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|
/*-------------------------------------------------------------------------+
| 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.rtems.com/license/LICENSE.
| **************************************************************************
|
| $Id$
+--------------------------------------------------------------------------*/
/*
* 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 <rtems/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
/*-------------------------------------------------------------------+
| Initialize the video because zero_bss has cleared initVideo parameters
| if it was called earlier
| So from now we can use printk
+-------------------------------------------------------------------*/
call _IBMPC_initVideo
/*---------------------------------------------------------------------+
| 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 <CR>\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
|
