X-Git-Url: https://scm.lunaixsky.com/lunaix-os.git/blobdiff_plain/04f32c3e67120f8498cdcf7926bab88e4e405258..765e0decea6bf192187728e46dc8d4b652b4f1fc:/README.md

diff --git a/README.md b/README.md
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--- a/README.md
+++ b/README.md
@@ -3,227 +3,378 @@
 </p>
 
 <p align="center">
-  <a href="#lunaixos-project">简体中文</a> | <a href="docs/README_en.md">English</a>
+  <a href="docs/README.cn.md">简体中文</a> | <a href="#the-lunaixos-project">English</a>
 </p>
 
-# The LunaixOS Project
+# The Lunaix Project
+
+The Lunaix kernel (or soon-to-be LunaixOS) is a hobby kernel, started in 2022, 
+written entirely from scratch. With a big ambition of being POSIX-compliance, 
+and designed with performance and modernity in mind, with some independent 
+thoughts being applied in architectural design.
+
+
+This project is built entirely from first principles - meaning no code was 
+copy-pasted or recycled from other OS projects or tutorials. Lunaix didn't begin 
+as an attempt to outperform anything; it started as a personal challenge to 
+learn OS theory and explore advanced kernel features through original design 
+and implementation. Everything you see here was developed solo, part-time, 
+with only hardware specs and my beloved **Modern Operating Systems** as guidance.
+
+If you're a kernel hobbyist looking for a fresh take or tired of mass-produced, tutorial-style 
+projects, then welcome, you're in the right place!
+
+
+| ![showcase_lunaix-over-serial.png](docs/img/showcase_lunaix-over-serial.png) |
+|:--:|
+| *Lunaix over serial* (`console=/dev/ttyS0`) |
+
+| ![showcase_lunaix-over-serial.png](docs/img/showcase_lunaix-over-vga-text.png) |
+|:--:|
+| *Lunaix over VGA text mode* (`console=/dev/ttyVCON0`) |
+
+> By the way, do you know there is an online video course  by the author on the design of lunaix? [Check it out](https://space.bilibili.com/12995787/channel/collectiondetail?sid=196337) (although it is in Chinese!)
+
+## Features
+
+Lunaix is a multi-architecture, general-purpose kernel built with performance, 
+modularity, and robustness in mind. Its design emphasizes advanced abstractions, 
+proactive error detection, and subsystem isolation. Lunaix is
+
++ **Fully-preemptive** for responsive multi-tasking
++ **Modular** with compile-time configurable components and extensible 
+  subsystems
++ **High-performance**, leveraging modern caching strategies and efficient 
+  infrastructures.
++ **Fault-tolerant**, with built-in error handling and stack backtracing
++ **Robust by design**, using mechanisms like proactive deadlock detection 
+  and driver isolation
+
+A significant amount of effort has gone into crafting clean abstractions, 
+implementing advanced kernel features, and applying performance optimizations 
+throughout the system.
+
+To better illustrate the scope of work already done, the following non-exhaustive 
+list outlines currently supported features in Lunaix:
+
+### List of All Features
+<details>
+
+<summary>Click to Expand</summary>
+
++ Multi-ISA
+  + x86_32
+  + x86_64
+  + Aarch64 (WIP)
++ Boot protocol
+  + abstraction for different protocol
+  + configurable kernel boot-time parameters
++ Platform resource management and definition
+  + read-only ACPI table interpretation
+  + full devicetree implementation
++ Memory management
+  + architecture-neutral abstraction
+  + highmem
+  + copy-on-write
+  + page sharing
+  + explicit huge page
+  + on-demand paging
+  + compound page
+  + reverse mapping (rmap)
+  + memory compaction (WIP)
+  + slab-style object allocator
+  + inter-process address space access
++ Multi-tasking
+  + fully preemptive
+  + protection levels
+  + process isolation
+  + native threading
+  + signal mechanism
+  + round-robin scheduler (for now)
+  + kernel level multi-tasking (i.e. kernel threads)
+  + taskfs: file system interface to process and threads
++ File system
+  + POSIX-compliant interface
+  + virtual file system framework
+  + file system mounting mechanism
+  + page cache for file IO
+  + inode/dnode caching
+  + ext2 (rev.0, rev.1)
+  + iso9660 (rock-ridge)
+  + twifs: kernel state fs interface.
++ Device management and interrupt handling
+  + unified IRQ framework
+  + unified driver framework for heterogenous devices
+  + modular driver model allow compiled-time toggling
+  + asynchronous operation model supported
+  + devfs: device fs interface.
++ Block I/O (blkio)
+  + unified block IO interface
+  + IO request packets caching
+  + asynchronous IO operation
++ Serial I/O
+  + POSIX-compliant serial IO model
++ Caching Infrastructure
+  + LRU replacement policy and pooling
+  + kernel daemon for dynamic and transparent cache managements
++ Error handling and detection
+  + stack backtracing with symbol resolution
+  + stack unwinding for nested exception
+  + CPU state dumping
+  + deadlock/hung-up detection
+
+</details>
+
+### List of Built-in Drivers
+
+<details>
+
+<summary>Click to Expand</summary>
+
++ Architecture Neutral
+  + UART 16650-compatible driver
+  + Serial ATA AHCI
+  + PCI 3.0
+  + PCIe 1.1
+  + Standard VGA
++ Intel x86
+  + RTC (Intel PCH)
+  + IOAPIC IRQ controller
+  + APIC Timer
+  + Legacy i8042 keyboard controller
++ ARM
+  + GICv3
+  + PL011 (WIP)
+</details>
 
