Am Dienstag, 10. November 2020, 10:37:02 CET schrieb Paul Menzel: Hi Paul, > Dear Stephan, > > > Thank you for the quick reply. > > Am 10.11.20 um 10:25 schrieb Stephan Mueller: > > Am Montag, 9. November 2020, 20:31:02 CET schrieb Paul Menzel: > >> By mistake I built `XFRM_ESP` into the Linux kernel, resulting in > >> > >> CONFIG_CRYPTO_SEQIV=y > >> CONFIG_CRYPTO_ECHAINIV=y > >> > >> and also the Jitterentropy RNG to be built in. > >> > >> CRYPTO_JITTERENTROPY=y > >> > >> So, on the Asus F2A85-M PRO starting Linux 4.10-rc3 with > >> `initcall_debug`, the init method is run unconditionally, and it takes > >> 17.5 ms, which is over ten percent of the overall 900 ms the Linux > > > > Hm, 17.5 / 900 = 2%, or am I missing something? > > Indeed, that is embarrassing. My bad. > > >> kernel needs until loading the init process. > >> > >> [ 0.300544] calling jent_mod_init+0x0/0x2c @ 1 > >> [ 0.318438] initcall jent_mod_init+0x0/0x2c returned 0 after > >> 17471 usecs > >> > >> Looking at the output of systemd-bootchart, it looks like, that this > >> indeed delayed the boot a little, as the other init methods seem to be > >> ordered after it. > >> > >> I am now building it as a module, but am wondering if the time can be > >> reduced to below ten milliseconds. > > > > What you see is the test whether the Jitter RNG has a proper noise source. > > The function jent_entropy_init() is the cause of the operation. It > > performs 1024 times a test to validate the appropriateness of the noise > > source. You can adjust that with the TESTLOOPCOUNT in this function. But > > I am not sure adjusting is a wise course of action. > > Out of curiosity, why 1024 and not, for example, 128 or 2048? Is there > some statistics behind it? See [1] section 4.3 bullet 4 is the culprit. The startup test includes the referenced test logic. [1] https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-90B.pdf > > > Kind regards, > > Paul Ciao Stephan
