</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
-
-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)。
-
-## 1. 一些实用资源
+# 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!
+
+
+|  |
+|:--:|
+| *Lunaix over serial* (`console=/dev/ttyS0`) |
+
+|  |
+|:--:|
+| *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>
+
+## Documentations
+
+There are documentations avaliable if you want to dig deeper. Keep in mind they are still work in progress and missing localisation.
+
++ [Luna's Tour - Into Lunaix's Inner Workings](docs/lunaix-internal.md)
++ [Syscall Number Assignments](docs/lunaix-syscall-table.md)
+
+## Compile and Build
+
+Building lunaix is simple, no more bloated dependencies to install, basic
+`build-essentials` installation plus a python are sufficient.
+
++ gcc (recommend v12+)
++ binutils
++ make
++ python (recommend v3.11+)
-如果有意研读LunaixOS的内核代码和其中的设计，以下资料可能会对此有用。
+And also one should have environment variable `ARCH=<arch>` exported, where
+`<arch>` is one of the supported arhcitecture (`x86_32`, `x86_64`, `aarch64`).
-+ [内核虚拟内存的详细布局](docs/img/lunaix-os-mem.png)
-+ [LunaixOS启动流程概览](docs/img/boot_sequence.jpeg)
-+ LunaixOS总体架构概览（WIP）
+For cross compilation, also export `CX_PREFIX` to the gcc prefix for the
+corresponding `<arch>`.
-## 2. 当前进度以及支持的功能
+The following `make` actions are then available to use.
-该操作系统支持x86架构，运行在保护模式中，采用宏内核架构，目前仅支持单核心。架构与内核的解耦合工作正在进行中。
+| 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 |
-在下述列表中，则列出目前所支持的所用功能和特性。列表项按照项目时间戳进行升序排列。
+A successful build will give `build/bin/kernel.bin`.
-+ 使用Multiboot进行引导启动
-+ APIC/IOAPIC作为中断管理器和计时器
-+ ACPI
-+ 虚拟内存
-+ 内存管理与按需分页
-+ 键盘输入
-+ 多进程
-+ 54个常见的Linux/POSIX系统调用（[附录1](#appendix1)）
-+ 用户模式
-+ 信号机制
-+ PCI 3.0
-+ PCIe 1.1 (WIP)
-+ Serial ATA AHCI
-+ 文件系统
- + 虚拟文件系统
- + ISO9660
- + 原生
- + Rock Ridge拓展
-+ 远程GDB串口调试 (COM1@9600Bd)
-+ 用户程序加载与执行
-+ 动态链接 (WIP)
-+ 通用设备抽象层
-+ 通用图形设备抽象层
- + 标准VGA实现
-+ 虚拟终端设备接口（兼容 POSIX.1-2008）
+> Please note: this is the kernel, not a bootable image, it require a bootloader
+> to boot and specify the rootfs.
-已经测试过的环境：
+## Get Started
-+ QEMU (>=7.0.0)
-+ Bochs（SATA功能不支持）
-+ Virtualbox
-+ Dell G3 3779
+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).
-## 3. 目录结构
+### Quick Start
-| | |
-| ----------------------------------------- | ---------------------------- |
-| [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 |
+This will get you up and running real quick. We will use `x86_64` as example.
-## 4. 编译与构建
+Assuming a Linux or other Unix-like shell environment. We also expect you to be able to sort out trivial issues like missing packages.
-构建该项目需要满足以下条件：
+**Select your target**
+```sh
+$ export ARCH=x86_64
+```
-+ gcc 工具链
-+ make
-+ xorriso
-+ grub-mkrescue
+**Check Python**
+```sh
+$ python --version
+```
-### 4.1 使用 GNU CC 工具链
+Ensure at least `3.11`
-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。至于其他的工具链，如llvm，也可以去尝试，但对此我就不能作任何的保证了。
+**Check compiler**
+```sh
+$ gcc -dumpmachine
+```
-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：
+Ensure `x86_64-linux-gnu` or anything resemble `x86_64`
-```
-make CX_PREFIX=i686-linux-gnu- all
+**Check QEMU**
+```sh
+$ which qemu-system-x86_64
```
-由于目前Lunaix仅支持x86_32微架构， `CX_PREFIX` 指向的gcc必须具有针对x86_32架构进行交叉编译的能力。
+Should display a valid installation path
-### 4.2 Docker镜像
+**Optional: Setting up Cross-Compiler**
-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)。
+```sh
+$ export CX_PREFIX=x86_64-linux-gnu-
+```
-### 4.3 构建选项
+**Run Configuration**
+```sh
+make config
+```
-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。
+Then hitting `q` in the interactive shell to accept default setting.