-LunaixOS - 一个简单的，详细的，POSIX兼容的（但愿！），带有浓重个人风格的操作系统。开发过程以视频教程形式在Bilibili呈现：[《从零开始自制操作系统系列》](https://space.bilibili.com/12995787/channel/collectiondetail?sid=196337)。
+## Documentations
 
-## 1. 一些实用资源
+There are documentations avaliable if you want to dig deeper. Keep in mind they are still work in progress and missing localisation.
 
-如果有意研读LunaixOS的内核代码和其中的设计，或欲开始属于自己的OS开发之道，以下资料可能会对此有用。
++ [Luna's Tour - Into Lunaix's Inner Workings](docs/lunaix-internal.md)
++ [Syscall Number Assignments](docs/lunaix-syscall-table.md)
 
-+ [最新的LunaixOS源代码分析教程](docs/tutorial/0-教程介绍和环境搭建.md)
-+ 内核虚拟内存的详细布局
-  + [x86_32](docs/img/lunaix-mem-map/lunaix-mem-x86_32.png)
-  + [x86_64](docs/img/lunaix-mem-map/lunaix-mem-x86_64.png)
-+ [LunaixOS启动流程概览](docs/img/boot_sequence.jpeg)
-+ LunaixOS总体架构概览（WIP）
-+ [作者修改的QEMU](https://github.com/Minep/qemu) (添加了一些额外用于调试的功能)
+## Compile and Build
 
-## 2. 当前进度以及支持的功能
+Building lunaix is simple, no more bloated dependencies to install, basic 
+`build-essentials` installation plus a python are sufficient.
 
-Lunaix内核具有支持多种不同的指令集架构的能力，目前支持如下：
++ gcc (recommend v12+)
++ binutils
++ make
++ python (recommend v3.11+)
 
-+ x86_32
-+ x86_64
+And also one should have environment variable `ARCH=<arch>` exported, where 
+`<arch>` is one of the supported arhcitecture (`x86_32`, `x86_64`, `aarch64`).
 
-Lunaix全部特性一览：
+For cross compilation, also export `CX_PREFIX` to the gcc prefix for the 
+corresponding `<arch>`.
 
