Jmp does not work in protected mode

[gabemaiberger]

Hello, the jmp opcode does not work in protected mode in the file kernel.asm. I think I loaded my gdt correctly. Can anybody help me?

[Nessphoro]

Not sure if you're trolling or not.

Code: Select all

start:
jmp start

[iansjack]

As always, single-step through the code in a debugger. These sort of errors are trivial and give you good experience of debugging for when you get on to the difficult stuff.

[gabemaiberger]

Where can I get a single step debugger?

[iansjack]

Difficult to say, since I don't know what Operating System you are running on or what toolset you are using.

I use Linux with the GNU toolset and GCC. The most common debugger there is gdb which you can use in conjunction with qemu. I use a GUI front end called ddd which makes life slightly simpler. Or you can use an emulator with a debugger built in. I don't use Bochs but I understand that provides debugging facilities. I am a fan of SimNow from AMD, which provides a very convenient interface for debugging the early stages of an OS. Unfortunately this is now only available for Linux.

You may be developing on another OS. In that case you are going to have to search out your own debugger (although I believe the GNU toolset is also available on Windows). Whatever, I strongly recommend that you find a debugger that suits you and learn how to use it. Unless you are a genius at just looking at code, or memory dumps, and seeing what is wrong you will find OS development very difficult without debugging facilities.

You could even just search through these forums. The sort of question that you ask has been asked many times before; indeed there is another running thread currently on an almost identical issue. You will be extremely fortunate if you can persuade people to review your code to find your mistakes for you.

[Kazinsal]

Not sure if you're trolling or not.

Code: Select all

start:
jmp start

I have no words.

[Mikemk]

Not sure if you're trolling or not.

Code: Select all

start:
jmp start

I have no words.

yeah, I knew better than that when I started