yyu / osfs00

Operating System From Scratch : learn OS by practice

Operating System From Scratch

This is not one project. This is a project series. Following these steps, you'll see how to write your own Operating System from scratch:

• Step 01: A smallest "OS"
• Step 02: Setup the development environment
• Step 03: x86 Protect Mode
• Step 04: Boot loader
• Step 05: Kernel
• Step 06: Process
• Step 07: TTYs
• Step 08: IPC
• Step 09: File System
• Step 10: Memory Management
• Step 11: Learn with fun

There are many ways to learn OS, but I believe the best way is to learn by practice. There are many open source OS code, but the code bases are huge. You will get lost in the source code labyrinth.

There are good books, Operating System: Design and Implementation by A.S. Tanenbaum and A.S. Woodhull for example, but they don't teach you where to begin either.

That's why you should come here. If Tanenbaum's book is a reference, my project series is a tutorial. Prof. Tanenbaum tells you what. I'll tell you how.

Click here to begin your OS journey.

osfs00's Issues

the code of chapter9/b has running error

Run the code of chapter9/b, you will find the tty print the follow message:

Exception! --> #UD Invalid Opcode (Undefined Opcode)

EFLAGS:0x11202CS:0x5EIP:0x34976

BaseAddrL BaseAddrH LengthLow LengthHigh Type
00000000h 00000000h 0009FC00h 00000000h 00000001h
0009FC00h 00000000h 00000400h 00000000h 00000002h
000E8000h 00000000h 00018000h 00000000h 00000002h
00100000h 00000000h 01EF0000h 00000000h 00000001h
01FF0000h 00000000h 00010000h 00000000h 00000003h
FFFC0000h 00000000h 00040000h 00000000h 00000002h

RAM size:01FF0000h
-----"cstart" begins-----
-----"cstart" finished-----
-----"kernel_main" begins-----
NrDrives:1.
Task FS begins.

But the right message should be like this:

Booting ............
Ready.

Loading ......................................................................
Ready.

BaseAddrL BaseAddrH LengthLow LengthHigh Type
00000000h 00000000h 0009FC00h 00000000h 00000001h
0009FC00h 00000000h 00000400h 00000000h 00000002h
000E8000h 00000000h 00018000h 00000000h 00000002h
00100000h 00000000h 01EF0000h 00000000h 00000001h
01FF0000h 00000000h 00010000h 00000000h 00000003h
FFFC0000h 00000000h 00040000h 00000000h 00000002h

RAM size:01FF0000h
-----"cstart" begins-----
-----"cstart" finished-----
-----"kernel_main" begins-----
NrDrives:1.
Task FS begins.
HD SN: BXHD00011
HD Model: Generic 1234
LBA supported: Yes
LBA48 supported: Yes
HD size: 83MB
PART_0: base 0(0x0), size 163296(0x27DE0) (in sector)
PART_1: base 63(0x3F), size 20097(0x4E81) (in sector)
PART_2: base 20160(0x4EC0), size 143136(0x22F20) (in sector)
PART_3: base 0(0x0), size 0(0x0) (in sector)
PART_4: base 0(0x0), size 0(0x0) (in sector)
16: base 20223(0x4EFF), size 40257(0x9D41) (in sector)
17: base 60543(0xEC7F), size 30177(0x75E1) (in sector)
18: base 90783(0x1629F), size 42273(0xA521) (in sector)
19: base 133119(0x207FF), size 28161(0x6E01) (in sector)
20: base 161343(0x2763F), size 1953(0x7A1) (in sector)

spinning in FS ...

Then I located the error, hd.c is the hard disk driver program.
task_hd() is the main loop of HD driver, it invoke the init_hd() to initialize the hard disk where will print NrDrives: 1.
After the init_hd() finished, instructions will come to hd_open(), then I go into the hd_open(). Before the "int drive = DRV_OF_DEV(device)", I put printl(), it works. But after the "int drive = DRV_OF_DEV(device)", I put printl(), it didn't work. So the location of error is here.
As you can see, DRV_OF_DEV(device) is a macro define, if the value of device is 0x20, the result of DRV_OF_DEV(0x20) will be 0. Then I replace the device with 0x20, the program runs well. It's odd, isn't it?
If I modify the DRV_OF_DEV(dev) like this:

define DRV_OF_DEV(dev) (dev <= MAX_PRIM ? dev / NR_PRIM_PER_DRIVE : (dev - MINOR_hd1a) / (NR_SUB_PER_DRIVE - 1))

the program runs well.The same condition lies in the chapter9/c, chapter9/d ...

After modified this bug, a new error happened in chapter9/d, tty print message like this:
Booting ............
Ready.

Loading ......................................................................
Ready.