-+ 使用Multiboot进行引导启动
-  + Multiboot 1
-  + Multiboot 2 (WIP)
-+ APIC/IOAPIC作为中断管理器和计时器
-+ ACPI
-+ 虚拟内存
-  + 架构中性设计
-  + 按需分页
-  + Copy-on-Write
-+ 内存管理
-+ 进程模型
-+ 61个常见的Linux/POSIX系统调用（[附录1](#appendix1)）
-+ 用户/内核态隔离
-+ 信号机制
-+ PCI 3.0
-+ PCIe 1.1 (WIP)
-+ 块设备驱动
-  + Serial ATA AHCI
-    + ATA设备
-    + ATAPI封装的SCSI协议
-+ 文件系统（POSIX.1-2008, section 5 & 10）
-  + 虚拟文件系统
-  + 内核态文件系统（twifs, Lunaix自己的sysfs）
-  + 设备文件系统（devfs, Lunaix自己的udev）
-  + 进程文件系统（procfs）
-  + ISO9660
-    + ECMA-119
-    + IEEE P1282（Rock Ridge拓展）
-+ 远程GDB串口调试 (COM1@9600Bd)
-+ 用户程序加载与执行
-+ 通用设备抽象层
-  + 架构中性的设备支持位于：`lunaix-os/hal`
-    + 16550 UART
-    + ACPI （不完全实现）
-  + 架构耦合的设备支持位于：`lunaix-os/arch/<ARCH>/hal`
-    + x86
-      + APIC/IOAPIC 组合
-      + MC146818 RTC
-      + i8042 PS/2
-      + RNG（使用`rdrand`）
-+ 通用图形设备抽象层 (Draft)
-  + 参考：`lunaix-os/hal/gfxa`
-+ 虚拟终端设备接口（POSIX.1-2008, section 11）
-  + 参考：`lunaix-os/hal/term`
-+ 线程模型
-  + 用户线程支持（pthread系列）
-  + 内核线程支持（抢占式内核设计）
-
-## 3. 目录结构
-
-|                                           |                              |
-| ----------------------------------------- | ---------------------------- |
-| [lunaix-os](lunaix-os/)                   | LunaixOS源代码               |
-| [slides](slides/)                         | 视频中所用的幻灯片和补充材料 |
-| [reference-material](reference-material/) | 标准，技术文档和参考文献     |
-
-## 4. 编译与构建
-
-**！如果想要立刻构建并运行，请参考4.6！**
-
-构建该项目需要满足以下条件：
-
-+ gcc 工具链
-+ make
-+ xorriso
-+ grub-mkrescue
+The following `make` actions are then available to use.
+
+| Make command | Usage |
+| ---- | ---- |
+| `make all`               | Build the kernel bin |
+| `make rootfs`            | Build the stock rootfs |
+| `make clean`             | clean |
+| `make config`            | run configuration tool |
+| `make reconfig`          | revert to default and restart configuration |
+
+A successful build will give `build/bin/kernel.bin`.
+
+> Please note: this is the kernel, not a bootable image, it require a bootloader 
+> to boot and specify the rootfs.
+
+## Get Started
 
-### 4.1 使用 GNU CC 工具链
+If you are impatient, or just want something to run and don't want to went 
+through tedious process of configuring rootfs and tweak kernel parameters. You 
+can use the `live_debug.sh` provided in the lunaix root directory to quickly 
+bring up the system with default parameters (also used by the author for 
+debugging).
 
-正如同大多数OS一样，LunaixOS 是一个混合了 C 和汇编的产物。这就意味着你得要使用一些标准的C编译器来构建Lunaix。在这里，我推荐使用 GNU CC 工具链来进行构建。因为Lunaix 在编写时使用了大量的GNU CC 相关编译器属性修饰 (`__attribute__`) 。假若使用其他工具链，如LLVM，我对此就不能做出任何保证了。
+### Quick Start
 
-如果你使用的是基于 x86 指令集的Linux系统，不论是64位还是32位，**其本机自带的gcc就足以编译Lunaix**。 当然了，如果说你的平台是其他非x86的，你也可以指定使用某个针对x86_32的gcc套件来进行交叉编译——在`make`时通过`CX_PREFIX`变量来指定gcc套件的前缀。如下例所示，我们可以在任意平台上，如risc-v，单独使用一个面向x86_32的gcc来进行交叉编译：
+This will get you up and running real quick. We will use `x86_64` as example.
 
+Assuming a Linux or other Unix-like shell environment. We also expect you to be able to sort out trivial issues like missing packages.
+
+**Select your target**
+```sh
+$ export ARCH=x86_64
 ```
-make CX_PREFIX=i686-linux-gnu- all
+
+**Check Python**
+```sh
+$ python --version
 ```
 
-### 4.2 Docker镜像
+Ensure at least `3.11`
 
-对于开发环境，本项目也提供了Docker镜像封装。开箱即用，无需配置，非常适合懒人或惜时者。详细使用方法请转到：[Lunaix OSDK项目](https://github.com/Minep/os-devkit)。
+**Check compiler**
+```sh
+$ gcc -dumpmachine
+```
 
