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static void init_gdt()
{
   gdt_pointer.limit = (sizeof(struct gdt_entry) * 5) - 1;
   gdt_pointer.base  = (u32int)&gdt_entries;

   gdt_set_gate(0, 0, 0, 0, 0);                // Null segment
   gdt_set_gate(1, 0, 0xFFFFFFFF, 0x9A, 0xCF); // Code segment
   gdt_set_gate(2, 0, 0xFFFFFFFF, 0x92, 0xCF); // Data segment
   gdt_set_gate(3, 0, 0xFFFFFFFF, 0xFA, 0xCF); // User mode code segment
   gdt_set_gate(4, 0, 0xFFFFFFFF, 0xF2, 0xCF); // User mode data segment
   write_tss(5, 0x10, 0);

   gdt_flush((u32int)&gdt_pointer);
   tss_flush();
   failure("Force stop after TSS load");
};

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static void write_tss(s32int num, u16int ss0, u32int esp0)
{
   u32int base = (u32int) &tss;
   u32int limit = base + sizeof(struct tss_entry);

   gdt_set_gate(num, base, limit, 0xE9, 0x00);

   memset(&tss, 0, sizeof(struct tss_entry));

   tss.ss0  = ss0;
   tss.esp0 = esp0;
}

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[GLOBAL tss_flush]
tss_flush:
  mov ax, 0x2B ; TSS index
  ltr ax
  ret

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struct tss_entry
{
	u32int link;        // Unused
	u32int esp0;        // Kernel stack pointer (loaded on task-switch)
	u32int ss0;         // Kernel stack segment (0x10, u32int to avoid the resv. 16-bit high word)
	u32int esp1;        // Unused....
	u32int ss1;
	u32int esp2;
	u32int ss2;
	u32int cr3;
	u32int eip;
	u32int eflags;
	u32int eax;
	u32int ecx;
	u32int edx;
	u32int ebx;
	u32int esp;
	u32int ebp;
	u32int esi;
	u32int edi;
	u32int es;
	u32int cs;
	u32int ss;
	u32int ds;
	u32int fs;
	u32int gs;
	u32int ldtr;
	u16int iopb;        // Please do not use this value, because no programs will have access to I/O ports directly
	u16int resv;
} __attribute__ ((packed));