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Diffstat (limited to 'contrib/syslinux-4.02/core/bootsect.inc')
| -rw-r--r-- | contrib/syslinux-4.02/core/bootsect.inc | 237 |
1 files changed, 237 insertions, 0 deletions
diff --git a/contrib/syslinux-4.02/core/bootsect.inc b/contrib/syslinux-4.02/core/bootsect.inc new file mode 100644 index 0000000..b4402f1 --- /dev/null +++ b/contrib/syslinux-4.02/core/bootsect.inc @@ -0,0 +1,237 @@ +;; ----------------------------------------------------------------------- +;; +;; Copyright 1994-2009 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. +;; +;; ----------------------------------------------------------------------- + +;; +;; bootsect.inc +;; +;; Load a boot sector (or other bootstrap program.) +;; +;; Unlike previous versions of this software, this doesn't require that +;; the length is 512 bytes. This allows PXE bootstraps and WinNT +;; "CD boot sectors" to be invoked. +;; + +; +; Load a boot sector +; +is_bootsector: +%if IS_SYSLINUX + ; Transfer zero bytes + push word 0 + jmp short load_bootsec + +is_bss_sector: + ; Transfer the superblock +SuperSize equ $+1 + push word superblock_len_fat16 +%endif +load_bootsec: + mov edi,free_high_memory + mov [trackbuf+4],edi ; Copy from this address + xor dx,dx ; No padding + mov bx,abort_check ; Don't print dots, but allow abort + call load_high + + sub edi,free_high_memory + mov [trackbuf+8],edi ; Save length + + mov eax,7C00h ; Entry point + mov [trackbuf],eax ; Copy to this address + +%if IS_SYSLINUX + xor ecx,ecx + pop cx + + ; For a BSS boot sector we have to patch. + mov esi,superblock + mov edi,free_high_memory+(superblock-bootsec) + call bcopy +%endif + push eax ; Save entry point + + xor edx,edx + xor esi,esi +%if IS_SYSLINUX || IS_EXTLINUX + ; Restore original FDC table + mov eax,[OrigFDCTabPtr] + mov [fdctab],eax + + mov dl,[DriveNumber] + mov si,PartInfo ; Partition info buffer + mov di,800h-18 ; Put partition info here + push di + mov cx,8 ; 16 bytes + xor ax,ax + rep movsw + pop si ; DS:SI points to partition info + xor bx,bx +%elif IS_ISOLINUX + mov dl,[DriveNumber] + xor bx,bx +%elif IS_PXELINUX + mov byte [KeepPXE],03h ; Chainloading + keep PXE + pm_call reset_pxe + lfs si,[InitStack] + ; Put restore DS, EDX and ESI to the true initial values + mov bx,[fs:si+6] + mov edx,[fs:si+28] + mov esi,[fs:si+12] +%endif + +; +; replace_bootstrap for the special case where we have exactly one +; descriptor, based in low memory. We will generate a second descriptor +; to clear remaining FBM. +; + +replace_bootstrap_one: + mov eax,[trackbuf] ; Base address + add eax,[trackbuf+8] ; Length + movzx ecx,word [BIOS_fbm] + shl ecx,10 ; Free Base Memory + sub ecx,eax + mov [trackbuf+12],eax + or dword [trackbuf+16],-1 ; Zero memory + mov [trackbuf+20],ecx + push word 2 ; Length of descriptor list + ; Fall through + +; +; Entrypoint for "shut down and replace bootstrap" -- also invoked by +; the COMBOOT API. This routine expects the entry point (CS, IP) and the +; count of the descriptor sequence on the stack; the shuffle +; descriptors start at the first byte of the trackbuf. +; +; The registers EDX and ESI are passed on to the called program, +; and BX is passed on as DS. +; +replace_bootstrap: + ; + ; Prepare for shutting down + ; + call vgaclearmode + +; +; We jump here when loading a kernel image, so that we don't reset +; the screen mode in "quiet" mode +; +replace_bootstrap_noclearmode: + call cleanup_hardware + + ; + ; Set up initial stack frame (not used by PXE if keeppxe is + ; set - we use the PXE stack then.) + ; + xor ax,ax + mov ds,ax + mov es,ax + +%if IS_PXELINUX + cmp byte [KeepPXE],0 + je .stdstack + les di,[InitStack] ; Reset stack to PXE original + jmp .stackok +%endif +.stdstack: + ; StackBuf is guaranteed to have 44 bytes free immediately + ; above it, and it will not interfere with our existing stack. + mov di,StackBuf + push di + mov cx,22 ; 44 bytes + rep stosw + pop di +.stackok: + + mov [es:di+28],edx ; New EDX + mov [es:di+12],esi ; New ESI + mov [es:di+6],bx ; New DS + +%if IS_PXELINUX == 0 + ; DON'T DO THIS FOR PXELINUX... + ; For PXE, ES:BX -> PXENV+, and this would corrupt + ; that use. + + ; Restore ES:DI -> $PnP (if we were ourselves called + ; that way...) + mov ax,[OrigESDI] + mov bx,[OrigESDI+2] + + mov [es:di+8],ax ; New DI + mov [es:di+4],bx ; New ES +%endif + pop ax ; List length + + push di + push es + + push ds + pop es + + mov ebx,trackbuf + imul di,ax,12 + add di,bx ; DI <- end of list + push di + + ; Terminating entry... + lea eax,[replace_stub] ; Entrypoint + push ax + stosd + xor ax,ax ; EAX[31:16] == 0 already + stosd ; 16-bit mode + stosd ; End of list + + ; Copy the stub + pop di + mov si,__replacestub_lma + mov cx,__replacestub_dwords + rep movsd + + xor ecx,ecx + pop cx ; ECX <- length of list + + pop word [replace_stub.ss] + pop word [replace_stub.esp] + pop dword [replace_stub.csip] + + cli + mov ss,[replace_stub.ss] + mov esp,[replace_stub.esp] + + mov edi,trackbuf + mov esi,edi + + jmp shuffle_and_boot_raw + + ; This stub gets run after the shuffle. It is copied + ; below 0x7c00 in order to properly handle the case + ; of bootstrap replacement. + section .replacestub +replace_stub: + mov cr0,eax + jmp 0:.next +.next: + mov ax,strict word 0 +.ss equ $-2 + mov ss,ax + mov esp,strict dword 0 +.esp equ $-4 + pop gs + pop fs + pop es + pop ds + popad + popfd + jmp 0:0 +.csip equ $-4 + + section .text16 |