README.md · 中午不睡下午不醒/Linux Lab

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# Table of Content

- [1. Linux Lab Overview](#1-linux-lab-overview)
    - [1.1 Project Introduction](#11-project-introduction)
    - [1.2 Project Homepage](#12-project-homepage)
    - [1.3 Demonstration](#13-demonstration)
       - [1.3.1 Basic Operations](#131-basic-operations)
       - [1.3.2 Cool Operations](#132-cool-operations)
    - [1.4 Project Functions](#14-project-functions)
    - [1.5 Project History](#15-project-history)
       - [1.5.1 Project Origins](#151-project-origins)
       - [1.5.2 Problems Solved](#152-problems-solved)
       - [1.5.3 Project Born](#153-project-born)
- [2. Linux Lab Installation](#2-linux-lab-installation)
    - [2.1 Hardware and Software Requirement](#21-hardware-and-software-requirement)
    - [2.2 Docker Installation](#22-docker-installation)
    - [2.3 Choose a working directory](#23-choose-a-working-directory)
    - [2.4 Switch to normal user](#24-switch-to-normal-user)
    - [2.5 Download the lab](#25-download-the-lab)
    - [2.6 Run and login the lab](#26-run-and-login-the-lab)
    - [2.7 Update and rerun the lab](#27-update-and-rerun-the-lab)
    - [2.8 Quickstart: Boot a board](#28-quickstart-boot-a-board)
- [3. Linux Lab Kickstart](#3-linux-lab-kickstart)
    - [3.1 Using boards](#31-using-boards)
       - [3.1.1 List available boards](#311-list-available-boards)
       - [3.1.2 Choosing a board](#312-choosing-a-board)
       - [3.1.3 Using as plugins](#313-using-as-plugins)
       - [3.1.4 Configure boards](#314-configure-boards)
    - [3.2 Build in one command](#32-build-in-one-command)
    - [3.3 Detailed Operations](#33-detailed-operations)
       - [3.3.1 Downloading](#331-downloading)
       - [3.3.2 Checking out](#332-checking-out)
       - [3.3.3 Patching](#333-patching)
       - [3.3.4 Configuration](#334-configuration)
          - [3.3.4.1 Default Configuration](#3341-default-configuration)
          - [3.3.4.2 Manual Configuration](#3342-manual-configuration)
          - [3.3.4.3 Old default configuration](#3343-old-default-configuration)
       - [3.3.5 Building](#335-building)
       - [3.3.6 Saving](#336-saving)
       - [3.3.7 Booting](#337-booting)
- [4. Linux Lab Advance](#4-linux-lab-advance)
    - [4.1 Using Linux Kernel](#41-using-linux-kernel)
       - [4.1.1 non-interactive configuration](#411-non-interactive-configuration)
       - [4.1.2 using kernel modules](#412-using-kernel-modules)
       - [4.1.3 using kernel features](#413-using-kernel-features)
       - [4.1.3 Create new development branch](#413-create-new-development-branch)
    - [4.2 Using Uboot Bootloader](#42-using-uboot-bootloader)
    - [4.3 Using Qemu Emulator](#43-using-qemu-emulator)
    - [4.4 Using Toolchains](#44-using-toolchains)
    - [4.5 Using Rootfs](#45-using-rootfs)
    - [4.6 Debugging Linux and Uboot](#46-debugging-linux-and-uboot)
       - [4.6.1 Debugging Linux](#461-debugging-linux)
       - [4.6.2 Debugging Uboot](#462-debugging-uboot)
    - [4.7 Test Automation](#47-test-automation)
    - [4.8 File Sharing](#48-file-sharing)
       - [4.8.1 Install files to rootfs](#481-install-files-to-rootfs)
       - [4.8.2 Share with NFS](#482-share-with-nfs)
       - [4.8.3 Transfer via tftp](#483-transfer-via-tftp)
       - [4.8.4 Share with 9p virtio](#484-share-with-9p-virtio)
    - [4.9 Learning Assembly](#49-learning-assembly)
    - [4.10 Learning C](#410-learning-c)
       - [4.10.1 Host build and Run](#4101-host-build-and-run)
       - [4.10.2 Cross build and Run](#4102-cross-build-and-run)
    - [4.11 Running any make goals](#411-running-any-make-goals)
    - [4.12 More Usage](#412-more-usage)
- [5. Linux Lab Development](#5-linux-lab-development)
    - [5.1 Choose a board supported by qemu](#51-choose-a-board-supported-by-qemu)
    - [5.2 Create the board directory](#52-create-the-board-directory)
    - [5.3 Clone a Makefile from an existing board](#53-clone-a-makefile-from-an-existing-board)
    - [5.4 Configure the variables from scratch](#54-configure-the-variables-from-scratch)
    - [5.5 At the same time, prepare the configs](#55-at-the-same-time,-prepare-the-configs)
    - [5.6 Choose the versions of kernel, rootfs and uboot](#56-choose-the-versions-of-kernel,-rootfs-and-uboot)
    - [5.7 Configure, build and boot them](#57-configure,-build-and-boot-them)
    - [5.8 Save the images and configs](#58-save-the-images-and-configs)
    - [5.9 Upload everything](#59-upload-everything)
- [6. FAQs](#6-faqs)
    - [6.1 Docker Issues](#61-docker-issues)
       - [6.1.1 Speed up docker images downloading](#611-speed-up-docker-images-downloading)
       - [6.1.2 Docker network conflicts with LAN](#612-docker-network-conflicts-with-lan)
       - [6.1.3 Why not allow running Linux Lab in local host](#613-why-not-allow-running-linux-lab-in-local-host)
       - [6.1.4 Run tools without sudo](#614-run-tools-without-sudo)
       - [6.1.5 Network not work](#615-network-not-work)
       - [6.1.6 Client.Timeout exceeded while waiting headers](#616-clienttimeout-exceeded-while-waiting-headers)
       - [6.1.7 Restart Linux Lab after host system shutdown or reboot](#617-restart-linux-lab-after-host-system-shutdown-or-reboot)
    - [6.2 Qemu Issues](#62-qemu-issues)
       - [6.2.1 Why kvm speedding up is disabled](#621-why-kvm-speedding-up-is-disabled)
       - [6.2.2 Poweroff hang](#622-poweroff-hang)
       - [6.2.3 How to exit qemu](#623-how-to-exit-qemu)
       - [6.2.4 Boot with missing sdl2 libraries failure](#624-boot-with-missing-sdl2-libraries-failure)
    - [6.3 Environment Issues](#63-environment-issues)
       - [6.3.1 NFS/tftpboot not work](#631-nfstftpboot-not-work)
       - [6.3.2 How to switch windows in vim](#632-how-to-switch-windows-in-vim)
       - [6.3.3 How to delete typo in shell command line](#633-how-to-delete-typo-in-shell-command-line)
       - [6.3.4 Language input switch shortcuts](#634-language-input-switch-shortcuts)
       - [6.3.5 How to tune the screen size](#635-how-to-tune-the-screen-size)
       - [6.3.6 How to work in fullscreen mode](#636-how-to-work-in-fullscreen-mode)
       - [6.3.7 How to record video](#637-how-to-record-video)
       - [6.3.8 Linux Lab not response](#638-linux-lab-not-response)
       - [6.3.9 VNC login with failures](#639-vnc-login-with-failures)
       - [6.3.10 Ubuntu Snap Issues](#6310-ubuntu-snap-issues)
       - [6.3.11 How to exit fullscreen mode of vnc clients](#6311-how-to-exit-fullscreen-mode-of-vnc-clients)
    - [6.4 Lab Issues](#64-lab-issues)
       - [6.4.1 No working init found](#641-no-working-init-found)
       - [6.4.2 linux/compiler-gcc7.h: No such file or directory](#642-linuxcompiler-gcc7h-no-such-file-or-directory)
       - [6.4.3 linux-lab/configs: Permission denied](#643-linux-labconfigs-permission-denied)
       - [6.4.4 scripts/Makefile.headersinst: Missing UAPI file](#644-scriptsmakefileheadersinst-missing-uapi-file)
       - [6.4.5 unable to create file: net/netfilter/xt_dscp.c](#645-unable-to-create-file-netnetfilterxt_dscpc)
       - [6.4.6 how to run as root](#646-how-to-run-as-root)
       - [6.4.7 not in supported list](#647-not-in-supported-list)
- [7. Contact and Sponsor](#7-contact-and-sponsor)

# 1. Linux Lab Overview

## 1.1 Project Introduction

This project aims to create a Qemu-based Linux development Lab to easier the learning, development and testing of [Linux Kernel](http://www.kernel.org).

Linux Lab is open source with no warranty – use at your own risk.

