diff options
Diffstat (limited to 'sysdeps/standalone/i386/force_cpu386/strtsupp.S')
| -rw-r--r-- | sysdeps/standalone/i386/force_cpu386/strtsupp.S | 89 |
1 files changed, 89 insertions, 0 deletions
diff --git a/sysdeps/standalone/i386/force_cpu386/strtsupp.S b/sysdeps/standalone/i386/force_cpu386/strtsupp.S new file mode 100644 index 0000000000..6b78a8c343 --- /dev/null +++ b/sysdeps/standalone/i386/force_cpu386/strtsupp.S @@ -0,0 +1,89 @@ +/* Copyright (C) 1994 Free Software Foundation, Inc. + Contributed by Joel Sherrill (jsherril@redstone-emh2.army.mil), + On-Line Applications Research Corporation. + +This file is part of the GNU C Library. + +The GNU C Library is free software; you can redistribute it and/or +modify it under the terms of the GNU Library General Public License as +published by the Free Software Foundation; either version 2 of the +License, or (at your option) any later version. + +The GNU C Library is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +Library General Public License for more details. + +You should have received a copy of the GNU Library General Public +License along with the GNU C Library; see the file COPYING.LIB. If +not, write to the Free Software Foundation, Inc., 675 Mass Ave, +Cambridge, MA 02139, USA. */ + +/* This file assists the board independent startup code by + * loading the proper segment register values. The values + * loaded are dependent on the FORCEBUG. + * + * NOTE: No stack has been established when this routine + * is invoked. It returns by jumping back to the start code. + * + */ + +/* + * FORCEBUG loads us into a virtual address space which + * really starts at PHYSICAL_ADDRESS_BASE. + * + */ + +.set PHYSICAL_ADDRESS_BASE, 0x00002000 + +/* + * At reset time, FORCEBUG normally has the segment selectors preloaded. + * If a human resets the instruction pointer, this will not have occurred. + * However, no guarantee can be made of the other registers if cs:ip was + * modified to restart the program. Because of this, the BSP reloads all + * segment registers (except cs) with the values they have following + * a reset. + */ + + +.set RESET_SS, 0x40 # initial value of stack segment register +.set RESET_DS, 0x40 # initial value of data segment register +.set RESET_ES, 0x40 # initial value of extra segment register +.set RESET_FS, 0x40 # initial value of "f" segment register +.set RESET_GS, 0x30 # initial value of "g" segment register + + +#define LOAD_SEGMENTS(_value,_segreg) \ + movw $_value##,%ax ; \ + movw %ax,##_segreg + + + .global _load_segments + + .global _establish_stack + +_load_segments: + + LOAD_SEGMENTS( RESET_SS, %ss ) + LOAD_SEGMENTS( RESET_DS, %ds ) + LOAD_SEGMENTS( RESET_ES, %es ) + LOAD_SEGMENTS( RESET_FS, %fs ) + LOAD_SEGMENTS( RESET_GS, %gs ) + + jmp _establish_stack # return to the bsp entry code + + .global _return_to_monitor +_return_to_monitor: + + movb $0,%al + int $0x20 # restart FORCEbug + jmp start # FORCEbug does not reset PC + + .data + + .global _Do_Load_IDT +_Do_Load_IDT: .byte 1 + + .global _Do_Load_GDT +_Do_Load_GDT: .byte 0 + |