Setup

How the platform works, independent of any one board or site: how the hosts boot, how the network is laid out, what runs on each host, and how the web application reaches the boards.

Both sites are built the same way. One x86 gateway serves the boot chain and the web tier, a managed PoE switch carries both the network and the power, and each FPGA host hangs off one switch port with one FPGA board attached:

                        ┌────────────────────────────────────┐
      browser ──https──▶│ gateway             nginx + Django │
                        │ (one per site)  dnsmasq DHCP/TFTP, │
                        │                 NFS root, ssh hop  │
                        └──────────────────┬─────────────────┘
                                           │ eth-local
                        ┌──────────────────┴─────────────────┐
                        │ PoE switch      one VLAN per port  │
                        │                 PoE off/on by SNMP │
                        └───┬──────────────┬──────────────┬──┘
                            │              │              │
                     ┌──────┴─────┐ ┌──────┴─────┐ ┌──────┴─────┐
                     │ Pi host    │ │ Pi host    │ │ Pi host  … │
                     │ netboots   │ │            │ │            │
                     │ read-only  │ │            │ │            │
                     │ NFS root + │ │            │ │            │
                     │ tmpfs      │ │            │ │            │
                     │ camera,    │ │            │ │            │
                     │ fpgas-tt   │ │            │ │            │
                     └──────┬─────┘ └──────┬─────┘ └──────┬─────┘
                            │              │              │  USB / JTAG / PCIe
                     ┌──────┴─────┐ ┌──────┴─────┐ ┌──────┴─────┐
                     │ FPGA board │ │ FPGA board │ │ FPGA board │
                     └────────────┘ └────────────┘ └────────────┘

boot path: Pi ─DHCP▶ dnsmasq ─TFTP▶ kernel ─NFS▶ shared read-only root
user path: browser ─https▶ gateway ─ssh/proxy▶ Pi ─USB/JTAG/PCIe▶ board
prov path: CI ─build▶ root image ─pull▶ gateway ─▶ NFS root, before any Pi boots

One VLAN per port is the Welland scheme, and the gateway link is a VLAN trunk only there; PS1 is one flat network with a MAC table. fpgas-tt runs only on the Tiny Tapeout hosts, and only some hosts carry a camera. The pages below take that picture apart:

• Netboot and the NFS root — how a Pi with no SD card and no local storage gets a kernel and a root filesystem, and what it costs you that the root is shared.

• Network and power — how a Pi gets its address and its power, and why the two sites lay that out differently.

• Bootloader EEPROM, by machine: a Raspberry Pi 5 (check it, upgrade a locked one) and a Compute Module in a Compute Blade (does it need anything). What was measured and what is not known is behind both.

• What runs on a Pi host — the packages, systemd units and boot-time settings that building the root leaves behind on every host.

• Orange Pi H3 hosts — how seven non-Raspberry boards boot the same NFS root after being loaded with U-Boot over USB FEL, and what to do when one of them does not come back.

• The gateway host — what the one x86 machine per site runs, how it is deployed, and what a rebuild from bare metal has to get right.

• What a site needs from its upstream network — the forwards, routes and DNS records the network above the gateway must provide, behind a NAT gateway or on a public address.

• Accounts and logins at welland — who can log in to the gateway and to the Pis, with which keys, and why the Pis keep a password.

• The web application — what a visitor sees, which Django apps serve it, and how the site role puts it on the gateway.

• The Tiny Tapeout stack — the fpgas-tt daemon, the board catalogue, the demo bitstreams and the Commander fork behind tinytapeout.fpgas.online.

• Verifying a deployment — what to change when adding another device of a type the fleet already has, and how to prove it works.