-### 4.3 构建选项
+Ensure `x86_64-linux-gnu` or anything resemble `x86_64`
 
+**Check QEMU**
+```sh
+$ which qemu-system-x86_64
+```
 
-假若条件满足，那么可以直接执行`make all`进行构建，完成后可在生成的`build`目录下找到可引导的iso。
+Should display a valid installation path
 
-本项目支持的make命令：
-| 命令                     | 用途                                            |
-| ------------------------ | ----------------------------------------------- |
-| `make all`               | 等价于 `make image` |
-| `make image`             | 构建ISO镜像，可直接启动，使用ISO9660文件系统         |
-| `make kernel`            | 构建内核ELF镜像，无法直接启动，需要引导程序        |
-| `make clean`             | 删除构建缓存，用于重新构建               |
-| `make config`            | 配置Lunaix                                   |
+**Optional: Setting up Cross-Compiler**
 
-与make命令配套的环境变量，Lunaix的makefile会自动检测这些环境变量，以更改构建行为
+```sh
+$ export CX_PREFIX=x86_64-linux-gnu-
+```
 
-+ `MODE={debug|release}` 使用debug模式构建（-Og）或者release模式（-O2）
-+ `ARCH=<isa>` 为指定的指令集架构编译Lunaix。 所使用的配置选项均为选定架构默认，该环境变量
-  存在的目的就是方便用户进行快速编译，而无需钻研Lunaix的种种配置项。
+**Run Configuration**
+```sh
+make config
+```
 
-### 4.4 Lunaix的功能配置
+Then hitting `q` in the interactive shell to accept default setting.
 
-Lunaix是一个可配置的内核，允许用户在编译前选择应当包含或移除的功能。
+**Build stock rootfs**
 
-使用`make config`来进行基于命令行的交互配置。呈现方式采用Shell的形式，所有的配置项按照类似于文件树的形式组织，如单个配置项为一个“文件”，多个配置项组成的配置组为一个目录，呈现形式为方括号`[]`包裹起来的项目。在提示符中输入`usage`并回车可以查看具体的使用方法。
+```sh
+make rootfs
+```
 
-一个最常用的配置可能就是`architecture_support/arch`了，也就是配置Lunaix所面向的指令集。比如，编译一个在x86_64平台上运行的Lunaix，在提示符中输入（**注意等号两侧的空格，这是不能省略的**）：
+Note, this requires root for creating fs image. You can check script `lunaix-os/scripts/mkrootfs` if you feel uncertain.
 
+**Build & Run**
+```sh
+./live_debug.sh
 ```
-/architecture_support/arch = x86_64
+
+you should see gdb now take control of your shell
+
+**Connect to serial via telnet**
+
+Open up another window or session
+```sh
+telnet localhost 12345
 ```
 
-之后输入`exit`保存并推出。而后正常编译。
+**Commence simulation**
 
+Back to the gdb session and type `c` to countine
 
-### 4.5 设置内核启动参数
 
-在 make 的时候通过`CMDLINE`变量可以设置内核启动参数列表。该列表可以包含多个参数，通过一个或多个空格来分割。每个参数可以为键值对 `<key>=<val>` 或者是开关标志位 `<flag>`。目前 Lunaix 支持以下参数：
+**Watch Lunaix booting!**
 
-+ `console=<dev>` 设置系统终端的输入输出设备（tty设备）。其中 `<dev>` 是设备文件路径 （注意，这里的设备文件路径是针对Lunaix，而非Linux）。关于LunaixOS设备文件系统的介绍可参考 Lunaix Wiki（WIP）
+Congrats, enjoy your lunaix! (or submit an issue)
 
-如果`CMDLINE`未指定，则将会载入默认参数：
 
-```
-console=/dev/ttyFB0
-```
+### Not so Quick Start
 
-其中，`/dev/ttyFB0` 指向基于VGA文本模式的tty设备，也就是平时启动QEMU时看到的黑色窗口。
+Here is a slower and yet more verbose steps:
 
-当然，读者也可以使用 `/dev/ttyS0` 来作为默认tty设备，来验证 Lunaix 的灵活性与兼容性。该路径指向第一个串口设备。可以通过telnet协议在`12345`端口上进行访问——端口号可以自行修改QEMU启动参数（位于：`makeinc/qemu.mkinc`）来变更。
+1. Select an architecture `<arch>`
+2. Check the compilation prerequisites and presence of `qemu-system-<arch>`
+3. Optionally export `CX_PREFIX` if you are building for another architecture.
+4. Run `make ARCH=<arch> rootfs` to build stock rootfs image, require support 
+   of `dd`，`mkfs.ext2`, `mount -o loop`, `mktemp`.
+5. Run `ARCH=<arch> live_debug.sh` to boot in QEMU with gdb hooked (one should 
+   see a gdb session)
+6. telnet to `localhost:12345`, this is QEMU emulated serial port
+7. type `c` in the active gdb session and commence emulation.
+8. Congrats, enjoy your lunaix!
+(or submit an issue)
 
