Getting Started Guide

Quick Start

This guide assumes the following simple layout where your workspace (for example mylk) is a sibling of the cloned lk repository and the fetched toolchains live under a toolchain directory in the same parent folder:

~/lk-work/ lk/ # cloned littlekernel repository toolchain/ # fetched toolchains (created by scripts/fetch-toolchains.py) mylk/ # example user workspace (created below)

  1. Create a work directory and clone lk
mkdir -p ~/lk-work && cd ~/lk-work
git clone https://github.com/littlekernel/lk
  1. Download an appropriate toolchain (this will create a toolchain/ directory under lk-work/lk/)
# Fetches the latest riscv64-elf toolchain for your host.
cd lk
scripts/fetch-toolchains.py --prefix riscv64-elf
  1. Add the toolchain bin directory to your PATH. Replace the example below with the actual toolchain folder you have downloaded.
export PATH=~/lk-work/lk/toolchain/riscv64-elf-15.1.0-Linux-x86_64/bin:$PATH
  1. Find available projects
ls project/*
  1. For example pick qemu-virt-riscv64-test and build the kernel
make qemu-virt-riscv64-test
  1. Test the kernel with Qemu using the provided script
scripts/do-qemuriscv -6S

Build A Hello App

Continue from Quick Start's steps above. Create your workspace as a sibling of the cloned lk repository and enter it (note the cd .. to move to the parent of lk):

cd ..   # make sure you're in the parent directory that contains the cloned `lk`
mkdir -p mylk/{project,app} && cd mylk
  1. Configure your main makefile; set your toolchain path and point LKROOT to the cloned lk repository. Replace the PATH example with the actual toolchain path on your system.
cat << 'EOF' > makefile
export PATH := /path/to/your/toolchain/bin:$(PATH)  # e.g. ~/lk-work/toolchain/riscv64-elf-14.2.0-Linux-x86_64/bin
-include lk_inc.mk
LOCAL_DIR := .
LKMAKEROOT := .
LKROOT := ../lk
LKINC := $(LOCAL_DIR)
DEFAULT_PROJECT ?= myqr
BUILDROOT ?= $(LOCAL_DIR)

ifeq ($(filter $(LKROOT),$(LKINC)), )
LKINC := $(LKROOT) $(LKINC)
endif

ifneq ($(LKROOT),.)
LKINC += $(LKROOT)/external
else
LKINC += external
endif

export LKMAKEROOT
export LKROOT
export LKINC
export BUILDROOT
export DEFAULT_PROJECT
export TOOLCHAIN_PREFIX
_top:
    @$(MAKE) -C $(LKMAKEROOT) -rR -f $(LKROOT)/engine.mk $(addprefix -I,$(LKINC)) $(MAKECMDGOALS)
$(MAKECMDGOALS): _top
    @:
.PHONY: _top
EOF
  1. Copy an existing project as your new project
cp ../lk/project/qemu-virt-riscv64-test.mk project/project1.mk
  1. Create a new hello app under the app directory
mkdir app/hello

cat << 'EOF' > app/hello/hello.c
#include <stdio.h>
#include <string.h>
#include <malloc.h>
#include <app.h>
#include <platform.h>
#include <lk/console_cmd.h>

static int hello(int argc, const console_cmd_args *argv) {
    printf("hello world\n");
    return 0;
}

STATIC_COMMAND_START
STATIC_COMMAND("hello", "hello tests", &hello)
STATIC_COMMAND_END(hello);

APP_START(hello)
APP_END
EOF

cat << 'EOF' > app/hello/rules.mk
LOCAL_DIR := $(GET_LOCAL_DIR)

MODULE := $(LOCAL_DIR)

MODULE_SRCS += $(LOCAL_DIR)/hello.c

include make/module.mk
EOF
  1. Add the following line to your project's makefile (project/project1.mk) so the project builds your app as well:
MODULES += app/hello
  1. Check your directory structure
# mylk
tree
.
├── app
│   └── hello
│       ├── hello.c
│       └── rules.mk
├── makefile
└── project
        └── project1.mk

# lk-work
tree ../ -d -L 1
../.
├── lk
└── mylk
  1. Build your project
make project1
  1. Run your kernel with Qemu
qemu-system-riscv64 -machine virt -cpu rv64 -m 48 -smp 1 -bios none -nographic -kernel build-project1/lk.elf

You will see output similar to:

FDT: found memory arena, base 0x80000000 size 0x3000000
FDT: found 1 cpus

welcome to lk/MP

boot args 0x0 0x1020 0x0 0x0
INIT: cpu 0, calling hook 0x8001e3b8 (version) at level 0x3ffff, flags 0x1
version:
	arch:     riscv
	platform: qemu-virt-riscv
	target:   qemu-virt-riscv
	project:  project1
	buildid:  L96DH_LOCAL
initializing heap
calling constructors
initializing mp
initializing threads
initializing timers
initializing ports
creating bootstrap completion thread
top of bootstrap2()
INIT: cpu 0, calling hook 0x8001a848 (minip) at level 0x70000, flags 0x1
INIT: cpu 0, calling hook 0x8001b6c6 (pktbuf) at level 0x70000, flags 0x1
pktbuf: creating 256 pktbuf entries of size 1536 (total 393216)
INIT: cpu 0, calling hook 0x8001fe08 (virtio) at level 0x70000, flags 0x1
RISCV: percpu cpu num 0x0 hart id 0x0
RISCV: Machine mode
RISCV: mvendorid 0x0 marchid 0x0 mimpid 0x0 mhartid 0x0
RISCV: misa 0x800000000014112d
RISCV: Releasing 0 secondary harts from purgatory
initializing platform
PCIE: initializing pcie with ecam at 0x30000000 found in FDT
PCI: pci ecam functions installed
PCI: last pci bus is 255
PCI dump:
    bus 0
     dev 0000:00:00.0 vid:pid 1b36:0008 base:sub:intr 6:0:0
PCI dump post assign:
    bus 0
     dev 0000:00:00.0 vid:pid 1b36:0008 base:sub:intr 6:0:0
initializing target
initializing apps
starting app inetsrv
starting internet servers
starting app shell
entering main console loop
  1. Test your hello application
] hello
hello world