Subversion Repositories openrisc_2011-10-31

/*-------------------------------------------------------------------------+

| start.s v1.1 - PC386 BSP - 1997/08/07

+--------------------------------------------------------------------------+

| This file contains the entry point for the application.

| The name of this entry point is compiler dependent.

| It jumps to the BSP which is responsible for performing all initialization.

+--------------------------------------------------------------------------+

| (C) Copyright 1997 -

| - NavIST Group - Real-Time Distributed Systems and Industrial Automation

|

| http://pandora.ist.utl.pt

|

| Instituto Superior Tecnico * Lisboa * PORTUGAL

+--------------------------------------------------------------------------+

| Modified the 20/05/1998  by valette@crf.canon.fr in order to give a working

| example of eraly stage debugging via the DEBUG_EARLY_START define.

+--------------------------------------------------------------------------+

| Disclaimer:

|

| This file is provided "AS IS" without warranty of any kind, either

| expressed or implied.

+--------------------------------------------------------------------------+

| This code is based on an earlier generation RTEMS i386 start.s and the

| following copyright applies:

|

| **************************************************************************

| *  COPYRIGHT (c) 1989-1999.

| *  On-Line Applications Research Corporation (OAR).

| *

| *  The license and distribution terms for this file may be

| *  found in the file LICENSE in this distribution or at

| *  http://www.OARcorp.com/rtems/license.html.

| **************************************************************************

|

|  $Id: start.S,v 1.2 2001-09-27 11:59:48 chris Exp $

+--------------------------------------------------------------------------*/

/*

 * The most trivial start.s possible. It does not know anything

 * about system it is running on, so it will jump to appropriate

 * place in BSP specific place to do things it knows nothing about

 */

#include "asm.h"

/*----------------------------------------------------------------------------+

| Size of heap and stack:

+----------------------------------------------------------------------------*/

.set STACK_SIZE, 0x1000

/*----------------------------------------------------------------------------+

| CODE section

+----------------------------------------------------------------------------*/

BEGIN_CODE

        PUBLIC (start)          # GNU default entry point

        EXTERN (boot_card)

        EXTERN (_load_segments)

        EXTERN (_return_to_monitor)

        EXTERN (_IBMPC_initVideo)

        EXTERN (debugPollingGetChar)

        EXTERN (checkCPUtypeSetCr0)

/*

 * In case this crashes on your machine and this is not due

 * to video mode set by the loader, you may try to define

 * the following variable:

 */

/* #define DEBUG_EARLY_START */

SYM (start):

        /*

         *  When things are really, REALLY!, bad -- turn on the speaker and

         *  lock up.  This shows whether or not we make it to a certain

         *  location.

         */

#if 0

        inb     $0x61, al

        orb     $0x03, al

        outb    al, $0x61       # enable the speaker

speakl: jmp     speakl             # and SPIN!!!

#endif

        nop

        cli                     # DISABLE INTERRUPTS!!!

        cld

#ifdef DEBUG_EARLY_START

        /*

         * Must get video attribute to have a working printk.

         * Note that the following code assume we already have

         * valid segments and a stack. It should be true for

         * any loader starting RTEMS in protected mode (or

         * at least I hope so : -)).

         */

        call _IBMPC_initVideo

        /*

         * try printk and a getchar in polling mode ASAP

         */

        pushl   $welcome_msg

        call    printk

        addl    $4, esp

        /* call debugPollingGetChar */

#endif

/*----------------------------------------------------------------------------+

| Load the segment registers (this is done by the board's BSP) and perform any

| other board specific initialization procedures, this piece of code

| does not know anything about

|

| NOTE: Upon return, gs will contain the segment descriptor for a segment which

|       maps directly to all of physical memory.

+----------------------------------------------------------------------------*/

        jmp     SYM (_load_segments)    # load board dependent segments

/*----------------------------------------------------------------------------+

| Set up the stack

+----------------------------------------------------------------------------*/

        PUBLIC (_establish_stack)

SYM (_establish_stack):

        movl    $_end, eax              # eax = end of bss/start of heap

        addl    $STACK_SIZE, eax        # make room for stack

        andl    $0xffffffc0, eax        # align it on 16 byte boundary

        movl    eax, esp                # set stack pointer

        movl    eax, ebp                # set base pointer

/*----------------------------------------------------------------------------+

| Zero out the BSS segment

+----------------------------------------------------------------------------*/

SYM (zero_bss):

        cld                             # make direction flag count up

        movl    $ SYM (_end), ecx       # find end of .bss

        movl    $ SYM (_bss_start), edi # edi = beginning of .bss

        subl    edi, ecx                # ecx = size of .bss in bytes

        shrl    ecx                     # size of .bss in longs

        shrl    ecx

        xorl    eax, eax                # value to clear out memory

        repne                           # while ecx != 0

        stosl                           #   clear a long in the bss

/*---------------------------------------------------------------------+

| Check CPU type. Enable Cache and init coprocessor if needed.

+---------------------------------------------------------------------*/

        call checkCPUtypeSetCr0

/*---------------------------------------------------------------------+

| Transfer control to User's Board Support Package

+---------------------------------------------------------------------*/

        pushl   $0                      # environp

        pushl   $0                      # argv

        pushl   $0                      # argc

        call    SYM (boot_card)

        addl    $12, esp

/*---------------------------------------------------------------------+

| Clean up - we do not know anything about it, so we will

| jump to BSP specific code to do cleanup

+---------------------------------------------------------------------*/

        jmp     SYM (_return_to_monitor)

END_CODE

BEGIN_DATA

        PUBLIC(_stack_size)

SYM(_stack_size):

        .long STACK_SIZE

#ifdef DEBUG_EARLY_START

        PUBLIC (welcome_msg)

SYM (welcome_msg) :

        .string "Ready to debug RTEMS ?\nEnter \n"

        PUBLIC (hex_msg)

SYM (hex_msg) :

        .string "0x%x\n"

        PUBLIC (made_it_msg)

SYM (made_it_msg) :

        .string "made it to %d\n"

#endif

END_DATA

END