[![Docker Qemu Linux Lab](doc/images/linux-lab.jpg)](http://showdesk.io/2017-03-11-14-16-15-linux-lab-usage-00-01-02/)

## 1.2 Project Homepage

* Homepage
    * <http://tinylab.org/linux-lab/>

* Repository
    * <https://gitee.com/tinylab/linux-lab>
    * <https://github.com/tinyclub/linux-lab>

Related Projects:

* Cloud Lab
    * Linux Lab Running Environment Manager
    * <http://tinylab.org/cloud-lab>

* Linux 0.11 Lab
    * Learning Linux 0.11
    * Download it to `labs/linux-0.11-lab` and use it in Linux Lab directly
    * <http://tinylab.org/linux-0.11-lab>

* CS630 Qemu Lab
    * Learning X86 Linux Assembly
    * Download it to `labs/cs630-qemu-lab` and use it in Linux Lab directly
    * <http://tinylab.org/cs630-qemu-lab>

## 1.3 Demonstration

### 1.3.1 Basic Operations

* [Basic Usage](http://showdesk.io/7977891c1d24e38dffbea1b8550ffbb8)
  * [Learning Uboot](http://showterm.io/11f5ae44b211b56a5d267)
  * [Learning Assembly](http://showterm.io/0f0c2a6e754702a429269)
  * [Boot ARM Ubuntu 18.04 on Vexpress-a9 board](http://showterm.io/c351abb6b1967859b7061)
  * [Boot Linux v5.1 on ARM64/Virt board](http://showterm.io/9275515b44d208d9559aa)
  * [Boot Riscv32/virt and Riscv64/virt boards](http://showterm.io/37ce75e5f067be2cc017f)

### 1.3.2 Cool Operations

* [One command of testing a specified kernel feature](http://showterm.io/7edd2e51e291eeca59018)
  * [One command of testing multiple specified kernel modules](http://showterm.io/26b78172aa926a316668d)
  * [Batch boot testing of all boards](http://showterm.io/8cd2babf19e0e4f90897e)
  * [Batch testing the debug function of all boards](http://showterm.io/0255c6a8b7d16dc116cbe)

## 1.4 Project Functions

Now, Linux Lab becomes an intergrated Linux learning, development and testing environment, it supports:

| Items    | Description
|----------|-----------------------------------------------------------------------
|Boards    | Qemu based, 8+ main Architectures, 15+ popular boards
|Components| Uboot, Linux / Modules, Buildroot, Qemu, Linux v2.6.10 ~ 5.x supported
|Prebuilt  | All of above components has been prebuilt
|Rootfs    | Support include initrd, harddisk, mmc and nfs, Debian availab for ARM
|Docker    | Cross toolchains available in one command, external ones configurable
|Acess     | Access via web browsers, available everywhere via web vnc or web ssh
|Network   | Builtin bridge networking, every board has network (except Raspi3)
|Boot      | Support serial port, curses (bash/ssh friendly) and graphic booting
|Testing   | Support automatic testing via `make test` target
|Debugging | debuggable via `make debug` target

Continue reading for more features and usage.

## 1.5 Project History

### 1.5.1 Project Origins

About 9 years ago, a tinylinux proposal: [Work on Tiny Linux Kernel](https://elinux.org/Work_on_Tiny_Linux_Kernel) accepted by embedded
linux foundation, therefore I have worked on this project for serveral months.

### 1.5.2 Problems Solved

During the project cycle, several scripts written to verify if the adding tiny features (e.g. [gc-sections](https://lwn.net/images/conf/rtlws-2011/proc/Yong.pdf))
breaks the other kernel features on the main cpu architectures.

These scripts uses qemu-system-ARCH as the cpu/board simulator, basic boot+function tests have been done for ftrace+perf, accordingly, defconfigs,
rootfs, test scripts have been prepared, at that time, all of them were simply put in a directory, without a design or holistic consideration.

### 1.5.3 Project Born

They have slept in my harddisk for several years without any attention, untill one day, docker and novnc came to my world, at first, [Linux 0.11 Lab](http://gitee.com/tinylab/linux-0.11-lab) was born, after that, Linux Lab was designed to unify all of the above scripts, defconfigs, rootfs and test scripts.

# 2. Linux Lab Installation

## 2.1 Hardware and Software Requirement

Linux Lab is a full embedded Linux development system, it needs enough calculation capacity and disk & memory storage space, to avoid potential extension issues, here is the recommended configuration:

| Hardware     | Requirement      | Description                                          |
|--------------|------------------|------------------------------------------------------|
| Processor    | X86_64, > 1.5GHz | Must choose 64bit X86 while using virtual machine    |
| Disk         | >= 50G           | System (25G), Docker Images(~5G), Linux Lab (20G)    |
| Memory       | >= 4G            | Lower than 4G may have many unpredictable exceptions |

If often use, please increase disk storage to 100G~200G and memory storage to 8G.

And here is a list for verified operating systems for references:

| OS         | System Version      | Docker Version | Kernel Version
|------------|---------------------|----------------|-----------------------------
| Ubuntu     | 16.04, 18.04, 20.04 | 18.09.4        | Linux 4.15, 5.0, 5.3, 5.4
| Debian     | bullseye            | 19.03.7        | Linux 5.4.42
| Arch Linux |                     | 19.03.11       | Linux 5.4.50, 5.7.4
| CentOS     | 7.6, 7.7            | 19.03.8        | Linux 3.10, 5.2.9
| Deepin     | 15.11               | 18.09.6        | Linux 4.15
| Mac OS X   | 10.15.5             | 19.03.8        | Darwin 19.5.0
| Windows    | 10 PRO, WSL2        | 19.03.8        | MINGW64_NT-10.0-17134
| Manjaro    |                     | 19.03.11       | Linux 5.8.3

Welcome to take a look at [the systems running Linux Lab](https://github.com/tinyclub/linux-lab/issues/5) and share yours, for example:

$ tools/docker/env.sh
    System: Ubuntu 16.04.6 LTS
    Linux: 4.4.0-176-generic
    Docker: Docker version 18.09.4, build d14af54

## 2.2 Docker Installation

Docker is required by Linux Lab, please install it at first:

- Linux, Mac OSX, Windows 10

[Docker CE](https://store.docker.com/search?type=edition&offering=community)

- older Windows (include some older Windows 10)

Install Ubuntu via Virtualbox or Vmware Virtual Machine

Before running Linux Lab, please refer to section 6.1.4 and make sure the following command works without sudo and without any issue:

$ docker run hello-world

In China, to use docker service normally, please **must** configure one of chinese docker mirror sites, for example:

* [Aliyun Docker Mirror Documentation](https://help.aliyun.com/document_detail/60750.html)
    * For non Univerisity users, require login with freely registered account

* [USTC Docker Mirror Documentation](https://lug.ustc.edu.cn/wiki/mirrors/help/docker)
    * For Univerisity users

More docker related issues, such as download slowly, download timeout and download errors, are cleary documented in the 6.1 section of FAQs.

The other issues, please read the [official docker docs](https://docs.docker.com).

**Notes for Ubuntu Users**
  - doc/install/ubuntu-docker.md

**Notes for Arch Users**
  - doc/install/arch-docker.md

**Notes for Manjaro Users**
  - doc/install/manjaro-docker.md

**Notes for Windows Users**:

- Please make sure your Windows version support docker: [Official Docker Documentation](https://docs.docker.com)

- Linux Lab only tested with 'Git Bash' in Windows, please must use with it
      - After installing [Git For Windows](https://git-scm.com/downloads), "Git Bash Here" will come out in right-button press menu

## 2.3 Choose a working directory

If installed via Docker Toolbox, please enter into the `/mnt/sda1` directory of the `default` system on Virtualbox, otherwise, after poweroff, the data will be lost for the default `/root` directory is only mounted in DRAM.

$ cd /mnt/sda1

For Linux, please simply choose one directory in `~/Downloads` or `~/Documents`.

$ cd ~/Documents

For Windows and Mac OSX, to compile Linux normally, please enable or create a case sensitive filesystem as the working space at first:

**Windows**:

$ cd /path/to/cloud-lab
    $ fsutil file SetCaseSensitiveInfo ./ enable

**Mac OSX**:

$ hdiutil create -type SPARSE -size 60g -fs "Case-sensitive Journaled HFS+" -volname labspace labspace.dmg
    $ hdiutil attach -mountpoint ~/Documents/labspace -nobrowse labspace.dmg.sparseimage
    $ cd ~/Documents/labspace

**Notes**: Docker Images, Linux and Buildroot source code require many storage space, please reserve at least 50G for them.

## 2.4 Switch to normal user

Before downloading Linux Lab, please **MUST** switch to normal user.

Check who am i, `0` means root, non-zero means normal user:

$ id -u `whoami`
    1000

If current user is `root`, switch to a normal one:

# id -u `whoami`
    0
    # sudo -su <USER>

If no normal user exists, create new:

$ sudo useradd --create-home --shell /bin/bash --user-group --groups adm,sudo laber
    $ sudo passwd laber
    $ sudo -su laber
    $ whoami
    laber

## 2.5 Download the lab

Use Ubuntu system as an example:

Download cloud lab framework, pull images and checkout linux-lab repository:

$ git clone https://gitee.com/tinylab/cloud-lab.git
    $ cd cloud-lab/ && tools/docker/choose linux-lab

If cloned source code with `root` account, please **MUST** switch to normal user and change their owner:

$ sudo -su <USER>
    $ sudo chown -R <USER>:<USER> -R cloud-lab/{*,.git}

## 2.6 Run and login the lab

Launch the lab and login with the user and password printed in the console:

$ tools/docker/run linux-lab

$ tools/docker/bash

Re-login the lab via web browser:

$ tools/docker/webvnc

The other login methods:

$ tools/docker/vnc
    $ tools/docker/ssh
    $ tools/docker/webssh

Choose one of the method:

$ tools/docker/login list  # List, choose and record
    $ tools/docker/login vnc   # Choose one directly and record for late login

Summary of login methods:

|   Login Method |   Description      |  Default User    |  Where               |
|----------------|--------------------|------------------|----------------------|
|   bash         | docker bash        |  ubuntu          | localhost            |
|   ssh          | normal ssh         |  ubuntu          | localhost            |
|   vnc          | normal vnc         |  ubuntu          | localhost+VNC client |
|   webvnc       | web desktop        |  ubuntu          | anywhere via internet|
|   webssh       | web ssh            |  ubuntu          | anywhere via internet|

Since vnc clients differs from operating systems, we use webvnc by default to make sure auto login vnc for all systems.

If really want to use local vnc clients, please install a vnc client, for example: `vinagre`, then specify it like this:

$ tools/docker/vnc vinagre

If the above command not work normally, based on the information printed above, please configure the vnc client yourself.

