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/* bspclean.c
*
* These routines return control to 167Bug after a normal exit from the
* application.
*
* 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.
*
* Modifications of respective RTEMS files:
* Copyright (c) 1998, National Research Council of Canada
*
* $Id$
*/
#include <rtems.h>
#include <bsp.h>
#include <page_table.h>
/*
* bsp_return_to_monitor_trap
*
* Switch the VBR back to ROM and make a .RETURN syscall to return control to
* 167 Bug. If 167Bug ever returns, restart the application.
*
* Input parameters: NONE
*
* Output parameters: NONE
*
* Return values: NONE
*/
static void bsp_return_to_monitor_trap( void )
{
extern void start( void );
register volatile void *start_addr;
page_table_teardown();
lcsr->intr_ena = 0; /* disable interrupts */
m68k_set_vbr(0xFFE00000); /* restore 167Bug vectors */
asm volatile( "trap #15 /* trap to 167Bug */
.short 0x63" ); /* return to 167Bug (.RETURN) */
/* restart program */
start_addr = start;
asm volatile( "jmp %0@" : "=a" (start_addr) : "0" (start_addr) );
}
/*
* bsp_cleanup
*
* This code was copied from other MC680x0 MVME BSPs.
* Our guess is that someone was concerned about the CPU no longer being in
* supervisor mode when they got here. This function forces the CPU back to
* supervisor mode so the VBR may be changed. It places the address of the
* function that makes a 167Bug .RETURN syscall in the trap 13 entry in the
* exception vector, and then issues a trap 13 call. It is also possible that
* the code was copied from some other OS that does run tasks in user mode.
* In any case, it appears to be a bit of paranoia, and could lead to
* problems if 167Bug is invoked before we get to switch the VBR back to
* 167Bug because trap 13 is documented as being reserved for the internal
* use of the debugger.
*
* Prototyped in rtems/c/src/lib/libbsp/m68k/mvme167/include/bsp.h
*
* Input parameters: NONE
*
* Output parameters: NONE
*
* Return values: DOES NOT RETURN
*/
void bsp_cleanup( void )
{
M68Kvec[ 45 ] = bsp_return_to_monitor_trap;
asm volatile( "trap #13" );
}
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