my gdt is initialized correctly in 0x7cec and with size 0x17 which all sounds correct (24 bytes for null+code+data segment descriptors) and for some reason the idt part of the qemu int log shows:
IDT= 50000000 000007ff
I have no idea why it says its initialized to 0x50000000 although my size seems correct (7ff=256*8 which is the size i wanted).
Code: Select all
#include "memory.h"
#include "screen.h"
#include "isrs.h"
#include "idt.h"
#include <stdint.h>
/* Defines an IDT entry */
typedef struct {
uint16_t isr_low; // The lower 16 bits of the ISR's address
uint16_t kernel_cs; // The GDT segment selector that the CPU will load into CS before calling the ISR
uint8_t reserved; // Set to zero
uint8_t attributes; // Type and attributes; see the IDT page
uint16_t isr_high; // The higher 16 bits of the ISR's address
} __attribute__((packed)) idt_entry_t;
typedef struct {
uint16_t limit;
uint32_t base;
} __attribute__((packed)) idtr_t;
__attribute__((aligned(0x10)))
idt_entry_t idt[IDT_MAX_DESCRIPTORS]; // Create an array of IDT entries; aligned for performance
idtr_t idtr;
void idt_set_gate(uint8_t vector, void* isr, uint8_t flags) {
idt_entry_t* descriptor = &idt[vector];
descriptor->isr_low = (uint32_t)isr & 0xFFFF;
descriptor->kernel_cs = 0x08; // offset of code segment descriptor in the GDT
descriptor->attributes = flags;
descriptor->isr_high = (uint32_t)isr >> 16;
descriptor->reserved = 0;
}
void idt_install(void);
/* Installs the IDT */
void idt_install()
{
/* Sets the special IDT pointer up */
idtr.limit = (uint16_t)sizeof(idt_entry_t) * IDT_MAX_DESCRIPTORS - 1;
idtr.base = (uintptr_t)&idt[0];
/* Clear out the entire IDT, initializing it to zeros */
memset((unsigned char *)&idt, 0, sizeof(idt_entry_t) * IDT_MAX_DESCRIPTORS);
/* Add any new ISRs to the IDT here using idt_set_gate */
isrs_install();
__asm__ __volatile__ ("lidt %0" : : "m"(idtr)); // load the new IDT
__asm__ __volatile__ ("sti"); // load the new IDT
}
Does someone have any idea to what is causing the gp?
