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Re: [PATCH v3 3/3] tests/qtest: Introduce tests for AMD/Xilinx Versal TR
From: |
Peter Maydell |
Subject: |
Re: [PATCH v3 3/3] tests/qtest: Introduce tests for AMD/Xilinx Versal TRNG device |
Date: |
Tue, 17 Oct 2023 14:47:25 +0100 |
On Wed, 4 Oct 2023 at 15:27, Tong Ho <tong.ho@amd.com> wrote:
>
> Signed-off-by: Tong Ho <tong.ho@amd.com>
> ---
> tests/qtest/meson.build | 2 +-
> tests/qtest/xlnx-versal-trng-test.c | 490 ++++++++++++++++++++++++++++
> 2 files changed, 491 insertions(+), 1 deletion(-)
> create mode 100644 tests/qtest/xlnx-versal-trng-test.c
>
> +static void trng_test_autogen(void)
> +{
> + const size_t cnt = 512 / 32;
> + uint32_t rng[cnt], prng[cnt];
> + size_t n;
> +
> + trng_reset();
> +
> + /* PRNG run #1 */
> + trng_reseed(prng_seed);
> + trng_generate(true);
> +
> + n = trng_collect(prng, cnt);
> + if (n != cnt) {
> + FAILED("PRNG_1 Auto-gen test failed: expected = %u, got = %u",
> + (unsigned)cnt, (unsigned)n);
> + }
> +
> + /* TRNG, should not match PRNG */
> + trng_reseed(NULL);
> + trng_generate(true);
> +
> + n = trng_collect(rng, cnt);
> + if (n != cnt) {
> + FAILED("TRNG Auto-gen test failed: expected = %u, got = %u",
> + (unsigned)cnt, (unsigned)n);
> + }
> +
> + if (!memcmp(rng, prng, sizeof(rng))) {
> + FAILED("TRNG test failed: matching PRNG");
> + }
Why can't the TRNG output ever match the PRNG output ?
It's random numbers, so you might get (un)lucky.
This sort of check results in flaky CI, because very very
occasionally the RNG will give you output that results in
a test failure.
> +
> + /* PRNG #2: should matches run #1 */
> + trng_reseed(prng_seed);
> + trng_generate(true);
> +
> + n = trng_collect(rng, cnt);
> + if (n != cnt) {
> + FAILED("PRNG_2 Auto-gen test failed: expected = %u, got = %u",
> + (unsigned)cnt, (unsigned)n);
> + }
> +
> + if (memcmp(rng, prng, sizeof(rng))) {
> + FAILED("PRNG_2 Auto-gen test failed: does not match PRNG_1");
> + }
> +}
> +
thanks
-- PMM