tamago | https://github.com/usbarmory/tamago

Copyright (c) WithSecure Corporation
https://foundry.withsecure.com

Andrea Barisani
andrea.barisani@withsecure.com | andrea@inversepath.com

Andrej Rosano
andrej.rosano@withsecure.com | andrej@inversepath.com

TamaGo is a framework that enables compilation and execution of unencumbered Go applications on bare metal ARM/RISC-V System-on-Chip (SoC) components.

The mx6ullevk package provides support for the MCIMX6ULL-EVK development board.

For more information about TamaGo see its repository and project wiki.

For the underlying driver support for this board see package imx6ul.

The package API documentation can be found on pkg.go.dev.

Go applications are simply required to import, the relevant board package to ensure that hardware initialization and runtime support takes place:

import (
	_ "github.com/usbarmory/tamago/board/nxp/mx6ullevk"
)

Build the TamaGo compiler (or use the latest binary release):

wget https://github.com/usbarmory/tamago-go/archive/refs/tags/latest.zip
unzip latest.zip
cd tamago-go-latest/src && ./all.bash
cd ../bin && export TAMAGO=`pwd`/go

Go applications can be compiled as usual, using the compiler built in the previous step, but with the addition of the following flags/variables and ensuring that the required SoC and board packages are available in GOPATH:

GO_EXTLINK_ENABLED=0 CGO_ENABLED=0 GOOS=tamago GOARM=7 GOARCH=arm \
  ${TAMAGO} build -ldflags "-T 0x80010000 -E _rt0_arm_tamago -R 0x1000"

An example application, targeting the MCIMX6ULL-EVK platform, is available.

The example application provides reference usage and a Makefile target for automatic creation of an ELF as well as imx image for flashing.

Follow the SDP procedure using the built imx image.

Copy the built imx image to a microSD as follows:

sudo dd if=<path to imx file> of=/dev/sdX bs=1M conv=fsync

IMPORTANT: /dev/sdX must be replaced with your microSD device (not eventual microSD partitions), ensure that you are specifying the correct one. Errors in target specification will result in disk corruption.

Ensure the SW601 boot switches on the processor board are set to microSD boot mode:

The standard output can be accessed through the debug console found on micro USB connector J1901 and the following picocom configuration:

picocom -b 115200 -eb /dev/ttyUSB0 --imap lfcrlf

The application can be debugged with GDB over JTAG using openocd (version > 0.11.0) and the gdbinit debugging helper published here.

# start openocd daemon
openocd -f interface/ftdi/jtagkey.cfg -f target/imx6ul.cfg -c "adapter speed 1000"

# connect to the OpenOCD command line
telnet localhost 4444

# debug with GDB
arm-none-eabi-gdb -x gdbinit example

Hardware breakpoints can be set in the usual way:

hb ecdsa.Verify
continue

The target can be executed under emulation as follows:

qemu-system-arm \
	-machine mcimx6ul-evk -cpu cortex-a7 -m 512M \
	-nographic -monitor none -serial null -serial stdio -net none \
	-kernel example -semihosting

The emulated target can be debugged with GDB by adding the -S -s flags to the previous execution command, this will make qemu waiting for a GDB connection that can be launched as follows:

arm-none-eabi-gdb -ex "target remote 127.0.0.1:1234" example

Breakpoints can be set in the usual way:

b ecdsa.Verify
continue

tamago | https://github.com/usbarmory/tamago
Copyright (c) WithSecure Corporation

These source files are distributed under the BSD-style license found in the LICENSE file.

The TamaGo logo is adapted from the Go gopher designed by Renee French and licensed under the Creative Commons 3.0 Attributions license. Go Gopher vector illustration by Hugo Arganda.