Adrian Cable

Alexis - this looks to be like a "normal" (non-LTS) board. I think your CPU temperature really is around 73 degrees, which sounds normal to me for 100% load on 4 cores.
 
For me, on the LTS board, in the same scenario, I get a reading around 40000 (i.e. 40 degrees C). Unless I've misunderstood, I think an offset is (at least roughly) enough.

You are (very genuinely) welcome!

Any more details so this is actionable by the community? Version/commit numbers of u-boot for working vs. non-working would be a great start on the way to a git bisect.

@Igor - I have just put a few thousands on your account. Can I therefore kindly a request a withdrawal of the "you don't care" part of the above? Thank you.

We have a commercial product running on Armbian based on the OPi Zero platform. We occasionally get reports from customers of intermittent connectivity, which (looking at the dmesg log on affected devices) manifests itself as something that looks very much like the up/down syndrome reported here. In this case we advise customers to purchase a cheap switch (e.g. https://www.amazon.com/NETGEAR-5-Port-Gigabit-Ethernet-Unmanaged/dp/B07S98YLHM/ref=sr_1_3?dchild=1&keywords=4+port+switch&qid=1614793487&sr=8-3) and put it between our product and their existing switch or router. We have found this always resolves the issue.
 
We still don't understand the cause, but at least we have a workaround (albeit not a perfect one).

Igor, sure, happy to suggest PR/changes. Can you tell me what user behaviour you are trying to guard against? I wasn't aware of any user-alterable parameters in htop that could cause it to crash. Thanks!

5kft - my bad about the overlay prefix. Checked on my build and you're right. I think I got confused previously because the DTB files for OPi Zero do indeed start with sun8i-h2-plus not sun8i-h3.
 
So here are the results from openssl speed -multi 4:
 
1. The CPU gets very hot indeed! See attached pic.
2. It doesn't crash.
3. It completes just fine, ending ...
Got: +F5:18:384:34.665335:0.028847 from 3
Got: +F5:19:384:35.294118:0.028333 from 3
Got: +F5:20:512:26.047904:0.038391 from 3
Got: +F5:21:512:27.372627:0.036533 from 3
Got: +F5:22:253:486.600000:0.002055 from 3
Got: +F5:23:448:105.500000:0.009479 from 3
Got: +F6:0:253:Ed25519:1240.400000:431.900000 from 3
Got: +F6:1:456:Ed448:198.400000:99.700000 from 3
OpenSSL 1.1.1d  10 Sep 2019
built on: Mon Apr 20 20:23:01 2020 UTC
options:bn(64,32) rc4(char) des(long) aes(partial) blowfish(ptr)
compiler: gcc -fPIC -pthread -Wa,--noexecstack -Wall -Wa,--noexecstack -g -O2 -fdebug-prefix-map=/build/openssl-8NbErV/openssl-1.1.1d=. -fstack-protector-strong -Wformat -Werror=format-security -DOPENSSL_USE_NODELETE -DOPENSSL_PIC -DOPENSSL_CPUID_OBJ -DOPENSSL_BN_ASM_MONT -DOPENSSL_BN_ASM_GF2m -DSHA1_ASM -DSHA256_ASM -DSHA512_ASM -DKECCAK1600_ASM -DAES_ASM -DBSAES_ASM -DGHASH_ASM -DECP_NISTZ256_ASM -DPOLY1305_ASM -DNDEBUG -Wdate-time -D_FORTIFY_SOURCE=2
 
So I vote to include 1.368GHz.
 
-Adrian

Werner - that's a great idea! In case you or others want to test as well, here are my corrected lines in the DTS for the OPi Zero:
 
 
                opp-1104000000 {
                        opp-hz = < 0x00 0x41cdb400 >;
                        opp-microvolt = < 0x13d620 0x13d620 0x13d620 >;
                        clock-latency-ns = < 0x3b9b0 >;
                };
                opp-1200000000 {
                        opp-hz = < 0x00 0x47868c00 >;
                        opp-microvolt = < 0x13d620 0x13d620 0x13d620 >;
                        clock-latency-ns = < 0x3b9b0 >;
                };
                opp-1296000000 {
                        opp-hz = < 0x00 0x4d3f6400 >;
                        opp-microvolt = < 0x13d620 0x13d620 0x13d620 >;
                        clock-latency-ns = < 0x3b9b0 >;
                };
                opp-1368000000 {
                        opp-hz = < 0x00 0x518a0600 >;
                        opp-microvolt = < 0x13d620 0x13d620 0x13d620 >;
                        clock-latency-ns = < 0x3b9b0 >;
                };
 
Running now at 1.368GHz and hasn't crashed. I'm going to try stress etc. and see what happens.
 
-Adrian