Re: warning: TEST_RANDOM_GENERATOR


Paul Sokolovsky
 

Hello Andrei,

On Tue, 29 Jan 2019 13:35:19 +0000
"Andrei Gansari" <andrei.gansari@nxp.com> wrote:

Hello everyone,

I have a question regarding TEST_RANDOM_GENERATOR.
When building networking samples for boards with entropy devices is
get the warning: warning: TEST_RANDOM_GENERATOR (defined at
subsys/random/Kconfig:8) was assigned the value 'y' but got the value
'n'.

We find in subsys/random/Kconfig
TEST_RANDOM_GENERATOR depends on !ENTROPY_HAS_DRIVER
ENTROPY_DEVICE_RANDOM_GENERATOR depends on ENTROPY_HAS_DRIVER

Most networking samples have set TEST_RANDOM_GENERATOR=y and as I
understand it's for pseudo-random number generation. Boards that have
entropy devices (ENTROPY_HAS_DRIVER) will disable
TEST_RANDOM_GENERATOR.

When setting TEST_RANDOM_GENERATOR we just want a random generator or
we want a predictable/intuitive random number generator?
We want to have a "random generator" device be present in Zephyr
setup, which various subsystems then can use (instead of failing). So,
TEST_RANDOM_GENERATOR is a fallback choice which is always available.
For example, it's available in qemu_* boards, which otherwise don't
have a "real" randomgen. That's why you see TEST_RANDOM_GENERATOR in
many networking samples - the only way to make networking samples
accessing to *anyone* is to make sure they run with qemu networking.

Regarding "predictable random number generator", that's interesting
idea for some kinds of testing, but I'm personally not aware of us
using such advanced and cunning test methods in Zephyr.

If we want
both type of generators, then we could remove ENTROPY_HAS_DRIVER
check on TEST_RANDOM_GENERATOR?

Is this an issue?


Andrei G.
[]

--
Best Regards,
Paul

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