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fix: gdt work I think

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starnakin
2024-09-10 21:36:28 +02:00
parent bc99b99c82
commit 365ed0cc2e
4 changed files with 80 additions and 73 deletions
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41
headers/gdt.h
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@ -2,16 +2,19 @@
#include <stdint.h>
#define GDT_BASE 0x00000800
// sizeof(Segment Descriptor) * nb(Segment Descriptor)
#define GDT_SIZE 8 * 7
#define GDT_ADDRESS 0x00000800
#define GDT_SIZE 7
struct gdt_entry {
uint32_t limit;
uint32_t base;
uint8_t access_byte;
uint8_t flags;
};
// https://wiki.osdev.org/Global_Descriptor_Table#Segment_Descriptor
struct gdt_entry
{
uint16_t limit_low;
uint16_t base_low;
uint8_t base_middle;
uint8_t access;
uint8_t limit_high_and_flags;
uint8_t base_high;
} __attribute__((packed)) ;
// https://wiki.osdev.org/Global_Descriptor_Table#GDTR
struct gdt_descriptor {
@ -19,4 +22,22 @@ struct gdt_descriptor {
uint32_t base;
} __attribute__((packed));
void initGdt();
void initGdt();
#define GDT_FLAG_64BIT_MODE 0b0010
#define GDT_FLAG_32BIT_MODE 0b0100
#define GDT_FLAG_PAGE_MODE 0b1000
#define GDT_FLAG_BYTE_MODE 0b1000
#define GDT_ACCESS_P_VALID 0b10000000
#define GDT_ACCESS_DPL_KERNEL_MODE 0b00000000
#define GDT_ACCESS_DPL_USER_MODE 0b01100000
#define GDT_ACCESS_S_CODE_OR_DATA 0b00010000
#define GDT_ACCESS_S_SYSTEM_SEGMENT 0b00010000
#define GDT_ACCESS_E_EXECUTABLE 0b00001000
#define GDT_ACCESS_E_NOT_EXECUTABLE 0b00000000
#define GDT_ACCESS_DC_CONFORM 0b00000100 // TODO UNDERSTAND THIS BIT
#define GDT_ACCESS_DC_NOT_CONFORM 0b00000000
#define GDT_ACCESS_RW_READABLE_FOR_CODE_WRITABLE_FOR_DATA 0b00000010
#define GDT_ACCESS_A_ACCESSED 0b00000001
#define GDT_ACCESS_A_NOT_ACCESSED 0b00000000