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Diffstat (limited to 'c/src/lib/libbsp/i386/pc386/start/start.S')
| -rw-r--r-- | c/src/lib/libbsp/i386/pc386/start/start.S | 202 |
1 files changed, 202 insertions, 0 deletions
diff --git a/c/src/lib/libbsp/i386/pc386/start/start.S b/c/src/lib/libbsp/i386/pc386/start/start.S new file mode 100644 index 0000000000..323aa3d088 --- /dev/null +++ b/c/src/lib/libbsp/i386/pc386/start/start.S @@ -0,0 +1,202 @@ +/*-------------------------------------------------------------------------+ +| 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) 1989-1998. +| * On-Line Applications Research Corporation (OAR). +| * Copyright assigned to U.S. Government, 1994. +| * +| * 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. +| ************************************************************************** +| +| $Id$ ++--------------------------------------------------------------------------*/ + +/* + * 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 <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 + + + + |