## 2.7 Update and rerun the lab

If want a newer version, we **must** back up any local changes at first, for example, save the container:

$ tools/docker/commit linux-lab
    $ git checkout -- configs/linux-lab/docker/name

And then update everything:

$ tools/docker/update linux-lab

If fails, please try to clean up the containers:

$ tools/docker/rm-all

Or even clean up the whole environments:

$ tools/docker/clean-all

Then rerurn linux lab:

$ tools/docker/rerun linux-lab

## 2.8 Quickstart: Boot a board

Get into the lab environment, switch directory:

$ cd /labs/linux-lab

Issue the following command to boot the prebuilt kernel and rootfs on the default `vexpress-a9` board:

$ make boot

Welcome to Linux Lab

linux-lab login: root

# uname -a
    Linux linux-lab 5.1.0 #3 SMP Thu May 30 08:44:37 UTC 2019 armv7l GNU/Linux
    #
    # poweroff
    #

Shutdown the board with the `poweroff` command. If some boards not support `poweroff`, please press `CTRL+a x`. Of course, open another terminal and issue kill or pkill command also can quit qemu.

# 3. Linux Lab Kickstart

## 3.1 Using boards

### 3.1.1 List available boards

List builtin boards:

$ make list
    [ aarch64/raspi3 ]:
          ARCH     = arm64
          CPU     ?= cortex-a53
          LINUX   ?= v5.1
          ROOTDEV_LIST := /dev/mmcblk0 /dev/ram0
          ROOTDEV ?= /dev/mmcblk0
    [ aarch64/virt ]:
          ARCH     = arm64
          CPU     ?= cortex-a57
          LINUX   ?= v5.1
          ROOTDEV_LIST := /dev/sda /dev/vda /dev/ram0 /dev/nfs
          ROOTDEV ?= /dev/vda
    [ arm/mcimx6ul-evk ]:
          ARCH     = arm
          CPU     ?= cortex-a9
          LINUX   ?= v5.4
          ROOTDEV_LIST := /dev/mmcblk0 /dev/ram0 /dev/nfs
          ROOTDEV ?= /dev/mmcblk0
    [ arm/versatilepb ]:
          ARCH     = arm
          CPU     ?= arm926t
          LINUX   ?= v5.1
          ROOTDEV_LIST := /dev/sda /dev/ram0 /dev/nfs
          ROOTDEV ?= /dev/ram0
    [ arm/vexpress-a9 ]:
          ARCH     = arm
          CPU     ?= cortex-a9
          LINUX   ?= v5.1
          ROOTDEV_LIST := /dev/mmcblk0 /dev/ram0 /dev/nfs
          ROOTDEV ?= /dev/ram0
    [ i386/pc ]:
          ARCH     = x86
          CPU     ?= qemu32
          LINUX   ?= v5.1
          ROOTDEV_LIST ?= /dev/hda /dev/ram0 /dev/nfs
          ROOTDEV_LIST[LINUX_v2.6.34.9] ?= /dev/sda /dev/ram0 /dev/nfs
          ROOTDEV ?= /dev/hda
    [ mips64el/ls2k ]:
          ARCH     = mips
          CPU     ?= mips64r2
          LINUX   ?= loongnix-release-1903
          LINUX[LINUX_loongnix-release-1903] := 04b98684
          ROOTDEV_LIST := /dev/sda /dev/ram0 /dev/nfs
          ROOTDEV ?= /dev/ram0
    [ mips64el/ls3a7a ]:
          ARCH     = mips
          CPU     ?= mips64r2
          LINUX   ?= loongnix-release-1903
          LINUX[LINUX_loongnix-release-1903] := 04b98684
          ROOTDEV_LIST ?= /dev/sda /dev/ram0 /dev/nfs
          ROOTDEV ?= /dev/ram0
    [ mipsel/ls1b ]:
          ARCH     = mips
          CPU     ?= mips32r2
          LINUX   ?= v5.2
          ROOTDEV_LIST ?= /dev/ram0 /dev/nfs
          ROOTDEV ?= /dev/ram0
    [ mipsel/ls232 ]:
          ARCH     = mips
          CPU     ?= mips32r2
          LINUX   ?= v2.6.32-r190726
          ROOTDEV_LIST := /dev/ram0 /dev/nfs
          ROOTDEV ?= /dev/ram0
    [ mipsel/malta ]:
          ARCH     = mips
          CPU     ?= mips32r2
          LINUX   ?= v5.1
          ROOTDEV_LIST := /dev/hda /dev/ram0 /dev/nfs
          ROOTDEV ?= /dev/ram0
    [ ppc/g3beige ]:
          ARCH     = powerpc
          CPU     ?= generic
          LINUX   ?= v5.1
          ROOTDEV_LIST := /dev/hda /dev/ram0 /dev/nfs
          ROOTDEV ?= /dev/ram0
    [ riscv32/virt ]:
          ARCH     = riscv
          CPU     ?= any
          LINUX   ?= v5.0.13
          ROOTDEV_LIST := /dev/vda /dev/ram0 /dev/nfs
          ROOTDEV ?= /dev/vda
    [ riscv64/virt ]:
          ARCH     = riscv
          CPU     ?= any
          LINUX   ?= v5.1
          ROOTDEV_LIST := /dev/vda /dev/ram0 /dev/nfs
          ROOTDEV ?= /dev/vda
    [ x86_64/pc ]:
          ARCH     = x86
          CPU     ?= qemu64
          LINUX   ?= v5.1
          ROOTDEV_LIST := /dev/hda /dev/ram0 /dev/nfs
          ROOTDEV_LIST[LINUX_v3.2] := /dev/sda /dev/ram0 /dev/nfs
          ROOTDEV ?= /dev/ram0
    [ csky/virt ]:
          ARCH     = csky
          CPU     ?= ck810
          LINUX   ?= v4.9.56
          ROOTDEV ?= /dev/nfs

`ARCH`, `FILTER` arguments are supported:

$ make list ARCH=arm
    $ make list FILTER=virt

and more:

$ make list-board         # only ARCH
    $ make list-short         # ARCH and LINUX
    $ make list-base          # no plugin
    $ make list-plugin        # only plugin
    $ make list-full          # everything

### 3.1.2 Choosing a board

By default, the default board: `vexpress-a9` is used, we can configure, build and boot for a specific board with `BOARD`, for example:

$ make BOARD=malta
    $ make boot

If several boards have the same name, please specify the architecture to distinguish:

$ make BOARD=mipsel/malta

Currently, such boards have the same name:

$ make list FILTER=virt
    [ aarch64/virt ]:
          ARCH     = arm64
          CPU     ?= cortex-a57
          LINUX   ?= v5.1
          ROOTDEV_LIST := /dev/sda /dev/vda /dev/ram0 /dev/nfs
          ROOTDEV ?= /dev/vda
    [ riscv32/virt ]:
          ARCH     = riscv
          CPU     ?= any
          LINUX   ?= v5.0.13
          ROOTDEV_LIST := /dev/vda /dev/ram0 /dev/nfs
          ROOTDEV ?= /dev/vda
    [ riscv64/virt ]:
          ARCH     = riscv
          CPU     ?= any
          LINUX   ?= v5.1
          ROOTDEV_LIST := /dev/vda /dev/ram0 /dev/nfs
          ROOTDEV ?= /dev/vda

$ make list FILTER=/pc
    [ i386/pc ]:
          ARCH     = x86
          CPU     ?= qemu32
          LINUX   ?= v5.1
          ROOTDEV_LIST ?= /dev/hda /dev/ram0 /dev/nfs
          ROOTDEV_LIST[LINUX_v2.6.34.9] ?= /dev/sda /dev/ram0 /dev/nfs
          ROOTDEV ?= /dev/hda
    [ x86_64/pc ]:
          ARCH     = x86
          CPU     ?= qemu64
          LINUX   ?= v5.1
          ROOTDEV_LIST := /dev/hda /dev/ram0 /dev/nfs
          ROOTDEV_LIST[LINUX_v3.2] := /dev/sda /dev/ram0 /dev/nfs
          ROOTDEV ?= /dev/ram0

Use them like this:

$ make BOARD=x86_64/pc
    $ make BOARD=riscv64/virt

If using `board`, it only works on-the-fly, the setting will not be saved, this is helpful to run multiple boards at the same and not to disrupt each other:

$ make board=malta boot

This allows to run multi boards in different terminals or background at the same time.

Check the board specific configuration:

$ cat boards/arm/vexpress-a9/Makefile

### 3.1.3 Using as plugins

The 'Plugin' feature is supported by Linux Lab, to allow boards being added and maintained in standalone git repositories. Standalone repository is very important to ensure Linux Lab itself not grow up big and big while more and more boards being added in.

Book examples or the boards with a whole new cpu architecture benefit from such feature a lot, for book examples may use many boards and a new cpu architecture may need require lots of new packages (such as cross toolchains and the architecture specific qemu system tool).

Here maintains the available plugins:

- [C-Sky Linux](https://gitee.com/tinylab/csky)
- [Loongson Linux](https://gitee.com/loongsonlab/loongson)

The Loongson plugin has been merged into v5.0.

### 3.1.4 Configure boards

Every board has its own configuration, some can be changed on demand, for example, memory size, linux version, buildroot version, qemu version and the other external devices, such as serial port, network devices and so on.

The configure method is very simple, just edit it by referring to current values (`boards/<BOARD>/Makefile`), this command open local configuration (`boards/<BOARD>/.labconfig`) via vim:

$ make local-edit

But please don't make a big change once, we often only need to tune linux version, this command is better for such case:

$ make list-linux
    v4.12 v4.5.5 v5.0.10 [v5.1]
    $ make local-config LINUX=v5.0.10
    $ make list-linux
    v4.12 v4.5.5 [v5.0.10] v5.1

If want to upstream your local changes, please use `board-edit` and `board-config`, otherwise, `local-edit` and `local-config` are preferrable, for they will avoid conflicts while pulling remote updates.

