08.01.2019 15:11, Joachim Strömbergson пишет:
Aloha!
Hi,
Pavel: Did you perform the suggested test? Any result?
yes, unfortunately waiting (for up to an hour or so) didn't help. One
thing I've discovered is that if I run all the unit-tests with 60 MHz
and then switch FMC clock to 90 MHz without resetting the FPGA, the
first unit test (hal_get_random) passes, but further tests that need
random numbers lock up. I don't know the internals of the TRNG, it looks
like at 90 MHz entropy pool is not replenished or something like that.
Regards
JoachimS
On 2018-12-20 13:48, Joachim Strömbergson wrote:
Aloha!
First: Great work. That was one blizzard of commits.
On 2018-12-20 12:57, Pavel Shatov wrote:
Now the bad news. For some reason the new bitstream (`fpga show cores'
should report ECDSA version 0.20 instead of 0.11 now) fails
unit-tests.py. It locks up in hal_get_random() waiting for the valid bit
of CSPRNG core to go high. If I disable this test, it locks up a bit
further in 'test_attribute_bloat_token_big' which calls hal_uuid_gen()
which in its turn again calls hal_get_random(). If I drop FMC clock to
60 MHz (line 156 of stm-fmc.c sets the divisor: 2 is for 90 MHz, 3 is
for 60 MHz), then all the tests pass just fine. This is strange because
we've already seen this situation, but then we clearly had failed
timing, while now everything should be fine. I haven't done any thorough
investigation yet, my very preliminary guess is that maybe we need to
change the number of taps in the ring oscillator entropy source or
something like that. I do have a platform cable, so given hints on where
to look I can try to debug, but I suggest that someone first tries to
reproduce the situation, because maybe I'm doing something wrong (not
pulled latest changes from Joachim, etc...)
Strange.
Could you try and rerun the unit-tests a while later (as in minutes)
without resetting the FPGA. Basically run unit-tests, see that it hangs
and abort. Wait a while and run unit-tests later.
If it is the ROSC core not delivering values, and that the RNG hasn't
yet initalized the CSPRNG and isn't ready to deliver random values it
should get to that point eventually. There are timeouts for the mixer to
wait for entropy from the entropy providers. As long as the external
avalanche source is alive, the mixer will end up with enough entropy
words. It will just take a number of timeouts for each word that it
should get from the ROSC core.
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С уважением,
Шатов Павел
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