Question

I work on Atom-32bit-intel, I have to port MicroC OS II, so there is no code to make any configuration on the Atom (No GDT, no LDT…):

my question is more about the state of the Atom-32bit after a reset, is the Atom in protecte mode or not ? and the most important how do i check which mode is it (which registers have to be checked nad how)?

Remark:
The CR0.PE = 1 (I checked it), is that enough to prove that the Atom is in protected mode ?

************ UPDATE : *****************

    /*Read the IDTR*/
    sidt (idt_ptr)

    /*Read the GDTR*/
    sgdt (gdt_ptr)

So I tried just to use IDT’s address to link my ISR to the IDT :

fill_interrupt(ISR_Nbr,(unsigned int) isr33, 0x08, 0x8E);

static void fill_interrupt(unsigned char num, unsigned int base, unsigned short sel, unsigned char flags)
{
    unsigned short *Interrupt_Address;

    /*address = idt_ptr.base + num * 8 byte*/
    Interrupt_Address = (unsigned short *)(idt_ptr.base + num*8);

    *(Interrupt_Address) = base&0xFFFF;
    *(Interrupt_Address+1) = sel;
    *(Interrupt_Address+1) = (flags>>8)&0xFF00;
    *(Interrupt_Address+1) = (base>>16)&0xFFFF;

}

my ISR a imple one :

isr33:
nop
nop
cli
push %ebp   //save the context to swith back
mov %esp,%ebp




pop %ebp //Return to the calling function
sti
ret

Answer 1

Resolved, I use N450 Atom board, it has already a BIOS, the BIOS configures the board in Protected Mode.