trOS is a small, zig and assembly, aarch64 RPI3 bare metal OS thingy.

some stuff that works:

• mailbox calls
• uart0
• framebuffer (initializing/clearing/printing characters and strings)
• gpio
• mmio

stuff that is being worked on:

• SD card support (read/write)
• USB
• networking
• anything else not mentioned above

all you need to build is zig itself. grab it and run:

zig build

the output file will be in zig-cache. alternatively, you can run the following to launch qemu (will auto-detect windows or unix):

zig build qemu

you can have qemu redirect to a pty as well:

zig build qemu -Dpty

you can start a gdb remote server:

zig build qemu -Dgdb

you can combine the last two:

zig build qemu -Dpty -Dgdb

if you want a very small binary:

zig build -Drelease-fast
# or
zig build -Drelease-small

both of these produce a binary that is about ~5kb.

if you want release optimizations while still having safety checks:

zig build -Drelease-safe

and thats about all the build options. note that you can combine all -D options with the qemu directive, e.g.:

zig build qemu -Drelease-small

will build a release-small binary and then run it with qemu.

if you use the 4coder editor, there is an included project file you can use to open the source as well as build/run it. the file assumes you have zig in your PATH. note the the 'run' functionality is a bit lacking because the pane it opens does not accept input, though this should be less of an inssue when USB support is available.

thanks to andrew kelly for the build file.

thanks to bzt for the emmc/sd card code.