Triple Fault on Far Jump To Long Mode

K3achas · **Joined:** Sat May 26, 2018 5:32 pm **Posts:** 22

Whenever I run the following code to switch to long mode in qemu, it triple faults (by way of #GP). I've tried changing the GDT entry for the code segment, but I haven't had success so far. Any ideas would be much appreciated.

Links to file for the code to switch from the 32-bit environment grub loads the bootstrapper in to 64-bit long mode (fault is on the far jump), the gdt, and the overall repository.

OmeletHopper · **Joined:** Mon Jun 04, 2018 6:37 am **Posts:** 4

This (most likely) won't fix your triple fault, but just a quick look at your early.asm and I noticed you've labeled (and set up) your stack backwards. Remember: On x86 The stack grows downwards. From the wiki:

Code:

   To set up a stack, we set the esp register to point to the top of our
   stack (as it grows downwards on x86 systems). This is necessarily done
   in assembly as languages such as C cannot function without a stack.

Although written for 32 bit protected mode, it should apply to you. I could also be completely wrong, because I am new to OSDev, but being proven wrong is an opportunity to learn

EDIT: Sorry, I goofed. I misread your code and had a dyslexic moment. Your stack is set up properly.

iansjack · **Posted:** Mon Jun 04, 2018 8:17 am

1. Perhaps I'm missing something, but I couldn't see a long jump in your code.

2. You don't appear to set up a page table.

OSDev.org

Triple Fault on Far Jump To Long Mode

Who is online