Brian Swetland @swetland@chaos.social

#introductions

Hi, I'm Brian. I hack on software and hardware.

I've been writing operating systems for a living for 20-odd years now: BeOS at Be, HiptopOS at Danger, Android at Android and then at Google, Fuchsia/Zircon at Google, LK here and there, various toy and experimental systems from time to time.

I grew up with the C64 in the early 80s and worry a lot about modern platforms being too closed and restrictive.

I am a fan of sci-fi and fantasy written, televised, animated, and gamed.

Ethernet PMODs back from JLCPCB with all the surface mount assembly done, 1 week after the job was sent. Just a matter of soldering down the magjacks and 2x6 headers and they're ready to go. First one already working with LiteEth MAC on an IceSugarPro FPGA board (Lattice ECP5).
#fpga #pcb #osdev

Ethernet PMODs continue through manufacturing... pcb fab is done... assembly in progress... and RJ45 magjacks and 0.1" headers arrived from digikey today.
#pcb #fpga #pmod #ethernet

PCB production chugs along. I love the little embedded videos of the process steps that JLCPCB has in their progress report popups.
#fpga #pmod #pcb

I continue to be amazed how painless this is! Uploaded gerbers and BOM and placement files to JLCPCB, got a quote for 10 boards (fab and assembly, all the SMT parts) for $60, shipping $20, coupon for $9 off, pushed button and off it all goes...
#fpga #pmod #pcb

Alrighty, this Ethernet PMOD is starting to look like it might be almost ready to fab... #fpga #pmod #ethernet

Here's the source code that this is helping explain...
A very, very simplistic "kernel" illustrating MMU setup, starting a userspace thread, handling syscalls...
https://github.com/swetland/os-workshop/blob/main/example/ex25-kernel.c
#osdev #riscv

Attempting to illustrate how the RISCV Sv32 MMU works in a simple demonstration program.
#riscv #osdev #diagrams

Happiness is discovering that while Mouser and Digikey still have NOT A SINGLE 10/100M Ethernet PHY available, Microchip has ~17500 LAN8720As ready to ship directly. Soon they shall have 25 fewer on hand!
#fpga #pcb #ethernet

Slowly assembling what I hope are some reasonably useful slides on RISCV RV32IM and OS internals.
#osdev #riscv #slides #drawio

Video capture of Qemu running a bare metal RISCV RV32IM preemptive multitasking demo.
#osdev #riscv #qemu