BaseAddrL BaseAddrH LengthLow LengthHigh Type
00000000h 00000000h 0009FC00h 00000000h 00000001h
0009FC00h 00000000h 00000400h 00000000h 00000002h
000E8000h 00000000h 00018000h 00000000h 00000002h
00100000h 00000000h 01EF0000h 00000000h 00000001h
01FF0000h 00000000h 00010000h 00000000h 00000003h
FFFC0000h 00000000h 00040000h 00000000h 00000002h

RAM size:01FF0000h
-----"cstart" begins-----
-----"cstart" finished-----
-----"kernel_main" begins-----
NrDrives:1.
Task FS begins.
HD SN: BXHD00011
HD Model: Generic 1234
LBA supported: Yes
LBA48 supported: Yes
HD size: 83MB
PART_0: base 0(0x0), size 163296(0x27DE0) (in sector)
PART_1: base 63(0x3F), size 20097(0x4E81) (in sector)
PART_2: base 20160(0x4EC0), size 143136(0x22F20) (in sector)
PART_3: base 0(0x0), size 0(0x0) (in sector)
PART_4: base 0(0x0), size 0(0x0) (in sector)
16: base 20223(0x4EFF), size 40257(0x9D41) (in sector)
17: base 60543(0xEC7F), size 30177(0x75E1) (in sector)
18: base 90783(0x1629F), size 42273(0xA521) (in sector)
19: base 133119(0x207FF), size 28161(0x6E01) (in sector)
20: base 161343(0x2763F), size 1953(0x7A1) (in sector)
dev size: 0x9D41 sectors
But the right message should be like this:
Booting ............
Ready.

Loading ......................................................................
Ready.

BaseAddrL BaseAddrH LengthLow LengthHigh Type
00000000h 00000000h 0009FC00h 00000000h 00000001h
0009FC00h 00000000h 00000400h 00000000h 00000002h
000E8000h 00000000h 00018000h 00000000h 00000002h
00100000h 00000000h 01EF0000h 00000000h 00000001h
01FF0000h 00000000h 00010000h 00000000h 00000003h
FFFC0000h 00000000h 00040000h 00000000h 00000002h

RAM size:01FF0000h
-----"cstart" begins-----
-----"cstart" finished-----
-----"kernel_main" begins-----
NrDrives:1.
Task FS begins.
HD SN: BXHD00011
HD Model: Generic 1234
LBA supported: Yes
LBA48 supported: Yes
HD size: 83MB
PART_0: base 0(0x0), size 163296(0x27DE0) (in sector)
PART_1: base 63(0x3F), size 20097(0x4E81) (in sector)
PART_2: base 20160(0x4EC0), size 143136(0x22F20) (in sector)
PART_3: base 0(0x0), size 0(0x0) (in sector)
PART_4: base 0(0x0), size 0(0x0) (in sector)
16: base 20223(0x4EFF), size 40257(0x9D41) (in sector)
17: base 60543(0xEC7F), size 30177(0x75E1) (in sector)
18: base 90783(0x1629F), size 42273(0xA521) (in sector)
19: base 133119(0x207FF), size 28161(0x6E01) (in sector)
20: base 161343(0x2763F), size 1953(0x7A1) (in sector)
dev size: 0x9D41 sectors devbase:0x9DFE00, sb:0x9E0000, imap:0x9E0200, smap:0x9E0400
inodes:0x9E1800, 1st_sector:0xA01800
spinning in FS ...

This time I locate the error from chapter9/d/fs/main.c, in this file you will see task_fs() is the main loop of TASK FS, In the task_fs(), it invokes init_fs(). In the init_fs(), it invokes send_recv(BOTH, dd_map[MAJOR(ROOT_DEV)].driver, &driver_msg). In the send_recv(), it invokes sendrec(). In the sendrec(), it invokes sys_sendrec(). In the sys_sendrec(), it invokes msg_receive(). msg_receive() is the last function which be invoked, and it returns 0. After msg_receive() has returned, the sys_sendrec() return. But after sys_sendrec() return, sendrec() didn't return, I don't know why.
I want to know why the program stop in the sendrec() function and it cannot return.

关于章节4 bootloader 的问题

.../chapter4/c/boot.asm
这里面加载loader前 bootloader 自身能不能先移动自身到其他位置
然后跳转到其他位置继续执行,最后完成加载loader的任务?
比如 将bootloader从 0x7c00h 移动到 0x0600h
长跳转到0x0600h 之后
再将loader 加载并覆盖到 0x7c00h的位置
最后长跳转到0x7c00h 开始执行loader的代码

2023年了，该书籍是否有出第三版的计划？

于老师你好，想问下，现在《Orange'S:一个操作系统的实现》这本书有没有出第三版的计划？

于老师好！这个问题不重要，不问了

祝好！

the code of chapter9/b have running error

run the code of chapter9/b, you will find the tty print the follow message.

Exception! --> #UD Invalid Opcode (Undefined Opcode)

EFLAGS:0x11202CS:0x5EIP:0x34976

BaseAddrL BaseAddrH LengthLow LengthHigh Type
00000000h 00000000h 0009FC00h 00000000h 00000001h
0009FC00h 00000000h 00000400h 00000000h 00000002h
000E8000h 00000000h 00018000h 00000000h 00000002h
00100000h 00000000h 01EF0000h 00000000h 00000001h
01FF0000h 00000000h 00010000h 00000000h 00000003h
FFFC0000h 00000000h 00040000h 00000000h 00000002h

RAM size:01FF0000h
-----"cstart" begins-----
-----"cstart" finished-----
-----"kernel_main" begins-----
NrDrives:1.
Task FS begins.

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