x/build: add LUCI linux-riscv64 builder

[mengzhuo]

Following the instructions at Dashboard builders:

hostname linux-riscv64-mengzhuo

CSR is linux-riscv64-mengzhuo.csr.txt since Github doesn't seem to allow attaching with the name linux-riscv64-mengzhuo.csr origin issue asked for.

[gopherbot]

Change https://go.dev/cl/534976 mentions this issue: main.star: add openbsd-ppc64, linux-riscv64, freebsd-riscv64 builders

[dmitshur]

Thanks. Here's the resulting certificate: linux-riscv64-mengzhuo-1697128389.cert.txt.

I've mailed CLs to define your new builder in LUCI and will comment once that's done.

[dmitshur]

Step 3 is complete (CL 534976 is submitted), so you should be able to proceed with the next steps. Please feel free to comment here if you see something unexpected, or run into a problem that the documentation doesn't cover. Thanks.

[mengzhuo]

@dmitshur I've setup the builder, however I don't know how to debug with log https://chromium-swarm.appspot.com/task?id=655ba20db7351610

Any tips?

[dmitshur]

BOT_DIED sounds like the bot running on your builder crashed, although it did run for 4m 13s. Is there anything useful in logs on your side? I'm not spotting much on the LUCI end so far.

CC @cagedmantis if you have a chance to look this week.

[cagedmantis]

@mengzhuo I think the logs on https://chromium-swarm.appspot.com/bot?e=true&id=linux-riscv64-mengzhuo might be helpful. Try selecting the events tab.