## 3.2 Build in one command

v0.3+ version add target dependency by default, so, if want to compile a kernel, just run:

$ make kernel-build

$ make build kernel

It will do everything required, of course, we still be able to run the targets explicitly.

And futher, with the timestamping support, finished targets will not be run again during the late operations, if still want, just clean the stamp and run it again:

$ make cleanstamp kernel-build
    $ make kernel-build

$ make force-kernel-build

To clean all of the stamp files:

$ make cleanstamp kernel

This function also support uboot, root and qemu.

## 3.3 Detailed Operations

### 3.3.1 Downloading

Download board specific package and the kernel, buildroot source code:

$ make source APP="bsp kernel root uboot"
    Or
    $ make source APP=all
    Or
    $ make source all

Download one by one:

$ make bsp-source
    $ make kernel-source
    $ make root-source
    $ make uboot-source

$ make source bsp
    $ make source kernel
    $ make source root
    $ make source uboot

After v0.5, the source code are downloaded in `src/`, before, they are saved in the root directory of Linux Lab.

### 3.3.2 Checking out

Checkout the target version of kernel and builroot:

$ make checkout APP="kernel root"

Checkout them one by one:

$ make kernel-checkout
    $ make root-checkout

$ make checkout kernel
    $ make checkout root

If checkout not work due to local changes, save changes and run to get a clean environment:

$ make kernel-cleanup
    $ make root-cleanup

$ make cleanup kernel
    $ make cleanup root

The same to qemu and uboot.

### 3.3.3 Patching

Apply available patches in `boards/<BOARD>/bsp/patch/linux` and `src/patch/linux/`:

$ make kernel-patch

$ make patch kernel

### 3.3.4 Configuration

#### 3.3.4.1 Default Configuration

Configure kernel and buildroot with defconfig:

$ make defconfig APP="kernel root"

Configure one by one, by default, use the defconfig in `boards/<BOARD>/bsp/`:

$ make kernel-defconfig
    $ make root-defconfig

$ make defconfig kernel
    $ make defconfig root

Configure with specified defconfig:

$ make B=raspi3
    $ make kernel-defconfig KCFG=bcmrpi3_defconfig
    $ make root-defconfig KCFG=raspberrypi3_64_defconfig

If only defconfig name specified, search boards/<BOARD> at first, and then the default configs path of buildroot, u-boot and linux-stable respectivly: src/buildroot/configs, src/u-boot/configs, src/linux-stable/arch/<ARCH>/configs.

#### 3.3.4.2 Manual Configuration

$ make kernel-menuconfig
    $ make root-menuconfig

$ make menuconfig kernel
    $ make menuconfig root

#### 3.3.4.3 Old default configuration

$ make kernel-olddefconfig
    $ make root-olddefconfig
    $ make uboot-olddefconfig

$ make olddefconfig kernel
    $ make olddefconfig root
    $ make olddefconfig uboot

### 3.3.5 Building

Build kernel and buildroot together:

$ make build APP="kernel root"

Build them one by one:

$ make kernel-build  # make kernel
    $ make root-build    # make root

$ make build kernel
    $ make build root

After v0.5, the building result are stored in `build/`, before they are put in `output/`.

### 3.3.6 Saving

Save all of the configs and rootfs/kernel/dtb images:

$ make save APP="kernel root"
    $ make saveconfig APP="kernel root"

Save configs and images to `boards/<BOARD>/bsp/`:

$ make kernel-saveconfig
    $ make root-saveconfig
    $ make root-save
    $ make kernel-save

$ make saveconfig kernel
    $ make saveconfig root
    $ make save kernel
    $ make save root

### 3.3.7 Booting

Boot with serial port (nographic) by default, exit with `CTRL+a x`, `poweroff`, `reboot` or `pkill qemu` (See [poweroff hang](#poweroff-hang)):

$ make boot

Boot with graphic (Exit with `CTRL+ALT+2 quit`):

$ make b=pc boot G=1 LINUX=v5.1
    $ make b=versatilepb boot G=1 LINUX=v5.1
    $ make b=g3beige boot G=1 LINUX=v5.1
    $ make b=malta boot G=1 LINUX=v2.6.36
    $ make b=vexpress-a9 boot G=1 LINUX=v4.6.7 // LINUX=v3.18.39 works too

**Note**: real graphic boot require LCD and keyboard drivers, the above boards work well, with linux v5.1,
  `raspi3` and `malta` has tty0 console but without keyboard input.

`vexpress-a9` and `virt` has no LCD support by default, but for the latest qemu, it is able to boot
  with G=1 and switch to serial console via the 'View' menu, this can not be used to test LCD and
  keyboard drivers. `XOPTS` specify the eXtra qemu options.

$ make b=vexpress-a9 CONSOLE=ttyAMA0 boot G=1 LINUX=v5.1
    $ make b=raspi3 CONSOLE=ttyAMA0 XOPTS="-serial vc -serial vc" boot G=1 LINUX=v5.1

Boot with curses graphic (friendly to bash/ssh login, not work for all boards, exit with `ESC+2 quit` or `ALT+2 quit`):

$ make b=pc boot G=2 LINUX=v4.6.7

Boot with PreBuilt Kernel, Dtb and Rootfs:

$ make boot PBK=1 PBD=1 PBR=1
    or
    $ make boot k=old d=old r=old
    or
    $ make boot kernel=old dtb=old root=old

Boot with new kernel, dtb and rootfs if exists:

$ make boot PBK=0 PBD=0 PBR=0
    or
    $ make boot k=new d=new r=new
    or
    $ make boot kernel=new dtb=new root=new

Boot with new kernel and uboot, build them if not exists:

$ make boot BUILD="kernel uboot"

Boot without Uboot (only `versatilepb` and `vexpress-a9` boards tested):

$ make boot U=0

Boot with different rootfs (depends on board, check `/dev/` after boot):

$ make boot ROOTDEV=/dev/ram      // support by all boards, basic boot method
    $ make boot ROOTDEV=/dev/nfs      // depends on network driver, only raspi3 not work
    $ make boot ROOTDEV=/dev/sda
    $ make boot ROOTDEV=/dev/mmcblk0
    $ make boot ROOTDEV=/dev/vda      // virtio based block device

Boot with extra kernel command line (XKCLI = eXtra Kernel Command LIne):

$ make boot ROOTDEV=/dev/nfs XKCLI="init=/bin/bash"

List supported options:

$ make list ROOTDEV
    $ make list BOOTDEV
    $ make list CCORI
    $ make list NETDEV
    $ make list LINUX
    $ make list UBOOT
    $ make list QEMU

And more `<xxx>-list` are also supported with `list <xxx>`, for example:

$ make list features
    $ make list modules
    $ make list gcc

# 4. Linux Lab Advance

## 4.1 Using Linux Kernel

### 4.1.1 non-interactive configuration

A tool named `scripts/config` in linux kernel is helpful to get/set the kernel
config options non-interactively, based on it, both of `kernel-getconfig`
and `kernel-setconfig` are added to tune the kernel options, with them, we
can simply "enable/disable/setstr/setval/getstate" of a kernel option or many
at the same time:

Get state of a kernel module:

$ make kernel-getconfig m=minix_fs
    Getting kernel config: MINIX_FS ...

build/aarch64/linux-v5.1-virt/.config:CONFIG_MINIX_FS=m

Enable a kernel module:

$ make kernel-setconfig m=minix_fs
    Setting kernel config: m=minix_fs ...

build/aarch64/linux-v5.1-virt/.config:CONFIG_MINIX_FS=m

Enable new kernel config: minix_fs ...

More control commands of `kernel-setconfig` including `y, n, c, o, s, v`:

| Option | Description
|--------|-----------------------------------------------------------
|`y`     | build the modules in kernel or enable anther kernel options.
|`c`     | build the modules as pluginable modules, just like `m`.
|`o`     | build the modules as pluginable modules, just like `m`.
|`n`     | disable a kernel option.
|`s`     | `RTC_SYSTOHC_DEVICE="rtc0"`, set the rtc device to rtc0
|`v`     | `v=PANIC_TIMEOUT=5`, set the kernel panic timeout to 5 secs.

Operates many options in one command line:

$ make kernel-setconfig m=tun,minix_fs y=ikconfig v=panic_timeout=5 s=DEFAULT_HOSTNAME=linux-lab n=debug_info
    $ make kernel-getconfig o=tun,minix,ikconfig,panic_timeout,hostname

### 4.1.2 using kernel modules

Build all internel kernel modules:

$ make modules
    $ make modules-install
    $ make root-rebuild     // not need for nfs boot
    $ make boot

List available modules in `src/modules/`, `boards/<BOARD>/bsp/modules/`:

$ make module-list

If `m` argument specified, list available modules in `src/modules/`, `boards/<BOARD>/bsp/modules/` and `src/linux-stable/`:

$ make module-list m=hello
         1	m=hello ; M=$PWD/modules/hello
    $ make module-list m=tun,minix
         1	c=TUN ; m=tun ; M=drivers/net
         2	c=MINIX_FS ; m=minix ; M=fs/minix

Enable one kernel module:

$ make kernel-getconfig m=minix_fs
    Getting kernel config: MINIX_FS ...

build/aarch64/linux-v5.1-virt/.config:CONFIG_MINIX_FS=m

$ make kernel-setconfig m=minix_fs
    Setting kernel config: m=minix_fs ...

build/aarch64/linux-v5.1-virt/.config:CONFIG_MINIX_FS=m

Enable new kernel config: minix_fs ...