-本项目支持的make命令：
-| 命令 | 用途 |
-| ------------------------ | ----------------------------------------------- |
-| `make all` | 构建镜像（`-O2`，但禁用CSE相关的优化项 **※** ） |
-| `make instable` | 构建镜像（`-O2`，开启CSE相关优化） |
-| `make all-debug` | 构建适合调试用的镜像（`-Og`） |
-| `make run` | 使用QEMU运行build目录下的镜像 |
-| `make debug-qemu` | 构建并使用QEMU进行调试 |
-| `make debug-bochs` | 构建并使用Bochs进行调试 |
-| `make debug-qemu-vscode` | 用于vscode整合 |
-| `make clean` | 删除build目录 |
+**Build stock rootfs**
-**※：由于在`-O2`模式下，GCC会进行CSE优化，这导致LunaixOS会出现一些非常奇怪、离谱的bug，从而影响到基本运行。具体原因有待调查。**
+```sh
+make rootfs
+```
-### 4.4 设置内核启动参数
+Note, this requires root for creating fs image. You can check script `lunaix-os/scripts/mkrootfs` if you feel uncertain.
-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：
+**Build & Run**
+```sh
+./live_debug.sh
+```
-+ `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）
+you should see gdb now take control of your shell
-如果`CMDLINE`未指定，则将会载入默认参数：
+**Connect to serial via telnet**
-```
-console=/dev/ttyFB0
+Open up another window or session
+```sh
+telnet localhost 12345
```
-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。
+**Commence simulation**
-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。
+Back to the gdb session and type `c` to countine
-**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）
-## 5. 运行，分支以及 Issue
+**Watch Lunaix booting!**
-### 5.1 虚拟磁盘（非必须）
+Congrats, enjoy your lunaix! (or submit an issue)
-你可以绑定一个虚拟磁盘镜像，可以使用如下命令快速创建一个：
-```bash
-qemu-img create -f vdi machine/disk0.vdi 128M
-```
+### Not so Quick Start
-如果你想要使用别的磁盘镜像，需要修改`configs/make-debug-tool`
+Here is a slower and yet more verbose steps:
-找到这一行：
+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)
-```
--drive id=disk,file="machine/disk0.vdi",if=none \
-```
-然后把`machine/disk0.vdi`替换成你的磁盘路径。
+## Booting the kernel
-有很多办法去创建一个虚拟磁盘，比如[qemu-img](https://qemu-project.gitlab.io/qemu/system/images.html)。
+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.
-### 5.2 代码稳定性
+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
-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。
+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)
+Currently, lunaix support the following options
-下面列出一些可能会出现的问题。
+| 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` |
-#### 问题#1： QEMU下8042控制器提示找不到
-这是QEMU配置ACPI时的一个bug，在7.0.0版中修复了。
+## Submit an Issue
-#### 问题#2：多进程运行时，偶尔会出现General Protection错误
+If one ran into bug, one can submit an issue by filling up the following template
-这很大概率是出现了竞态条件。虽然是相当不可能的。但如果出现了，还是请提issue。
+```
+1. Describe the problem
+ "How does it look like, anything descriptive: visual, sonic, emotional experience"
-#### 问题#3：Bochs无法运行，提示找不到AHCI控制器
+2. Steps to reproduce
+ "How you ran into this mess?"
-正常，**因为Bochs不支持SATA**。请使用QEMU或VirtualBox。
+3. Expected behaviour
+ "What do you intended/expected to achieve/to be"
-## 6. 调试 Lunaix 内核
+4. Lunaix's panic trace (if applicable)
-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：
+5. Other clues that you think might be helpful
+```
-+ `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）。
-+ `proc_table` 列举所有非终止的进程以及他们的状态。
-+ `syslog` 打印到目前为止的系统日志。
-该插件可以通过运行以下命令来进行安装：
+## Limitations
-```shell
-./scripts/gdb/install_lunadbg
-```
+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.
-## 7. 参考教程
+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
-**没有！！** 本教程以及该操作系统均为原创，没有基于任何市面上现行的操作系统开发教程，且并非是基于任何的开源内核的二次开发。
+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.
-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）。
+## Acknowledgement
-大部分的文档和标准可以在上述的[reference-material](reference-material/)中找到。
+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.
-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）：
+As a personal challenge, this project is independently developed by the author
+single-handly, which means:
-#### 手册，标准，技术文档
++ 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.
-+ [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)
+## References
+
++ 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)
+ 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。
-+ [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：支持的系统调用<a id="appendix1"></a>
-
-**Unix/Linux/POSIX**
-
-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`)
-
-**LunaixOS自有**
-
-1. `yield`
-2. `geterrno`
-3. `realpathat`
-4. `syslog`
-5. `pollctl`
-
-( **※**：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
git://scm.lunaixsky.com / lunaix-os.git / blobdiff