Help regarding booting application processor

[Swapnil Pimpale]

Hi all,

 I am a final year engineering student and I am doing my project in
GRUB-1.97~beta4 and Linux Kernel 2.6.24.7.

 I am working on Intel Core 2 Duo architecture. I want to boot a
separate kernel on the second core.
 As of now, I have brought up the halted AP from the GRUB by sending
IPIs in the INIT-SIPI-SIPI sequence. I have also allocated a 4KB page
below 1MB and asked the AP to jump to that address.

 I am trying to put the BSP in while(1) loop and I want the AP to
switch from real to protected mode and then jump to start of kernel.
But whenever I do a jump to 1MB the system reboots.
 I am using the following code as the trampoline code for the AP.

 Can someone please let me know what is wrong in the following code.
 Awaiting your reply,

Thanks,
Swapnil Pimpale

----- trampoline.S -----
/* Tell GAS to generate 16-bit instructions so that this code works
          in real mode. */

#include <grub/symbol.h>
#include <grub/i386/pc/memory.h>


.align 4096
.code16
FUNCTION(TRAMPOLINE_CODE)
initial:

       mov     %cs, %ax
       mov     %ax, %ds
       cli

       lidtl   idtdesc - initial
       lgdtl   gdtdesc - initial

       mov $0x9e00, %bx                   // 9e00 is the cs
       shl $4, %ebx
       movl $(gdt - initial + 8), %eax
       movl %ebx, %eax

        mov $0x10, %bx
        xor %ecx, %ecx
        mov $0xb800, %cx                 // address of video RAM in %cx
        shl $4, %ecx
        mov $0x0744, %dx                 // for printing D
        xor %eax, %eax
        pushw %ax
        mov $0x08, %ax
        pushw %ax
        xor %eax, %eax
        mov $0x9e00, %ax
        shl $4, %eax
        add protcseg - initial, %eax
        pushl %eax

       xor %eax, %eax
       movl %cr0, %eax                 // turn on the PE bit
       orl $0x1, %eax
       movl %eax, %cr0

      jmp l1

l1:

 mov %bx, %ds
 mov %dx, (%ecx)                 // Print D
 add $2, %ecx
 add $1, %dx

 ADDR32 ljmpl $0x8,$((protcseg - initial) + (0x9e00 << 4))

 .align 256
 .code32
 protcseg:

l3:
 mov %dx, (%ecx)

 movw %bx, %es
 movw %bx, %fs
 movw %bx, %gs
 movw %bx, %ss

l4:
// The following is the code used by /loader/i386/linux.c for entering Linux
 mov $0x8c000, %esi
 xor %ebx, %ebx
 mov $0x8c000, %eax
 jmp *0x214(%eax)         // System reboots here

l5:
       jmp l5


.p2align 2
gdt:
       .word   0, 0
       .byte   0, 0, 0, 0

       .word   0xFFFF, 0
       .byte   0, 0x9A, 0xCF, 0

       .word   0xFFFF, 0
       .byte   0, 0x92, 0xCF, 0

       .word   0xFFFF, 0
       .byte   0, 0x9E, 0, 0

       .word   0xFFFF, 0
       .byte   0, 0x92, 0, 0

gdtdesc:
       .word   0x27
       .long   gdt

idtdesc:
       .word 0
       .long 0
FUNCTION(TRAMPOLINE_END)