mkinitrd-magellan/isolinux/bootsect.inc

;; -----------------------------------------------------------------------
;;
;;   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,100000h
		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,100000h
		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,100000h+(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
		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:
		mov di,7C00h-44
		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 .text
1	niro	532	;; -----------------------------------------------------------------------
2			;;
3	niro	1133	;; Copyright 1994-2009 H. Peter Anvin - All Rights Reserved
4			;; Copyright 2009 Intel Corporation; author: H. Peter Anvin
5			;;
6	niro	532	;; This program is free software; you can redistribute it and/or modify
7			;; it under the terms of the GNU General Public License as published by
8			;; the Free Software Foundation, Inc., 53 Temple Place Ste 330,
9			;; Boston MA 02111-1307, USA; either version 2 of the License, or
10			;; (at your option) any later version; incorporated herein by reference.
11			;;
12			;; -----------------------------------------------------------------------
13
14			;;
15			;; bootsect.inc
16	niro	1133	;;
17	niro	532	;; Load a boot sector (or other bootstrap program.)
18			;;
19			;; Unlike previous versions of this software, this doesn't require that
20			;; the length is 512 bytes. This allows PXE bootstraps and WinNT
21			;; "CD boot sectors" to be invoked.
22			;;
23
24			;
25			; Load a boot sector
26			;
27			is_bootsector:
28	niro	1133	%if IS_SYSLINUX
29	niro	532	; Transfer zero bytes
30	niro	1133	push word 0
31	niro	532	jmp short load_bootsec
32
33			is_bss_sector:
34			; Transfer the superblock
35	niro	1133	SuperSize equ $+1
36			push word superblock_len_fat16
37	niro	532	%endif
38			load_bootsec:
39	niro	1133	mov edi,100000h
40	niro	532	mov [trackbuf+4],edi ; Copy from this address
41			xor dx,dx ; No padding
42	niro	1133	mov bx,abort_check ; Don't print dots, but allow abort
43	niro	532	call load_high
44
45			sub edi,100000h
46			mov [trackbuf+8],edi ; Save length
47
48			mov eax,7C00h ; Entry point
49			mov [trackbuf],eax ; Copy to this address
50
51	niro	1133	%if IS_SYSLINUX
52			xor ecx,ecx
53			pop cx
54	niro	532
55			; For a BSS boot sector we have to patch.
56			mov esi,superblock
57			mov edi,100000h+(superblock-bootsec)
58			call bcopy
59			%endif
60	niro	1133	push eax ; Save entry point
61	niro	532
62			xor edx,edx
63			xor esi,esi
64	niro	1133	%if IS_SYSLINUX \|\| IS_EXTLINUX
65	niro	532	; Restore original FDC table
66			mov eax,[OrigFDCTabPtr]
67			mov [fdctab],eax
68
69			mov dl,[DriveNumber]
70			mov si,PartInfo ; Partition info buffer
71			mov di,800h-18 ; Put partition info here
72			push di
73			mov cx,8 ; 16 bytes
74			xor ax,ax
75			rep movsw
76			pop si ; DS:SI points to partition info
77	niro	1133	xor bx,bx
78	niro	532	%elif IS_ISOLINUX
79	niro	1133	mov dl,[DriveNumber]
80			xor bx,bx
81	niro	532	%elif IS_PXELINUX
82	niro	1133	mov byte [KeepPXE],03h ; Chainloading + keep PXE
83	niro	532	call reset_pxe
84	niro	1133	lfs si,[InitStack]
85			; Put restore DS, EDX and ESI to the true initial values
86			mov bx,[fs:si+6]
87			mov edx,[fs:si+28]
88			mov esi,[fs:si+12]
89	niro	532	%endif
90
91			;
92			; replace_bootstrap for the special case where we have exactly one
93	niro	1133	; descriptor, based in low memory. We will generate a second descriptor
94			; to clear remaining FBM.
