ProtoType Operating System(PT-OS)

This is a simple Operating System, Which implements some useful component. All componnet of PT-OS is just ProtoType, and that is origin of its name. When you have some intersting ideas, and you can implement them in PT-OS. And I think it will reduce the waste of time.

I gave detailed comments in code and design ideas in /doc/ dir. And all of them is wrote in chinese.

PTOS target

These are the target that I want to do.

Multi-Core

• single Intel core (working)
• two same Intel cores (In the future)
• two Intel cores with different frequency (In the future)
• single Hbird e200 32 core (In the future)

There is a problems that the Hardware-Platform is based on Intel, and I want to transplant it to other platforms in the future. Recently I am building a SOC based on RISC-V ISA, so this maybe a new direction.

Memory Management

• physical page management (working)

  linux(Buddy system), book(bitmap ok)

• Fine-grained memory management (working)

  FreeRTOS(heap testing), Linux(Slab)

The detailed information about memory will be showed

Task Management

• ELF program load (tesing)
• Kernel thread (ok)
• Simple priority scheduling (ok)
• User process and thread (In the future)
• CFS scheduling (In the future, and it needs a long time)
• RR sechduling ((In the future, and it needs some time))
• EAS scheduling (In the future, and it needs a long time)

Interrupt and Timer Management

• Interrupt controler based on 8258A (ok)
• Timer based on 8253 (ok)

Debug and Error Handling

• Debug port
• Error Handling module

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Developing Environment

Platform and ToolChain

• Linuxmint 17.3/18.3
• GNU gcc 5.4
• GNU ld 2.26.1
• GNU Make 4.1
• bochs 2.6.9

If I build the RISC-V SOC successfully, and the "vivado" will be added in tools.

Compile Bochs

Fisrt step, you should download "bochs-2.6.9.tar.gz" from Bochs Website

Second step, you should install some package to solve dependency.

sudo apt-get install gcc g++ build-essential xorg-xdev
xserver-xorg-dev libgtk2.0-dev bochs-sdl

Third step, you should configure bochs in bochs_dir.

./configure --enable-debugger --enable-disasm --enable-iodebug
--enable-x86-debugger --with-x --with-x11

Final step, you should compile bochs in bochs_dir.

make -j4

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Source Code

bochs_conf: It includes the bochs's base configure file "bochsrc" and log file "bochsrc". When you use Makefile, a new bochsrc file will be created according to you pc's user name.

boot: It includes some boot code, such as the MBR and loader program.

build: The obj file and elf file will be built here.

dev: The device's hardware interface. (timer, disk_interface)

doc: Some design document which useful for understanding these code.

it: It includes some interrupt controler and some handling program.

kernel: It includes the code which are used to start all init and configure.

lib: There are some general program and struct, which is helpful for our development. (list, bitmap, heap, lock, elf, std_type_define)

mm_v1: This the simplest memory management system, which uses a bitmap to manage the physical/virtual memory's usage.(Low Level)

mm_v2: This the more complex memory management system, which uses a Buddy system to manage the physical memory's usage .(Middle Level)

sc: It has some system call. However, these function can only be used by kernel, because our OS is not completed. In the future , these sys_call will be occured by system_call handle function and interrupt.

Code Notice

The variable in code will be initialized by 0, and I add the option of -fno-zero-initialized-in-bss in gcc C_FLAGS. Therefore the variable will be put in .data segment.

User Notice

You should put "pt_os" dir and "bochs" dir in current user's Desktop, otherwise you need to modify "bochsrc" and "Makefile".

Book Reference

[1] 30天自己操作系统
[2] 操作系统真相还原
[3] linux内核完全注释
[4] 深入理解linux内核
[5] 深入理解linux内核架构
[6] 奔跑吧Linux内核
[7] 一个64位操作系统的设计与实现
[8] FreeRTOS源码详解与应用开发——基于STM32