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GDT

include/boot/gdt.h View source View on GitHub

Structs

Section titled “Structs”

gdt_entry

Section titled “gdt_entry”
struct gdt_entry (6 fields) source
§ uint16_t limit_low
§ uint16_t base_low
§ uint8_t base_middle
§ uint8_t access
§ uint8_t granularity
§ uint8_t base_high

gdt_ptr

Section titled “gdt_ptr”
struct gdt_ptr (2 fields) source
§ uint16_t limit
§ uint64_t base

gdt_entry_tss

Section titled “gdt_entry_tss”
struct gdt_entry_tss (8 fields) source
§ uint16_t limit_low
§ uint16_t base_low
§ uint8_t base_middle
§ uint8_t access
§ uint8_t granularity
§ uint8_t base_high
§ uint32_t base_upper
§ uint32_t reserved

Functions

Section titled “Functions”

gdt_load

Section titled “gdt_load”
void gdt_load(void)
source

Macros

Section titled “Macros”

ACCESS_CODE_RING0

Section titled “ACCESS_CODE_RING0”
#define ACCESS_CODE_RING0 0x9A
source

exec/read, ring 0

ACCESS_DATA_RING0

Section titled “ACCESS_DATA_RING0”
#define ACCESS_DATA_RING0 0x92
source

read/write, ring 0

ACCESS_CODE_RING3

Section titled “ACCESS_CODE_RING3”
#define ACCESS_CODE_RING3 0xFA
source

exec/read, ring 3

ACCESS_DATA_RING3

Section titled “ACCESS_DATA_RING3”
#define ACCESS_DATA_RING3 0xF2
source

read/write, ring 3

GRAN_CODE

Section titled “GRAN_CODE”
#define GRAN_CODE 0xAF
source

G=1, D/B=0, L=1, AVL=0

GRAN_DATA

Section titled “GRAN_DATA”
#define GRAN_DATA 0xAF
source

G=1, D/B=0, L=0, AVL=0

GDT_KERNEL_CODE

Section titled “GDT_KERNEL_CODE”
#define GDT_KERNEL_CODE 0x08
source

Kernel selectors (RPL = 0)

index 1

GDT_KERNEL_DATA

Section titled “GDT_KERNEL_DATA”
#define GDT_KERNEL_DATA 0x10
source

index 2

KERNEL_CS

Section titled “KERNEL_CS”
#define KERNEL_CS GDT_KERNEL_CODE
source

KERNEL_DS

Section titled “KERNEL_DS”
#define KERNEL_DS GDT_KERNEL_DATA
source

GDT_USER_CODE

Section titled “GDT_USER_CODE”
#define GDT_USER_CODE 0x28
source

User selectors (RPL = 3)

index 5 << 3

GDT_USER_DATA

Section titled “GDT_USER_DATA”
#define GDT_USER_DATA 0x30
source

index 6 << 3

USER_CS

Section titled “USER_CS”
#define USER_CS (GDT_USER_CODE | 0x3)
source

== 0x2B

USER_DS

Section titled “USER_DS”
#define USER_DS (GDT_USER_DATA | 0x3)
source

== 0x33

USER_SS

Section titled “USER_SS”
#define USER_SS USER_DS
source