95	niro	532	;
96
97			replace_bootstrap_one:
98	niro	1133	mov eax,[trackbuf] ; Base address
99			add eax,[trackbuf+8] ; Length
100			movzx ecx,word [BIOS_fbm]
101			shl ecx,10 ; Free Base Memory
102			sub ecx,eax
103			mov [trackbuf+12],eax
104			or dword [trackbuf+16],-1 ; Zero memory
105			mov [trackbuf+20],ecx
106			push word 2 ; Length of descriptor list
107	niro	532	; Fall through
108
109	niro	1133	;
110	niro	532	; Entrypoint for "shut down and replace bootstrap" -- also invoked by
111	niro	1133	; the COMBOOT API. This routine expects the entry point (CS, IP) and the
112			; count of the descriptor sequence on the stack; the shuffle
113			; descriptors start at the first byte of the trackbuf.
114			;
115			; The registers EDX and ESI are passed on to the called program,
116			; and BX is passed on as DS.
117			;
118	niro	532	replace_bootstrap:
119			;
120			; Prepare for shutting down
121			;
122			call vgaclearmode
123
124	niro	1133	;
125			; We jump here when loading a kernel image, so that we don't reset
126			; the screen mode in "quiet" mode
127			;
128			replace_bootstrap_noclearmode:
129			call cleanup_hardware
130
131	niro	532	;
132			; Set up initial stack frame (not used by PXE if keeppxe is
133			; set - we use the PXE stack then.)
134			;
135			xor ax,ax
136			mov ds,ax
137	niro	1133	mov es,ax
138	niro	532
139			%if IS_PXELINUX
140	niro	1133	cmp byte [KeepPXE],0
141			je .stdstack
142	niro	532	les di,[InitStack] ; Reset stack to PXE original
143			jmp .stackok
144			%endif
145			.stdstack:
146			mov di,7C00h-44
147			push di
148			mov cx,22 ; 44 bytes
149			rep stosw
150			pop di
151			.stackok:
152
153	niro	1133	mov [es:di+28],edx ; New EDX
154			mov [es:di+12],esi ; New ESI
155			mov [es:di+6],bx ; New DS
156	niro	532
157	niro	1133	%if IS_PXELINUX == 0
158			; DON'T DO THIS FOR PXELINUX...
159			; For PXE, ES:BX -> PXENV+, and this would corrupt
160			; that use.
161	niro	532
162	niro	1133	; Restore ES:DI -> $PnP (if we were ourselves called
163			; that way...)
164			mov ax,[OrigESDI]
165			mov bx,[OrigESDI+2]
166
167			mov [es:di+8],ax ; New DI
168			mov [es:di+4],bx ; New ES
169			%endif
170			pop ax ; List length
171
172			push di
173			push es
174
175			push ds
176			pop es
177
178			mov ebx,trackbuf
179			imul di,ax,12
180			add di,bx ; DI <- end of list
181			push di
182
183			; Terminating entry...
184			lea eax,[replace_stub] ; Entrypoint
185			push ax
186			stosd
187			xor ax,ax ; EAX[31:16] == 0 already
188			stosd ; 16-bit mode
189			stosd ; End of list
190
191			; Copy the stub
192			pop di
193			mov si,__replacestub_lma
194			mov cx,__replacestub_dwords
195			rep movsd
196
197			xor ecx,ecx
198			pop cx ; ECX <- length of list
199
200			pop word [replace_stub.ss]
201			pop word [replace_stub.esp]
202			pop dword [replace_stub.csip]
203
204	niro	532	cli
205	niro	1133	mov ss,[replace_stub.ss]
206			mov esp,[replace_stub.esp]
207	niro	532
208	niro	1133	mov edi,trackbuf
209			mov esi,edi
210	niro	532
211	niro	1133	jmp shuffle_and_boot_raw
212
213			; This stub gets run after the shuffle. It is copied
214			; below 0x7c00 in order to properly handle the case
215			; of bootstrap replacement.
216			section .replacestub
217			replace_stub:
218			mov cr0,eax
219			jmp 0:.next
220			.next:
221			mov ax,strict word 0
222			.ss equ $-2
223			mov ss,ax
224			mov esp,strict dword 0
225			.esp equ $-4
226			pop gs
227			pop fs
228			pop es
229			pop ds
230			popad
231			popfd
232			jmp 0:0
233			.csip equ $-4
234
235			section .text