WIP: for feedback from tinygo folks

[iansmith]

@aykevl @jaddr2line

This PR is to confirm that I have the files setup "right" to be a good citizen in tinygo.

The test program (note this does UART synchronously, not yet to the point of interrupts):

package main

import "machine"

var testMyBSS int

func main() {
	// set up serial console
	machine.UARTInit()

	// say hello
	machine.UARTPuts("Hello World!\n")

	// echo everything back
	for {
		machine.UARTPutc(machine.UARTGetc())
	}
}

If you want to test locally:

$ tinygo build -target rpi3 -o uart main.go
$ llvm-objcopy -O binary uart kernel8.img

Assuming you have Qemu 4.2 you can run with:

$ qemu-system-aarch64 -M raspi3 -kernel kernel8.img -serial null -serial stdio

[aykevl]

Note: I have changed the PR from master to dev, as that's what we're working on (and dev has many changes now not included in master).

[aykevl]

There are a number of conflicts, which you can fix by rebasing on top of the dev branch (although it appears like you already did some of that in #1048?)

[iansmith]

@aykevl It appears that the problem with picolib is affecting circle-ci as well. Check the errors in this build. This is the same trouble I had on my mac.

https://app.circleci.com/pipelines/github/iansmith/tinygo/10/workflows/2e5badf7-1a2e-4297-a333-62dc856cd707/jobs/61

[iansmith]

@aykevl @jaddr2line

I implemented all the suggestions from Ayke on overriding and machine generation of the hardware MMIO registers.

Close the other PRs that were confusing the issue.