Build one kernel module (e.g. minix.ko):

$ make module M=fs/minix/
    Or
    $ make module m=minix

Install and clean the module:

$ make module-install M=fs/minix/
    $ make module-clean M=fs/minix/

More flexible usage:

$ make kernel-setconfig m=tun
    $ make kernel x=tun.ko M=drivers/net
    $ make kernel x=drivers/net/tun.ko
    $ make kernel-run drivers/net/tun.ko

Build external kernel modules (the same as internel modules):

$ make module m=hello
    Or
    $ make kernel x=$PWD/modules/hello/hello.ko

### 4.1.3 using kernel features

Kernel features are abstracted in `src/feature/linux/, including their
configurations patchset, it can be used to manage both of the out-of-mainline
and in-mainline features.

$ make feature-list
    [ /labs/linux-lab/src/feature/linux ]:
      + 9pnet
      + core
        - debug
        - module
      + ftrace
        - v2.6.36
          * env.g3beige
          * env.malta
          * env.pc
          * env.versatilepb
        - v2.6.37
          * env.g3beige
      + gcs
        - v2.6.36
          * env.g3beige
          * env.malta
          * env.pc
          * env.versatilepb
      + kft
        - v2.6.36
          * env.malta
          * env.pc
      + uksm
        - v2.6.38

Verified boards and linux versions are recorded there, so, it should work
without any issue if the environment not changed.

For example, to enable kernel modules support, simply do:

$ make feature f=module
    $ make kernel-olddefconfig
    $ make kernel

For `kft` feature in v2.6.36 for malta board:

$ make BOARD=malta
    $ export LINUX=v2.6.36
    $ make kernel-checkout
    $ make kernel-patch
    $ make kernel-defconfig
    $ make feature f=kft
    $ make kernel-olddefconfig
    $ make kernel
    $ make boot

### 4.1.3 Create new development branch

If want to use a new development branch, please follow such steps:

At first, Get into `src/linux-stable` or another directory specified with `KERNEL_SRC`, checkout a development branch from a specific version:

$ cd src/linux-stable
    $ git checkout -b linux-v5.1-dev v5.1

And then, clone the necessary configurations and directories for our new branch.

$ make kernel-clone LINUX=v5.1 LINUX_NEW=linux-v5.1-dev

The v5.1 must be the already supported version, if not, please use the near one in supported list, for example, `i386/pc` board support such versions:

$ make b=i386/pc list linux
    v2.6.10 v2.6.11.12 v2.6.12.6 v2.6.21.5 v2.6.24.7 v2.6.34.9 v2.6.35.14 v2.6.36 v4.6.7 [v5.1] v5.2

If want to develop v2.6.38, please try to clone one from v2.6.36:

$ cd src/linux-stable
    $ git checkout -b linux-v2.6.38-dev v2.6.38
    $ make kernel-clone LINUX=v2.6.36 LINUX_NEW=linux-v2.6.38-dev

In development, please commit asap, and also, please use such commands carefully to avoid destroy your important changes:

* kernel-checkout, checkout a specified kernel version, may override your changes
* kernel-cleanup, clean up git repository, may remove your changes
* kernel-clean, clean building history, may run cleanup automatically

## 4.2 Using Uboot Bootloader

Choose one of the tested boards: `versatilepb` and `vexpress-a9`.

$ make BOARD=vexpress-a9

Download Uboot:

$ make uboot-source

Checkout the specified version:

$ make uboot-checkout

Patching with necessary changes, `BOOTDEV` and `ROOTDEV` available, use `flash` by default.

$ make uboot-patch

Use `tftp`, `sdcard` or `flash` explicitly, should run `make uboot-checkout` before a new `uboot-patch`:

$ make uboot-patch BOOTDEV=tftp
    $ make uboot-patch BOOTDEV=sdcard
    $ make uboot-patch BOOTDEV=flash

`BOOTDEV` is used to specify where to store and load the images for uboot, `ROOTDEV` is used to tell kernel where to load the rootfs.

Configure:

$ make uboot-defconfig
    $ make uboot-menuconfig

Building:

$ make uboot

Boot with `BOOTDEV` and `ROOTDEV`, use `flash` by default:

$ make boot U=1

Use `tftp`, `sdcard` or `flash` explicitly:

$ make boot U=1 BOOTDEV=tftp
    $ make boot U=1 BOOTDEV=sdcard
    $ make boot U=1 BOOTDEV=flash

We can also change `ROOTDEV` during boot, for example:

$ make boot U=1 BOOTDEV=flash ROOTDEV=/dev/nfs

Clean images if want to update ramdisk, dtb and uImage:

$ make uboot-images-clean
    $ make uboot-clean

Save uboot images and configs:

$ make uboot-save
    $ make uboot-saveconfig

## 4.3 Using Qemu Emulator

Builtin qemu may not work with the newest linux kernel, so, we need compile and
add external prebuilt qemu, this has been tested on vexpress-a9 and virt board.

At first, build qemu-system-ARCH:

$ make B=vexpress-a9

$ make qemu-download
    $ make qemu-checkout
    $ make qemu-patch
    $ make qemu-defconfig
    $ make qemu
    $ make qemu-save

qemu-ARCH-static and qemu-system-ARCH can not be compiled together. to build
qemu-ARCH-static, please enable `QEMU_US=1` in board specific Makefile and
rebuild it.

If QEMU and QTOOL specified, the one in bsp submodule will be used in advance of
one installed in system, but the first used is the one just compiled if exists.

While porting to newer kernel, Linux 5.0 hangs during boot on qemu 2.5, after
compiling a newer qemu 2.12.0, no hang exists. please take notice of such issue
in the future kernel upgrade.

If already download qemu and its submodules and don't want to upadte the submodules,
just skip it:

$ make qemu git_module_status=0

## 4.4 Using Toolchains

The pace of Linux mainline is very fast, builtin toolchains can not keep up, to
reduce the maintaining pressure, external toolchain feature is added. for
example, ARM64/virt, CCVER and CCPATH has been added for it.

List available prebuilt toolchains:

$ make gcc-list

Download, decompress and enable the external toolchain:

$ make gcc

Switch compiler version if exists, for example:

$ make gcc-switch CCORI=internal GCC=4.7

$ make gcc-switch CCORI=linaro

If not external toolchain there, the builtin will be used back.

If no builtin toolchain exists, please must use this external toolchain feature, currently, aarch64, arm, riscv, mipsel, ppc, i386, x86_64 support such feature.

GCC version can be configured in board specific Makefile for Linux, Uboot, Qemu and Root, for example:

GCC[LINUX_v2.6.11.12] = 4.4

With this configuration, GCC will be switched automatically during defconfig and compiling of the specified Linux v2.6.11.12.

To build host tools, host gcc should be configured too(please specify b=`i386/pc` explicitly):

$ make gcc-list b=i386/pc
    $ make gcc-switch CCORI=internal GCC=4.8 b=i386/pc

## 4.5 Using Rootfs

Builtin rootfs is minimal, is not enough for complex application development,
which requires modern Linux distributions.

Such a type of rootfs has been introduced and has been released as docker
image, ubuntu 18.04 is added for arm32v7 at first, more later.

Run it via docker directly:

$ docker run -it tinylab/arm32v7-ubuntu

Extract it out and run in Linux Lab:

(host)$ sudo apt-get install qemu-user-static

ARM32/vexpress-a9 (user: root, password: root):

(host)$ tools/root/docker/extract.sh tinylab/arm32v7-ubuntu arm
    (lab )$ make boot B=vexpress-a9 U=0 V=1 MEM=1024M ROOTDEV=/dev/nfs ROOTFS=$PWD/prebuilt/fullroot/tmp/tinylab-arm32v7-ubuntu

ARM64/raspi3 (user: root, password: root):

(host)$ tools/root/docker/extract.sh tinylab/arm64v8-ubuntu arm
    (lab )$ make boot B=raspi3 V=1 ROOTDEV=/dev/mmcblk0 ROOTFS=$PWD/prebuilt/fullroot/tmp/tinylab-arm64v8-ubuntu

More rootfs from docker can be found:

$ docker search arm64 | egrep "ubuntu|debian"
    arm64v8/ubuntu   Ubuntu is a Debian-based Linux operating system  25
    arm64v8/debian   Debian is a Linux distribution that's composed  20

## 4.6 Debugging Linux and Uboot

### 4.6.1 Debugging Linux

Compile the kernel with debugging options:

$ make feature f=debug
    $ make kernel-olddefconfig
    $ make kernel

Compile with one thread:

$ make kernel JOBS=1

And then debug it directly:

$ make debug

If login via `vnc` or `webvnc`, It will open a new terminal, load the scripts from `.gdb/kernel.default`, run gdb automatically.

But if login with `bash`, `ssh` or `webssh`, please read the prompt and run this command again to start debugging:

$ make debug

To customize kernel gdbinit script, simply copy one and edit it manually:

$ cp .gdb/kernel.default .gdb/kernel.user

It equals to:

$ make debug linux
    or
    $ make boot DEBUG=linux

to automate debug testing:

$ make test-debug linux
    or
    $ make test DEBUG=linux

find out the code line of a kernel panic address:

$ make kernel-calltrace func+offset/length

### 4.6.2 Debugging Uboot

To debug uboot with `.gdb/uboot.default`:

$ make debug uboot
    or
    $ make boot DEBUG=uboot

If login with `vnc` or `webvnc`, the above command will open a terminal and start debugging automatically.

But if login with `bash`, `ssh` or `webssh`, please read the prompt and run this command again to start real debugging:

$ make debug uboot

To automate uboot debug testing:

$ make test-debug uboot
    or
    $ make test DEBUG=uboot

The same to kernel gdbinit script, customize one for uboot:

$ cp .gdb/uboot.default .gdb/uboot.user

## 4.7 Test Automation

Use `aarch64/virt` as the demo board here.

