittent
failures make CI and merge testing awkward, so disable running them
unless a developer specifically sets QEMU_TEST_FLAKY_RNG_TESTS when
running the test suite, until we work out the cause.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20201102152454.8287-1-peter.maydell@linaro.org
Reviewed-by: Havard Skinnemoen <hskinnemoen@google.com>
The RNG module returns a byte of randomness when the Data Valid bit is
set.
This implementation ignores the prescaler setting, and loads a new value
into RNGD every time RNGCS is read while the RNG is enabled and random
data is available.
A qtest featuring some simple randomness tests is included.
Reviewed-by: Tyrone Ting <kfting@nuvoton.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Havard Skinnemoen <hskinnemoen@google.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