-**注意：** 根据操作系统和键盘布局的不同，telnet客户端对一些关键键位的映射（如退格，回车）可能有所差别（如某些版本的Linux会将退格键映射为`0x7f`，也就是ASCII的`<DEL>`字符，而非我们熟知`0x08`）。如果读者想要通过串口方式把玩Lunaix，请修改`usr/init/init.c`里面的终端初始化代码，将`VERASE`设置为正确的映射（修改方式可以参考 POSIX termios 的使用方式。由于Lunaix的终端接口的实现是完全兼容POSIX的，读者可以直接去查阅Linux自带的帮助`man termios`，无需作任何的转换）
 
-### 4.6 测试与体验 Lunaix
+## Booting the kernel
 
-用户可以使用脚本`live_debug.sh` 来快速运行Lunaix。 该脚本自动按照默认的选项构建Lunaix，而后调用 `scripts/qemu.py` 根据配置文件生成QEMU启动参数
-（配置文件位于`scripts/qemus/`）
+Since lunaix is a kernel, much like linux. It requires additional setup to do 
+the magic. And, as in "much like linux", methods to make linux kernel boot can 
+also apply to lunaix without or with little translation, as we will discuss 
+below.
 
-由于该脚本的主要用途是方便作者进行调试，所以在QEMU窗口打开后还需要进行以下动作：
+The bootloader part is generic, any bootloader, for example GRUB will work (not 
+tested for UEFI, but I expect this would be an exception), or booting up in QEMU 
+using `-kernel` option
 
-1. 使用telnet连接到`localhost:12345`，这里是Lunaix进行标准输入输出所使用的UART映射（QEMU为guest提供UART实现，并将其利用telnet协议重定向到宿主机）
-2. 在GDB窗口中输入`c`然后回车，此时Lunaix开始运行。这样做的目的是允许在QEMU进行模拟前，事先打好感兴趣的断点。
+The kernel command line, is however, a bit differentiated.
+The syntax is similar, both takes form of space-separated array of `<key>=<val>` 
+pairs or boolean `<flag>`.
 
-该脚本的运行需要设置 `ARCH=<isa>` 环境变量，其值需要与编译时制定的值一致。
+Currently, lunaix support the following options
 
-## 5. 运行，分支以及 Issue
+| Option | Default Value | Optional | Usage |
+| ------ | ----          |  -----   | ----  |
+| console | `/dev/ttyS0`   | No | Specify the system console device, path within lunaix's devfs |
+| rootfs | `/dev/block/sda` | No | Specify the device contain rootfs image, path within lunaix's devfs |
+| init | `/init` | Yes | Path within rootfs of the `init` |
 
-### 5.1 代码稳定性
 
-主分支一般是稳定的。因为在大多数情况下，我都会尽量保证本机运行无误后，push到该分支中。至于其他的分支，则是作为标记或者是开发中的功能。前者标记用分支一般会很快删掉；后者开发分支不能保证稳定性，这些分支的代码有可能没有经过测试，但可以作为Lunaix当前开发进度的参考。
+## Submit an Issue
 
-该系统是经过虚拟机和真机测试。如果发现在使用`make all`之后，虚拟机中运行报错，则一般是编译器优化问题。这个问题笔者一般很快就会修复，如果你使用别的版本的gcc（笔者版本11.2），出现了此问题，欢迎提issue。请参考[附录3：Issue的提交](#appendix3)
+If one ran into bug, one can submit an issue by filling up the following template
 
-## 6. 调试 Lunaix 内核
+```
+1. Describe the problem
+    "How does it look like, anything descriptive: visual, sonic, emotional experience"
 
-除了[附录4：串口GDB远程调试](#appendix4)描述的一种用于实机调试的方式以外。LunaixOS还提供了LunaDBG调试套件。这是一个GDB客户端插件，包含了对GDB原生命令集的一些扩充，主要用于改善与简化内核调试的过程。目前包含以下几个命令：
+2. Steps to reproduce
+    "How you ran into this mess?"
 
