LC

Set Up the Interrupt Descriptor Table in Protected Mode

hard3/8

Build a Flat GDT for Protected Mode Enable Basic Paging in Protected Mode

Language

Compiler

2.0s Limit 256MB

Implementation

Why This Matters

Linux's arch/x86/kernel/idt.c and every hobby kernel on the OSDev wiki build exactly this 256-entry, 8-byte-descriptor IDT with interrupt gates for hardware IRQs and trap/interrupt gates for exceptions and syscalls (historically INT 0x80 on Linux). A missing or malformed entry for divide-by-zero or page-fault (vector 14) is what turns a recoverable exception into an unrecoverable triple-fault reboot.

Hints

0 / 3 revealed

Validation Suite

main.c

Workspace 1.0

Implement IDT setup for protected mode in C.

Requirements:

Define IDT entry structure (8 bytes)
Implement encode_idt_entry(offset, selector, access)
Create handlers for: divide by zero (0), timer (32), keyboard (33), syscall (128)
Implement load_idt() that simulates lidt
Print IDT entry details (offset, selector, access, type)
Show interrupt gate vs trap gate difference
Show DPL levels
Implement handle_interrupt() dispatcher
Show EOI being sent for hardware interrupts

Test:

Show IDT loaded
Show handlers registered
Show divide by zero handler
Show timer handler
Show syscall handler