Flashing it

Find the card first: diskutil list on macOS, lsblk on Linux. Get this wrong and you will overwrite something else. Read the size and confirm it is the card.

1. Check the image and write it. On Linux the device is /dev/sdX or /dev/mmcblkN and the flag is bs=4M. For the card from CI, the image is nullroute.img in the folder you downloaded.

$ cd out/release
$ shasum -a 256 -c SHA256SUMS
$ diskutil unmountDisk /dev/diskN          # macOS
$ sudo dd if=nullroute-0.1.0.img of=/dev/rdiskN bs=4m status=progress

2. Read back exactly as many bytes as the image holds, and compare the hash with the image's line in SHA256SUMS before you boot it. A whole number of 4 MB blocks would not do: the image is not a multiple of 4 MB, so the extra bytes would change the hash.

$ sudo head -c "$(stat -f %z nullroute-0.1.0.img)" /dev/rdiskN | shasum -a 256    # macOS
$ sudo head -c "$(stat -c %s nullroute-0.1.0.img)" /dev/sdX | sha256sum            # Linux

That is provisioning tier 0. See the tiers.