-+ `vmrs [pid]` 列举进程`<pid>`的内存区域图（Memory Regions），如果`<pid>`未指定，则默认为正在运行的进程（smp=1）。
-+ `proc [pid]` 打印进程`<pid>`的进程控制块状态，如果`<pid>`未指定，则默认为正在运行的进程（smp=1）。
-+ `sched <threads | procs> [-l]` 查看调度器信息，接受两个参数：
-  + `threads` 打印所有依然在调度器中有注册的线程
-  + `procs` 打印所有依然在调度器中有注册的进程
-  + 可选开关 `-l` 决定是否以长列表打印（更详细的信息）
+3. Expected behaviour
+    "What do you intended/expected to achieve/to be"
 
-该插件可以通过运行以下命令来进行安装：
+4. Lunaix's panic trace (if applicable)
 
-```shell
-./scripts/gdb/install_lunadbg
+5. Other clues that you think might be helpful
 ```
 
-## 7. 参考教程
 
-#### 没有！！
+## Limitations
+
+The development process is still in motion, any limitation can be categorised as 
+a feature yet to be. However, some features that the author considered to be the 
+most urgent and wish the matters to be discussed.
 
-本教程以及该操作系统的所有的架构设计与实现**均为原创**。
+Lunaix is under impression of uniprocessor and not capable of running in SMP 
+environment. This is major held back of being a modern operating system. It has 
+the highest priority among all other tasks
 
-对此，作者可以保证，该项目是做到了三个 “没有”：
+Lunaix do not have a mature (or even, an infant) user space ecosystem, mainly 
+because the lack of a proper and sophisticated libc. Efforts need to be done for 
+porting one to the target. However, given the author's tight schedule, this task 
+is unfortunately still beyond the horizon.
 
-+ **没有** 参考任何现行的，关于操作系统开发的，教程或书籍。
-+ **没有** 参考任何开源内核的源代码（包括Linux）
-+ **没有** 基于任何开源内核的二次开发行为。
+## Acknowledgement
 
-为了制作LunaixOS，作者耗费大量时间和精力钻研技术文档，手册，理论书籍以及现行工业标准，从而尽量保证了知识的一手性。（这样一来，读者和听众们也算是拿到了二手的知识，而不是三手，四手，甚至n手的知识）。
+Albeit one must realise that the author has mentioned it in the very beginning, 
+the author would like to emphaise **again** on the nature of this project.
 
-大部分的文档和标准可以在上述的[reference-material](reference-material/)中找到。
+As a personal challenge, this project is independently developed by the author 
+single-handly, which means:
 
-当然，您也可以参考以下列表来了解现阶段的LunaixOS都使用了哪些资料（本列表会随着开发进度更新）：
++ No reference to existing tutorials, books, online courses or any open source 
+  project that might provide any example, hint or working prototype on the 
+  design and implementation of kernel, subsystems or anythings that can be 
+  contributed towards a working prototype.
++ The author has no prior knowledge on Linux kernel through out 90% of the 
+  project time.
++ All knowledge on the kernel design is coming from the basic textbook on 
+  operating system theory, that is, *Modern Operating System* by Tanenbaum.
++ All knowledge on the system programming is coming from the basic textbook, 
+  that is, *Computer System - A Programmer's Perspective Third Edition*
++ All knowledge on the generic framework design and driver development are 
+  ingested from various technical specifications gathered across the Internet.
 
-#### 手册，标准，技术文档
+## References
 
-+ [Intel 64 and IA-32 Architecture Software Developer's Manual (Full Volume Bundle)](https://www.intel.com/content/www/us/en/developer/articles/technical/intel-sdm.html)