$ make BOARD=virt

Prepare for testing, install necessary files/scripts in `src/system/`:

$ make rootdir
    $ make root-install
    $ make root-rebuild

Simply boot and poweroff (See [poweroff hang](#poweroff-hang)):

$ make test

Don't poweroff after testing:

$ make test TEST_FINISH=echo

Run guest test case:

$ make test TEST_CASE=/tools/ftrace/trace.sh

Run guest test cases (`COMMAND_LINE_SIZE` must be big enough, e.g. 4096, see `cmdline_size` feature below):

$ make test TEST_BEGIN=date TEST_END=date TEST_CASE='ls /root,echo hello world'

Reboot the guest system for several times:

$ make test TEST_REBOOT=2

NOTE: reboot may 1) hang, 2) continue; 3) timeout killed, TEST_TIMEOUT=30; 4) timeout continue, TIMEOUT_CONTINUE=1

Test a feature of a specified linux version on a specified board(`cmdline_size` feature is for increase `COMMAND_LINE_SIZE` to 4096):

$ make test f=kft LINUX=v2.6.36 b=malta TEST_PREPARE=board-init,kernel-cleanup

NOTE: `board-init` and `kernel-cleanup` make sure test run automatically, but `kernel-cleanup` is not safe, please save your code before use it!!

Test a kernel module:

$ make test m=hello

Test multiple kernel modules:

$ make test m=exception,hello

Test modules with specified ROOTDEV, nfs boot is used by default, but some boards may not support network:

$ make test m=hello,exception TEST_RD=/dev/ram0

Run test cases while testing kernel modules (test cases run between insmod and rmmod):

$ make test m=exception TEST_BEGIN=date TEST_END=date TEST_CASE='ls /root,echo hello world' TEST_PREPARE=board-init,kernel-cleanup f=cmdline_size

Run test cases while testing internal kernel modules:

$ make test m=lkdtm TEST_BEGIN='mount -t debugfs debugfs /mnt' TEST_CASE='echo EXCEPTION ">" /mnt/provoke-crash/DIRECT'

Run test cases while testing internal kernel modules, pass kernel arguments:

$ make test m=lkdtm lkdtm_args='cpoint_name=DIRECT cpoint_type=EXCEPTION'

Run test without feature-init (save time if not necessary):

$ make test m=lkdtm lkdtm_args='cpoint_name=DIRECT cpoint_type=EXCEPTION' TEST_INIT=0
    Or
    $ make raw-test m=lkdtm lkdtm_args='cpoint_name=DIRECT cpoint_type=EXCEPTION'

Run test with module and the module's necessary dependencies (check with `make kernel-menuconfig`):

$ make test m=lkdtm y=runtime_testing_menu,debug_fs lkdtm_args='cpoint_name=DIRECT cpoint_type=EXCEPTION'

Run test without feature-init, boot-init, boot-finish and no `TEST_PREPARE`:

$ make boot-test m=lkdtm lkdtm_args='cpoint_name=DIRECT cpoint_type=EXCEPTION'

Test a kernel module and make some targets before testing:

$ make test m=exception TEST=kernel-checkout,kernel-patch,kernel-defconfig

Test everything in one command (from download to poweroff, see [poweroff hang](#poweroff-hang)):

$ make test TEST=kernel,root TEST_PREPARE=board-init,kernel-cleanup,root-cleanup

Test everything in one command (with uboot while support, e.g. vexpress-a9):

$ make test TEST=kernel,root,uboot TEST_PREPARE=board-init,kernel-cleanup,root-cleanup,uboot-cleanup

Test kernel hang during boot, allow to specify a timeout, timeout must happen while system hang:

$ make test TEST_TIMEOUT=30s

Test kernel debug:

$ make test DEBUG=1

## 4.8 File Sharing

To transfer files between Qemu Board and Host, three methods are supported by
default:

### 4.8.1 Install files to rootfs

Simply put the files with a relative path in `src/system/`, install and rebuild the rootfs:

$ mkdir src/system/root/
    $ touch src/system/root/new_file
    $ make root-install
    $ make root-rebuild
    $ make boot

### 4.8.2 Share with NFS

Boot the board with `ROOTDEV=/dev/nfs`:

$ make boot ROOTDEV=/dev/nfs

Host:

$ make env-dump VAR=ROOTDIR
    ROOTDIR="/labs/linux-lab/boards/<BOARD>/bsp/root/<BUILDROOT_VERSION>/rootfs"

### 4.8.3 Transfer via tftp

Using tftp server of host from the Qemu board with the `tftp` command.

Host:

$ ifconfig br0
    inet addr:172.17.0.3  Bcast:172.17.255.255  Mask:255.255.0.0
    $ cd tftpboot/
    $ ls tftpboot
    kft.patch kft.log

Qemu Board:

$ ls
    kft_data.log
    $ tftp -g -r kft.patch 172.17.0.3
    $ tftp -p -r kft.log -l kft_data.log 172.17.0.3

**Note**: while put file from Qemu board to host, must create an empty file in host firstly. Buggy?

### 4.8.4 Share with 9p virtio

To enable 9p virtio for a new board, please refer to [qemu 9p setup](https://wiki.qemu.org/Documentation/9psetup). qemu must be compiled with `--enable-virtfs`, and kernel must enable the necessary options.

Reconfigure the kernel with:

CONFIG_NET_9P=y
    CONFIG_NET_9P_VIRTIO=y
    CONFIG_NET_9P_DEBUG=y (Optional)
    CONFIG_9P_FS=y
    CONFIG_9P_FS_POSIX_ACL=y
    CONFIG_PCI=y
    CONFIG_VIRTIO_PCI=y
    CONFIG_PCI_HOST_GENERIC=y (only needed for the QEMU Arm 'virt' board)

If using `-virtfs` or `-device virtio-9p-pci` option for qemu, must enable the above PCI related options, otherwise will not work:

9pnet_virtio: no channels available for device hostshare
    mount: mounting hostshare on /hostshare failed: No such file or directory

`-device virtio-9p-device` requires less kernel options.

To enable the above options, please simply type:

$ make feature f=9pnet
    $ make kernel-olddefconfig

Docker host:

$ modprobe 9pnet_virtio
    $ lsmod | grep 9p
    9pnet_virtio           17519  0
    9pnet                  72068  1 9pnet_virtio

Host:

$ make BOARD=virt

$ make root-install	       # Install mount/umount scripts, ref: src/system/etc/init.d/S50sharing
    $ make root-rebuild

$ touch hostshare/test     # Create a file in host

$ make boot U=0 ROOTDEV=/dev/ram0 PBR=1 SHARE=1

$ make boot SHARE=1 SHARE_DIR=src/modules   # for external modules development

$ make boot SHARE=1 SHARE_DIR=build/aarch64/linux-v5.1-virt/   # for internal modules learning

$ make boot SHARE=1 SHARE_DIR=src/examples   # for c/assembly learning

Qemu Board:

$ ls /hostshare/       # Access the file in guest
    test
    $ touch /hostshare/guest-test   # Create a file in guest

Verified boards with Linux v5.1:

| boards          | Status
|-----------------|---------------------------------------------------
|aarch64/virt     | virtio-9p-device (virtio-9p-pci breaks nfsroot)
|arm/vexpress-a9  | only work with virtio-9p-device and without uboot booting
|arm/versatilepb  | only work with virtio-9p-pci
|x86_64/pc        | only work with virtio-9p-pci
|i386/pc          | only work with virtio-9p-pci
|riscv64/virt     | work with virtio-9p-pci and virtio-9p-dev
|riscv32/virt     | work with virtio-9p-pci and virtio-9p-dev

## 4.9 Learning Assembly

Linux Lab has added many assembly examples in `src/examples/assembly`:

$ cd src/examples/assembly
    $ ls
    aarch64  arm  mips64el	mipsel	powerpc  powerpc64  README.md  x86  x86_64
    $ make -s -C aarch64/
    Hello, ARM64!

## 4.10 Learning C

### 4.10.1 Host build and Run

Use hello as example:

$ cd src/examples/c/hello
    $ make
    gcc -fno-stack-protector -fomit-frame-pointer -fno-asynchronous-unwind-tables -fno-pie -no-pie -m32 -Wall -Werror -g -o hello hello.c
    Hello, World!

### 4.10.2 Cross build and Run

Use ARM, MIPS and RISCV as example:

$ sudo apt-get install libc6-dev-armel-cross libc6-armel-cross
    $ arm-linux-gnueabi-gcc -o hello hello.c
    $ qemu-arm -E LD_LIBRARY_PATH=$$LD_LIBRARY_PATH:/usr/arm-linux-gnueabi/lib/ /usr/arm-linux-gnueabi/lib/ld-2.31.so ./hello
    Hello, World!

$ sudo apt-get install libc6-dev-mipsel-cross libc6-mipsel-cross
    $ mipsel-linux-gnu-gcc -o hello hello.c
    $ qemu-mipsel -E LD_LIBRARY_PATH=$$LD_LIBRARY_PATH:/usr/mipsel-linux-gnu/lib/ /usr/mipsel-linux-gnu/lib/ld-2.30.so ./hello
    Hello, World!

$ sudo apt-get install libc6-riscv64-cross libc6-dev-riscv64-cross
    $ riscv64-linux-gnu-gcc -o hello hello.c
    $ qemu-riscv64 -E LD_LIBRARY_PATH=$$LD_LIBRARY_PATH:/usr/riscv64-linux-gnu/lib/ /usr/riscv64-linux-gnu/lib/ld-2.31.so ./hello
    Hello, World!

Above run through `qemu-user`, to run on target boards, please copy the binaries to target boards' rootfs with help from section 4.8.1.

## 4.11 Running any make goals

Linux Lab allows to access Makefile goals easily via `<xxx>-run`, for example:

$ make kernel-run help
    $ make kernel-run menuconfig

$ make root-run help
    $ make root-run busybox-menuconfig

$ make uboot-run help
    $ make uboot-run menuconfig

`-run` goals allows to run sub-make goals of kernel, root and uboot directly without entering into their own building directory.

