root/core/init.inc

; -*- fundamental -*-
; -----------------------------------------------------------------------
;
;   Copyright 2004-2008 H. Peter Anvin - All Rights Reserved
;   Copyright 2009 Intel Corporation; author: H. Peter Anvin
;
;   This program is free software; you can redistribute it and/or modify
;   it under the terms of the GNU General Public License as published by
;   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
;   Boston MA 02111-1307, USA; either version 2 of the License, or
;   (at your option) any later version; incorporated herein by reference.
;
; -----------------------------------------------------------------------

;
; init.inc
;
; Common initialization code (inline)
;

                section .text16
common_init:
                ; Initialize PM invocation framework
                call pm_init

                ; Decompress PM code to its target location
                pm_call pm_decompress
                cmp eax,__pm_code_len
                jne kaboom

;
; Initialize timer
;
                call timer_init

;
; Initialize configuration information
;
                call reset_config

;
; Set up the COMBOOT APIs
;
                call comboot_setup_api

;
; Now set up screen parameters
;
                call adjust_screen

;
; CPU-dependent initialization and related checks.
;
check_escapes:
                mov ah,02h                      ; Check keyboard flags
                int 16h
                mov [KbdFlags],al               ; Save for boot prompt check
                test al,04h                     ; Ctrl->skip 386 check
                jnz skip_checks

;
; Now check that there is sufficient low (DOS) memory
;
; NOTE: Linux doesn't use all of real_mode_seg, but we use the same
; segment for COMBOOT images, which can use all 64K
;
                int 12h
                mov edx,__lowmem_heap + min_lowmem_heap + 1023
                shr edx,10
                cmp ax,dx
                jae enough_ram
                mov si,err_noram
                mov cl,10
                push dx
                div cl
                add [si+err_noram.need-err_noram+2],ah
                cbw
                div cl
                add [si+err_noram.need-err_noram],ax
                pop ax
                div cl
                add [si+err_noram.size-err_noram+2],ah
                cbw
                div cl
                add [si+err_noram.size-err_noram],ax
                call writestr_early
                jmp kaboom
enough_ram:
skip_checks:

                section .data16
err_noram       db 'It appears your computer has only '
.size           db '000'
                db 'K of low ("DOS") RAM.', CR, LF
                db 'This version of Syslinux needs '
.need           db '000'
                db 'K to boot.  If you get this', CR, LF
                db 'message in error, hold down the Ctrl key while'
                db 'booting, and I', CR, LF
                db 'will take your word for it.', CR, LF, 0

                section .text16
;
; The code to decompress the PM code and initialize other segments.
;
                extern _lzo1x_decompress_asm_fast

                section .textnr
                bits 32
pm_decompress:
                push 0                          ; Space for decompressed size
                push esp                        ; Pointer to previous word
                push __pm_code_start            ; Target address
                push dword [lzo_data_size]      ; Compressed size
                push dword __pm_code_lma
                call _lzo1x_decompress_asm_fast
                add esp,16
                pop RM_EAX                      ; Decompressed size

                ; Zero bss sections (but not .earlybss, since it may
                ; contain already-live data.)
                xor eax,eax
                mov edi,__bss_start
                mov ecx,__bss_dwords
                rep stosd
                mov edi,__bss16_start
                mov ecx,__bss16_dwords
                rep stosd
                mov edi,__high_clear_start      ; .uibss, .auxseg, .lowmem
                mov ecx,__high_clear_dwords
                rep stosd

                ret

                section .data16
lzo_data_size   dd 0                            ; filled in by compressor

                section .text16
                bits 16