-+ [ACPI Specification (version 6.4)](https://uefi.org/sites/default/files/resources/ACPI_Spec_6_4_Jan22.pdf)
++ Intel 64 and IA-32 Architecture Software Developer's Manual (Full Volume Bundle)
++ ACPI Specification (version 6.4)
++ Devicetree Specification
++ ARM® Generic Interrupt Controller (v3)
++ Arm® Architecture Reference Manual (Profile-A)
++ Procedure Call Standard for the Arm® 64-bit Architecture (AArch64)
 + IBM PC/AT Technical Reference
 + IBM VGA/XGA Technical Reference
 + 82093AA I/O Advanced Programmable Controller (IOAPIC) (Datasheet)
@@ -236,116 +387,54 @@ console=/dev/ttyFB0
 + Serial ATA: High Speed Serialized AT Attachment, Revision 3.2
 + SCSI Command Reference Manual
 + ATA/ATAPI Command Set - 3 (ACS-3)
-+ [ECMA-119 (ISO9660)](https://www.ecma-international.org/publications-and-standards/standards/ecma-119/)
++ ECMA-119 (ISO9660)
 + Rock Ridge Interchange Protocol (RRIP: IEEE P1282)
 + System Use Sharing Protocol (SUSP: IEEE P1281)
 + Tool Interface Standard (TIS) Portable Formats Specification (Version 1.1)
++ *Computer System - A Programmer's Perspective Third Edition* (Bryant, R & O'Hallaron, D), a.k.a. CS:APP
++ *Modern Operating System* (Tanenbaum, A)
++ Free VGA, http://www.osdever.net/FreeVGA/home.htm 
++ GNU CC & LD online documentation.
++ PCI Lookup, https://www.pcilookup.com/
++ Linux man pages
 
-**免责声明：PCI相关的标准最终解释权归PCI-SIG所有。此处提供的副本仅供个人学习使用。任何商用目的须向PCI-SIG购买。**
+## Appendix 1: Supported System Call<a id="appendix1"></a>
 
-#### 理论书籍
+Refer to [Lunaix Syscall Table](docs/lunaix-syscall-table.md)
 
-+ *Computer System - A Programmer's Perspective Third Edition (CS:APP)* (Bryant, R & O'Hallaron, D)
-+ *Modern Operating System* (Tanenbaum, A)
+## Appendix 2: Debugging with GDB remotely via UART
+
+**(((( Broken after a refactoring years ago, need rework ))))**
+
+<details>
+<summary> Click to expand </summary>
+The LunaixOS kernel comes with a built-in GDB debugging server, which runs on 
+COM1@9600Bd. However, LunaixOS must be in debug mode before involving GDB.
+
+One could trigger the debug mode by writing a byte sequence `0x40` `0x63` `0x6D` 
+`0x63`, to the same serial port. A text "DEBUG MODE" with magenta-coloured background shall be present at the bottom of the screen.
+
+Note that, whenever the text appears, the LunaixOS always halt all activities 
+other than the debugging server, which means no scheduling and no external 
+interrupt servicing. Users are now recommended to attach their GDB and drive 
+the kernel with the debugging workflow.
+
+Currently, LunaixOS implements the required minimal server-side command subset 
+required by GDB Remote Protocol, namely, `g`, `G`, `p`, `P`, `Q`, `S`, `k`, `?`, 
+`m`, `M`, `X`. Which should be enough to cover most debugging activities.
+
+When debugging is finished, one shall disconnect with `kill` command. This 
+command will not force LunaixOS to power down the computer, instead it just 
+resume the execution (identical behavior as `c` command). However, disconnecting 
+does not means exiting of debug mode. The debug mode is still actived and any 
