void init_gdt()
{
//Sets up the gdt pointer
gdtp.limit = (sizeof(struct gdt_entry)*GDT_LEN)-1;
gdtp.base = (unsigned int)&gdt_table;
/*the first NULL entry*/
gdt_set_gate(0, 0,0,0,0);
// 0x9A, 0x92, 0xFA, 0xF2
gdt_set_gate(1, 0, 0xFFFFFFFF, 0x9A, 0xCF);
gdt_set_gate(2, 0, 0xFFFFFFFF, 0x92, 0xCF);
gdt_set_gate(3, 0, 0xFFFFFFFF, 0xFA, 0xCF);
gdt_set_gate(4, 0, 0xFFFFFFFF, 0xF2, 0xCF);
// Ok, add the tss
set_tss(5, 0x10, 0x0);
/*actually flushes gdt with lgdt code*/
gdt_flush((unsigned int)&gdtp);
// now flush the TSS
tss_flush();
}
void
init_segment(void) {
memset(gdt, 0, sizeof(gdt));
set_segment(&gdt[SEG_KERNEL_CODE], DPL_KERNEL, SEG_EXECUTABLE | SEG_READABLE);
set_segment(&gdt[SEG_KERNEL_DATA], DPL_KERNEL, SEG_WRITABLE );
set_segment(&gdt[SEG_USER_CODE], DPL_USER, SEG_EXECUTABLE | SEG_READABLE);
set_segment(&gdt[SEG_USER_DATA], DPL_USER, SEG_WRITABLE );
write_gdtr(gdt, sizeof(gdt));
set_tss(&gdt[SEG_TSS]);
write_tr( SELECTOR_USER(SEG_TSS) );
}
void init_sched (void)
{
unsigned long eflags;
eflags = read_flags ();
if ((idle_task = kmalloc (sizeof (Task), 0)) == NULL) {
printk ("init_sched: not enough memory\n");
write_flags (eflags);
return;
}
idle_task->pid = next_pid++;
idle_task->next = idle_task;
#if 0
idle_task->kernel_stack = kstack;
#endif
idle_task->tss.link = 0;
idle_task->tss.esp0 = (unsigned long) &kstack[PAGE_SIZE >> 2];
idle_task->tss.ss0 = KERNEL_DS;
idle_task->tss.cr3 = (unsigned long) &pg_dir[0];
idle_task->tss.es = KERNEL_DS;
idle_task->tss.cs = KERNEL_CS;
idle_task->tss.ss = KERNEL_DS;
idle_task->tss.ds = KERNEL_DS;
idle_task->tss.fs = KERNEL_DS;
idle_task->tss.gs = KERNEL_DS;
current = idle_task;
set_tss (idle_task);
write_tr (idle_task->tss.tr);
cli ();
register_interrupt (0x08, do_timer);
register_interrupt (0x80, do_fork);
outb(0x36,0x43);
outb(0xa9,0x40);
outb(0x04,0x40);
write_flags (eflags);
}
static inline void flush_tss()
{
uint32_t base = (uint32_t)&tss;
gdt_install_tss(base, base + sizeof(tss));
set_tss(TSS_SELECTOR);
}