## 4.12 More Usage

* [Why Using Linux Lab V1.0 (In Chinese)](http://tinylab.org/why-linux-lab)
* [Why Using Linux Lab V2.0 (In Chinese)](http://tinylab.org/why-linux-lab-v2)

# 5. Linux Lab Development

This introduces how to add a new board for Linux Lab.

## 5.1 Choose a board supported by qemu

list the boards, use arm as an example:

$ qemu-system-arm -M ?

## 5.2 Create the board directory

Use `vexpress-a9` as an example:

$ mkdir boards/arm/vexpress-a9/

## 5.3 Clone a Makefile from an existing board

Use `versatilepb` as an example:

$ cp boards/arm/versatilebp/Makefile boards/arm/vexpress-a9/Makefile

## 5.4 Configure the variables from scratch

Comment everything, add minimal ones and then others.

Please refer to `doc/qemu/qemu-doc.html` or the online one <http://qemu.weilnetz.de/qemu-doc.html>.

## 5.5 At the same time, prepare the configs

We need to prepare the configs for linux, buildroot and even uboot.

Buildroot has provided many examples about buildroot and kernel configuration:

buildroot: src/buildroot/configs/qemu_ARCH_BOARD_defconfig
    kernel: src/buildroot/board/qemu/ARCH-BOARD/linux-VERSION.config

Uboot has also provided many default configs:

uboot: src/u-boot/configs/vexpress_ca9x4_defconfig

Kernel itself also:

kernel: src/linux-stable/arch/arm/configs/vexpress_defconfig

Linux Lab itself also provide many working configs too, the `xxx-clone` target is a
good helper to utilize existing configs:

$ make list kernel
    v4.12 v5.0.10 v5.1
    $ make kernel-clone LINUX=v5.1 LINUX_NEW=v5.4
    $ make kernel-menuconfig
    $ make kernel-saveconfig

$ make list root
    2016.05 2019.02.2
    $ make root-clone BUILDROOT=2019.02.2 BUILDROOT_NEW=2019.11
    $ make root-menuconfig
    $ make root-saveconfig

Edit the configs and Makefile untill they match our requirements.

$ make kernel-menuconfig
    $ make root-menuconfig
    $ make board-edit

The configuration must be put in `boards/<BOARD>/` and named with necessary
version info, use `raspi3` as an example:

$ make kernel-saveconfig
    $ make root-saveconfig
    $ ls boards/aarch64/raspi3/bsp/configs/
    buildroot_2019.02.2_defconfig  linux_v5.1_defconfig

`2019.02.2` is the buildroot version, `v5.1` is the kernel version, both of these
variables should be configured in `boards/<BOARD>/Makefile`.

More usage about the `xxx-clone` commands:

$ make qemu-clone QEMU=<old_version> QEMU_NEW=<new_version>
    $ make uboot-clone UBOOT=<old_version> UBOOT_NEW=<new_version>
    $ make kernel-clone LINUX=<old_version> LINUX_NEW=<new_version>
    $ make root-clone BUILDROOT=<old_version> BUILDROOT_NEW=<new_version>

## 5.6 Choose the versions of kernel, rootfs and uboot

Please use `tag` instead of `branch`, use kernel as an example:

$ cd src/linux-stable
    $ git tag
    ...
    v5.0
    ...
    v5.1
    ..
    v5.1.1
    v5.1.5
    ...

If want v5.1 kernel, just put a line "LINUX = v5.1" in `boards/<BOARD>/Makefile`.

Or clone a kernel config from the old one or the official defconfig:

$ make kernel-clone LINUX_NEW=v5.3 LINUX=v5.1

$ make B=i386/pc
    $ pushd linux-stable && git checkout v5.4 && popd
    $ make kernel-clone LINUX_NEW=v5.4 KCFG=i386_defconfig

If no tag existed, a virtual tag name with the real commmit number can be configured as following:

LINUX = v2.6.11.12
    LINUX[LINUX_v2.6.11.12] = 8e63197f

Linux version specific ROOTFS are also supported:

ROOTFS[LINUX_v2.6.12.6]  ?= $(BSP_ROOT)/$(BUILDROOT)/rootfs32.cpio.gz

## 5.7 Configure, build and boot them

Use kernel as an example:

$ make kernel-defconfig
    $ make kernel-menuconfig
    $ make kernel
    $ make boot

The same to rootfs, uboot and even qemu.

## 5.8 Save the images and configs

$ make root-save
    $ make kernel-save
    $ make uboot-save

$ make root-saveconfig
    $ make kernel-saveconfig
    $ make uboot-saveconfig

## 5.9 Upload everything

At last, upload the images, defconfigs, patchset to board specific bsp submodule repository.

Firstly, get the remote bsp repository address as following:

$ git remote show origin
    * remote origin
      Fetch URL: https://gitee.com/tinylab/qemu-aarch64-raspi3/
      Push  URL: https://gitee.com/tinylab/qemu-aarch64-raspi3/
      HEAD branch: master
      Remote branch:
        master tracked
      Local branch configured for 'git pull':
        master merges with remote master
      Local ref configured for 'git push':
        master pushes to master (local out of date)

Then, fork this repository from gitee.com, upload your changes, and send your pull request.

# 6. FAQs

## 6.1 Docker Issues

### 6.1.1 Speed up docker images downloading

To optimize docker images download speed, please edit `DOCKER_OPTS` in `/etc/default/docker` via referring to `tools/docker/install`.

### 6.1.2 Docker network conflicts with LAN

We assume the docker network is `10.66.0.0/16`, if not, we'd better change it as following:

$ sudo vim /etc/default/docker
    DOCKER_OPTS="$DOCKER_OPTS --bip=10.66.0.10/16"

$ sudo vim /lib/systemd/system/docker.service
    ExecStart=/usr/bin/dockerd -H fd:// --bip=10.66.0.10/16

Please restart docker service and lab container to make this change works:

$ sudo service docker restart
    $ tools/docker/rerun linux-lab

If lab network still not work, please try another private network address and eventually to avoid conflicts with LAN address.

### 6.1.3 Why not allow running Linux Lab in local host

The full function of Linux Lab depends on the full docker environment managed by [Cloud Lab](http://tinylab.org/cloud-lab), so, please really never try and therefore please don't complain about why there are lots of packages missing failures and even the other weird issues.

Linux Lab is designed to use pre-installed environment with the docker technology and save our life by avoiding the packages installation issues in different systems, so, Linux Lab would never support local host using even in the future.

### 6.1.4 Run tools without sudo

To use the tools under `tools` without sudo, please make sure add your account to the docker group and reboot your system to take effect:

$ sudo usermod -aG docker <USER>
    $ newgrp docker

### 6.1.5 Network not work

If ping not work, please check one by one:

* DNS issue

if `ping 8.8.8.8` work, please check `/etc/resolv.conf` and make sure it is the same as your host configuration.

* IP issue

if ping not work, please refer to [network conflict issue](#docker-network-conflicts-with-lan) and change the ip range of docker containers.

### 6.1.6 Client.Timeout exceeded while waiting headers

This means must configure one of the following docker mirror sites:

* [Aliyun Docker Mirror Documentation](https://help.aliyun.com/document_detail/60750.html)
  * [USTC Docker Mirror Documentation](https://lug.ustc.edu.cn/wiki/mirrors/help/docker)

Potential methods of configuration in Ubuntu, depends on docker and ubuntu versions:

`/etc/default/docker`:

echo "DOCKER_OPTS=\"\$DOCKER_OPTS --registry-mirror=<your accelerate address>\""

`/lib/systemd/system/docker.service`:

ExecStart=/usr/bin/dockerd -H fd:// --bip=10.66.0.10/16 --registry-mirror=<your accelerate address>

`/etc/docker/daemon.json`:

{
        "registry-mirrors": ["<your accelerate address>"]
    }

Please restart docker service after change the accelerate address:

$ sudo service docker restart

For the other Linux systems, Windows and MacOS System, please refer to [Aliyun Mirror Speedup Document](https://help.aliyun.com/document_detail/60750.html).

IF still slow, please check if the mirror site is configured normally and without typos:

$ docker info | grep -A1 -i Mirrors
     Registry Mirrors:
      https://XXXXX.mirror.aliyuncs.com/

### 6.1.7 Restart Linux Lab after host system shutdown or reboot

If want to restore the installed softwares and related configurations, please save the container manually:

$ tools/docker/commit linux-lab

After host system (include virtual machine) shutdown or reboot, you can restart the lab via the "Linux Lab" icon on the desktop, or just like before, issue this command:

$ tools/docker/run linux-lab

Current implementation doesn't support the direct 'docker start' command, please learn it.

If the above methods still not restart the lab, please refer to the methods mentioned in the 6.3.9 section.

If resume from a suspended host system, the lab will restore automatically, no need to do anything to restart it, just use one of the 4 login methods mentioned in the 2.4 section, for example, start a web browser to connect it:

$ tools/docker/vnc

## 6.2 Qemu Issues

### 6.2.1 Why kvm speedding up is disabled

kvm only supports both of `qemu-system-i386` and `qemu-system-x86_64` currently, and it also requires the cpu and bios support, otherwise, you may get this error log:

modprobe: ERROR: could not insert 'kvm_intel': Operation not supported

Check cpu virtualization support, if nothing output, then, cpu not support virtualization:

$ cat /proc/cpuinfo | egrep --color=always "vmx|svm"

If cpu supports, we also need to make sure it is enabled in bios features, simply reboot your computer, press 'Delete' to enter bios, please make sure the 'Intel virtualization technology' feature is 'enabled'.