+subsequent GDB attaching request shall remain the highest priority amongst all 
+other activity. One shall deactivate the debug mode by writing byte sequence 
+`0x40` `0x79` `0x61` `0x79` to the port, after GDB detached.
+
+### Limitations
 
-#### 网站
-
-+ [OSDev](https://wiki.osdev.org/Main_Page) - 杂七杂八的参考，很多过来人的经验。作者主要用于上古资料查询以及收集；技术文献，手册，标准的粗略总结；以及开发环境/工具链的搭建。当然，上面的内容假设了x86_32架构的生态，对于其他的ISA支持，该网站便失去了其价值了。
-+ [FreeVGA](http://www.osdever.net/FreeVGA/home.htm) - 98年的资源！关于VGA编程技术的宝藏网站。
-+ GNU CC 和 GNU LD 的官方文档。
-+ [PCI Lookup](https://www.pcilookup.com/) - PCI设备编号查询
-
-#### 其他
-
-+ Linux Manual - 用于查询*nix API的一些具体行为。
-
-## 附录1：实现的 POSIX 系统接口 <a id="appendix1"></a>
-
-LunaixOS 提供对以下POSIX的系统接口的实现。内核定义的系统调用号可以参考 [LunaixOS系统调用表](docs/lunaix-syscall-table.md) 。
-
-1. `sleep(3)`
-1. `wait(2)`
-1. `waitpid(2)`
-1. `fork(2)`
-1. `getpid(2)`
-1. `getppid(2)`
-1. `getpgid(2)`
-1. `setpgid(2)`
-1. `brk(2)`
-1. `sbrk(2)`
-1. `_exit(2)`
-1. `sigreturn(2)`
-1. `sigprocmask(2)`
-1. `sigaction(2)`
-1. `kill(2)`
-1. `sigpending(2)`
-1. `sigsuspend(2)`
-2. `read(2)`
-2. `write(2)`
-2. `open(2)`
-2. `close(2)`
-2. `mkdir(2)`
-2. `lseek(2)`
-2. `readdir(2)`
-2. `readlink(2)`
-2. `readlinkat(2)`
-2. `rmdir(2)`※
-2. `unlink(2)`※
-2. `unlinkat(2)`※
-2. `link(2)`※
-2. `fsync(2)`※
-2. `dup(2)`
-2. `dup2(2)`
-2. `symlink(2)`
-2. `chdir(2)`
-2. `fchdir(2)`
-2. `getcwd(2)`
-2. `rename(2)`※
-2. `mount(2)`
-2. `unmount` (a.k.a `umount(2)`)※
-2. `getxattr(2)`※
-2. `setxattr(2)`※
-2. `fgetxattr(2)`※
-2. `fsetxattr(2)`※
-2. `ioctl(2)`
-2. `getpgid(2)`
-2. `setpgid(2)`
-2. `mmap(2)`
-2. `munmap(2)`
-2. `execve(2)`
-3. `poll(2)` (via `pollctl`)
-3. `epoll_create(2)` (via `pollctl`)
-3. `epoll_ctl(2)` (via `pollctl`)
-3. `epoll_wait(2)` (via `pollctl`)
-4. `pthread_create`
-4. `pthread_self`
-4. `pthread_exit`
-4. `pthread_join`
-4. `pthread_kill`
-4. `pthread_detach`
-4. `pthread_sigmask`
-
-
-( **※**：该系统调用暂未经过测试 )
-
-## 附录2：Issue的提交<a id="appendix3"></a>
-
-假若Lunaix的运行出现任何问题，还请按照以下的描述，在Issue里面提供详细的信息。
-
-+ 可用于复现问题的描述和指引（如Lunaix运行平台的软硬件配置）
-+ 错误症状描述
-+ LunaixOS在panic时打印的调试信息（如无法复制，可以截图）
-
-## 附录3：串口GDB远程调试<a id="appendix4"></a>
-
-**（该功能正在重构，目前不可用）**
-
-LunaixOS内核集成了最基本的GDB远程调试服务器。可通过串口COM1在9600波特率上与之建立链接。但是，在将GDB与内核链接起来之前，还需要让内核处在调试模式下。
-
-要进入调试模式，需要往串口（波特率如上）写入字节串 `0x40` `0x63` `0x6D` `0x63`。此时，如果屏幕底部出现一条品红色背景的`DEBUG` 字样，那么就说明LunaixOS已处在调试模式下。
-
-注意，在这个时候，LunaixOS会开始在`COM1`上监听GDB协议信息，并且暂停一切的活动（如调度，以及对外部中断的一切响应）。用户此时需要将GDB与其挂载，并使用GDB的工作流来指示内核下一步的动作。
-
-在目前，为了防止代码过于臃肿，LunaixOS实现的是GDB远程协议要求的最小服务端命令子集：`g`, `G`, `p`, `P`, `Q`, `S`, `k`, `?`, `m`, `M`, `X`。足以满足大部分的调试需求。
-
-当结束调试的时候，请使用GDB的`kill`指令进行连接的断开。注意，这个指令会使得LunaixOS恢复所有暂停的活动，进入正常的运行序列，但并不会退出调试模式。GDB的挂载请求依然在LunaixOS中享有最高优先权。如果需要退出调试模式，需要往串口写入字节串：`0x40` `0x79` `0x61` `0x79`。
+Currently, one should avoid the use of `info stack`, `bt` or any other command 
+that involves stack unwinding or stack backtracing. As it will somehow corrupt 
+the stack layout and result in undefined behaviour. This issue should be 
+addressed in future releases.
+</details>
\ No newline at end of file