The Zither Go Runtime Backend

The Zither Go runtime backend is responsible for generating the go.git sources defining the language's support on Fuchsia, derived from the FIDL syscall specifications of library zx.

Output layout

There are two sets of go.git sources generated:

• Private syscall bindings, for the runtime package:
  • src/runtime/vdso_keys_fuchsia.go
  • src/runtime/vdsocalls_fuchsia_${ARCH}.s
• Public syscall bindings defined as jumps to the runtime ones:
  • src/syscall/zx/syscalls_fuchsia.go
  • src/syscall/zx/syscalls_fuchsia_${ARCH}.s

This organization is due to the fact that the runtime package needs to make use of Fuchsia's syscalls, but the latter are usually expected to be defined in syscall, while syscall/zx depends on runtime.

GN integration

${fidl_target}_zither.go_runtime generates the set of sources, but this set is only meant to be accessed in GN - via zither_golden_files() - for testing. To properly generate sources for go.git, zither is expected to be invoked directly.

Bindings

Any declaration type not mentioned below is ignored.

Syscalls

Each syscall declaration yields one private FFI binding in the runtime package, vdsoCall_zx_foo_bar(), and one public one in syscall/zx, Sys_foo_bar().