### 6.2.2 Poweroff hang

Both of the `poweroff` and `reboot` commands not work on these boards currently (LINUX=v5.1):

* mipsel/malta (exclude LINUX=v2.6.36)
  * mipsel/ls232
  * mipsel/ls1b
  * mips64el/ls2k
  * mips64el/ls3a7a
  * aarch64/raspi3
  * arm/versatilepb

System will directly hang there while running `poweroff` or `reboot`, to exit qemu, please pressing `CTRL+a x` or using `pkill qemu`.

To test such boards automatically, please make sure setting `TEST_TIMEOUT`, e.g. `make test TEST_TIMEOUT=50`.

Welcome to fix up them.

### 6.2.3 How to exit qemu

| Where                 |  How
|-----------------------|---------------------------------------
| Serial Port Console   | `CTRL+a x`
| Curses based Graphic  | `ESC+2 quit` Or `ALT+2 quit`
| X based Graphic       | `CTRL+ALT+2 quit`
| Generic Methods       | `poweroff`, `reboot`, `kill`, `pkill`

### 6.2.4 Boot with missing sdl2 libraries failure

That's because the docker image is not updated, just rerun the lab (please must not use `tools/docker/restart` here for it not using the new docker image):

$ tools/docker/pull linux-lab
    $ tools/docker/rerun linux-lab

$ tools/docker/update linux-lab

With `tools/docker/update`, every docker images and source code will be updated, it is preferred.

## 6.3 Environment Issues

### 6.3.1 NFS/tftpboot not work

If nfs or tftpboot not work, please run `modprobe nfsd` in host side and restart the net services via `/configs/tools/restart-net-servers.sh` and please
make sure not use `tools/docker/trun`.

### 6.3.2 How to switch windows in vim

`CTRL+w` is used in both of browser and vim, to switch from one window to another, please use `CTRL+Left` or `CTRL+Right` key instead, Linux Lab has remapped `CTRL+Right` to `CTRL+w` and `CTRL+Left` to `CTRL+p`.

### 6.3.3 How to delete typo in shell command line

Long keypress not work in novnc client currently, so, long `Delete` not work, please use `alt+delete` or `alt+backspace` instead, more tips:

|Function                  | Vim           | Bash                      |
|--------------------------|---------------|---------------------------|
|begin/end                 | `^/$`         | `Ctrl + a/e`              |
|forward/backward          | `w/b`         | `Ctrl + Home/end`         |
|cut one word backword     | `db`          | `Alt  + Delete/backspace` |
|cut one word forward      | `dw`          | `Alt  + d`                |
|cut all to begin          | `d^`          | `Ctrl + u`                |
|cut all to end            | `d$`          | `Ctrl + k`                |
|paste all cutted          | `p`           | `Ctrl + y`                |

### 6.3.4 Language input switch shortcuts

In order to switch English/Chinese input method, please use `CTRL+s` shortcuts, it is used instead of `CTRL+space` to avoid conflicts with local system.

### 6.3.5 How to tune the screen size

There are tow methods to tune the screen size, one is auto scaling by noVNC, another is pre-setting during launching.

The first one is setting noVNC before connecting.

* Press the left sidebar of noVNC web page
    * Disconnect
    * Enable 'Auto Scaling Mode' via 'Settings -> Scaling Mode: -> Local Scaling -> Apply'
    * Connect

The second one is setting `SCREEN_SIZE` while running Linux Lab.

The screen size of lab is captured by xrandr, if not work, please check and set your own, for example:

Get available screen size values:

$ xrandr --current
    Screen 0: minimum 1 x 1, current 1916 x 891, maximum 16384 x 16384
    Virtual1 connected primary 1916x891+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
       1916x891      60.00*+
       2560x1600     59.99
       1920x1440     60.00
       1856x1392     60.00
       1792x1344     60.00
       1920x1200     59.88
       1600x1200     60.00
       1680x1050     59.95
       1400x1050     59.98
       1280x1024     60.02
       1440x900      59.89
       1280x960      60.00
       1360x768      60.02
       1280x800      59.81
       1152x864      75.00
       1280x768      59.87
       1024x768      60.00
       800x600       60.32
       640x480       59.94

Before running rm command, please save all of your data, for example, save the container:

$ tools/docker/commit linux-lab

Choose one and configure it:

$ cd /path/to/cloud-lab
    $ tools/docker/rm-all
    $ SCREEN_SIZE=800x600 tools/docker/run linux-lab

If want the default one, please remove the manual setting at first:

$ cd /path/to/cloud-lab
    $ rm configs/linux-lab/docker/.screen_size
    $ tools/docker/rm-all
    $ tools/docker/run linux-lab

### 6.3.6 How to work in fullscreen mode

Open the left sidebar, press the 'Fullscreen' button.

### 6.3.7 How to record video

* Enable recording

Open the left sidebar, press the 'Settings' button, config 'File/Title/Author/Category/Tags/Description' and enable the 'Record Screen' option.

* Start recording

Press the 'Connect' button.

* Stop recording

Press the 'Disconnect' button.

* Replay recorded video

Press the 'Play' button.

* Share it

Videos are stored in 'cloud-lab/recordings', share it with help from [showdesk.io](http://showdesk.io/post).

### 6.3.8 Linux Lab not response

The VNC connection may hang for some unknown reasons and therefore Linux Lab may not response sometimes, to restore it, please press the flush button of web browser or re-connect after explicitly disconnect.

### 6.3.9 VNC login with failures

If VNC login return "Disconnect timeout", wait a while and press the left 'Connect' button again, otherwise, check as following:

At first, check the containers' status (Up: Ok, Exit: Bad):

$ docker ps -a
    CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
    19a61ba075b5 tinylab/linux-lab "/tools/lab/run" 4 days ago Up 4 days 22/tcp, 5900/tcp linux-lab-21575
    75dae89984c9 tinylab/cloud-ubuntu-web "/startup.sh" 8 days ago Up 8 days ....443/tcp cloud-ubuntu-web

If the status is 'Exit', that means container may be shutdown or may never up, run it again to resume for the shutdown case:

$ tools/docker/run linux-lab

Otherwise, check the running logs:

$ tools/docker/logs linux-lab

If normal, that means the login account and password may have been invalid for some exceptions, please regenerte new account and password with the coming steps:

**Note**: The `clean` command will remove some containers and data, please do necessary backup before run it, for example, save the container:

$ tools/docker/commit linux-lab

VNC login fails while using mismatched password, to fix up such issue, please clean up all and rerun it:

$ tools/docker/clean linux-lab
    $ tools/docker/rerun linux-lab

If the above command not work, please try this one (**It will clean more data, please do necessary backup**)

$ tools/docker/clean-all
    $ tools/docker/rerun linux-lab

### 6.3.10 Ubuntu Snap Issues

Users report many snap issues, please use apt-get instead:

* users can not be added to docker group and break non-root operation.
  * snap service exhausts the /dev/loop devices and break mount operation.

### 6.3.11 How to exit fullscreen mode of vnc clients

The easiest method is kill the VNC server in Linux Lab:

$ sudo pkill x11vnc

## 6.4 Lab Issues

### 6.4.1 No working init found

This means the rootfs.ext2 image may be broken, please remove it and try `make boot` again, for example:

$ rm boards/aarch64/raspi3/bsp/root/2019.02.2/rootfs.ext2
    $ make boot

`make boot` command can create this image automatically.

### 6.4.2 linux/compiler-gcc7.h: No such file or directory

This means using a newer gcc than the one linux kernel version supported, the solution is [switching to an older gcc version](#toolchain) via `make gcc-switch`, use `i386/pc` board as an example:

$ make gcc-list
    $ make gcc-switch CCORI=internal GCC=4.4

### 6.4.3 linux-lab/configs: Permission denied

This may happen at `make boot` while the repository is cloned with `root` user, please simply update the owner of `cloud-lab/` directory:

$ cd /path/to/cloud-lab
    $ sudo chown <USER>:<USER> -R ./
    $ tools/docker/rerun linux-lab

To make a consistent working environment, Linux Lab only support using as general user: 'ubuntu'.

### 6.4.4 scripts/Makefile.headersinst: Missing UAPI file

This means MAC OSX not use Case sensitive filesystem, create one using `hdiutil` or `Disk Utility` yourself:

### 6.4.5 unable to create file: net/netfilter/xt_dscp.c

This means Windows not enable filesystem's case sensitive feature, just enable it:

$ cd /path/to/cloud-lab
    $ fsutil file SetCaseSensitiveInfo ./ enable

### 6.4.6 how to run as root

By default, no password required to run as root with:

$ sudo -s

### 6.4.7 not in supported list

Such information means the specified value is not supported currently:

$ make boot ROOTDEV=vda
    ERR: /dev/vda not in supported ROOTDEV list: /dev/sda /dev/ram0 /dev/nfs, update may help: 'make bsp B=mips64el/ls3a7a'.  Stop.

$ make boot LINUX=v5.8
    Makefile:594: *** ERR: v5.8 not in supported LINUX list: loongnix-release-1903 v5.7, clone one please: 'make kernel-clone KERNEL_NEW=v5.8'.  Stop.

$ make boot QEMU=loongson-v1.1
    Makefile:606: *** ERR: loongson-v1.1 not in supported QEMU list: loongson-v1.0, clone one please: 'make qemu-clone QEMU_NEW=loongson-v1.1'.

There are two main types:

* One is the specified version is not there or has not been verified
    * Please clone one and verify it with the usage of `xxx-clone` from section 5.

* Another is the specified value is invalid or simply not verified
    * For example, the above vda is not added in the `ROOTDEV_LIST`
    * This board may not support such type of device or just nobody verify and add it
    * This differs from board and kernel version

# 7. Contact and Sponsor

Our contact wechat is **tinylab**, welcome to join our user & developer discussion group.

**Contact us and Sponsor via wechat:**

![contact-sponsor](doc/images/contact-sponsor.png)

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