mkinitrd-magellan/isolinux/cpuinit.inc

;; -----------------------------------------------------------------------
;;
;;   Copyright 1994-2008 H. Peter Anvin - All Rights Reserved
;;   Copyright 2010 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.
;;
;; -----------------------------------------------------------------------

;;
;; cpuinit.inc
;;
;; 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
;
dosram_k	equ (real_mode_seg+0x1000) >> 6	; Minimum DOS memory (K)
		int 12h
		cmp ax,dosram_k
		jae enough_ram
		mov si,err_noram
		call writestr_early
		jmp kaboom
enough_ram:
skip_checks:

;
; Detect old versions Xen HVM and disable halt
; Xen HVM older than version 3.3 might be using vmxassist, which breaks
; if HLT is executed in real mode.
;
; Note: in Syslinux 4, we should probably just execute the HLT in
; protected mode instead.
;
check_xen:
		pushfd
		pushfd
		pop eax
		mov edx,eax
		xor eax,(1 << 21)		; ID flag
		push eax
		popfd
		pushfd
		pop eax
		popfd
		xor eax,edx
		and eax,(1 << 21)
		jz .not_xen			; No CPUID

		xor ebx,ebx
		xor ecx,ecx
		xor edx,edx
		mov eax,0x40000000
		cpuid
		cmp ebx,"XenV"
		jne .not_xen
		cmp ecx,"MMXe"
		jne .not_xen
		cmp edx,"nVMM"
		jne .not_xen

		; We're on Xen...
		mov eax,0x40000001
		cpuid
		cmp eax,0x00030003
		jae .not_xen			; Xen >= 3.3, not affected

		; We may be using vmxassist, so disable HLT
		mov byte [ForceNoHalt],1

.not_xen:

		section .data
err_noram	db 'It appears your computer has less than '
		asciidec dosram_k
		db 'K of low ("DOS")'
		db CR, LF
		db 'RAM.  Linux needs at least this amount to boot.  If you get'
		db CR, LF
		db 'this message in error, hold down the Ctrl key while'
		db CR, LF
		db 'booting, and I will take your word for it.', CR, LF, 0
		section .text
1	niro	532	;; -----------------------------------------------------------------------
2			;;
3	niro	1133	;; Copyright 1994-2008 H. Peter Anvin - All Rights Reserved
4			;; Copyright 2010 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			;; cpuinit.inc
16	niro	1133	;;
17	niro	532	;; CPU-dependent initialization and related checks.
18			;;
19
20			check_escapes:
21			mov ah,02h ; Check keyboard flags
22			int 16h
23			mov [KbdFlags],al ; Save for boot prompt check
24			test al,04h ; Ctrl->skip 386 check
25			jnz skip_checks
26
27			;
28			; Now check that there is sufficient low (DOS) memory
29			;
30			; NOTE: Linux doesn't use all of real_mode_seg, but we use the same
31			; segment for COMBOOT images, which can use all 64K
32			;
33			dosram_k equ (real_mode_seg+0x1000) >> 6 ; Minimum DOS memory (K)
34			int 12h
35			cmp ax,dosram_k
36			jae enough_ram
37			mov si,err_noram
38	niro	1133	call writestr_early
39	niro	532	jmp kaboom
40			enough_ram:
41			skip_checks:
42
43			;
44	niro	1133	; Detect old versions Xen HVM and disable halt
45			; Xen HVM older than version 3.3 might be using vmxassist, which breaks
46			; if HLT is executed in real mode.
47	niro	532	;
48	niro	1133	; Note: in Syslinux 4, we should probably just execute the HLT in
49			; protected mode instead.
50	niro	532	;
51	niro	1133	check_xen:
52	niro	532	pushfd
53	niro	1133	pushfd
54	niro	532	pop eax
55	niro	1133	mov edx,eax
56			xor eax,(1 << 21) ; ID flag
57	niro	532	push eax
58			popfd
59			pushfd
60			pop eax
61	niro	1133	popfd
62			xor eax,edx
63			and eax,(1 << 21)
64			jz .not_xen ; No CPUID
65	niro	532
66	niro	1133	xor ebx,ebx
67			xor ecx,ecx
68			xor edx,edx
69			mov eax,0x40000000
70			cpuid
71			cmp ebx,"XenV"
72			jne .not_xen
73			cmp ecx,"MMXe"
74			jne .not_xen
75			cmp edx,"nVMM"
76			jne .not_xen
77
78			; We're on Xen...
79			mov eax,0x40000001
80			cpuid
81			cmp eax,0x00030003
82			jae .not_xen ; Xen >= 3.3, not affected
83
84			; We may be using vmxassist, so disable HLT
85			mov byte [ForceNoHalt],1
86
87			.not_xen:
88
89			section .data
90			err_noram db 'It appears your computer has less than '
91			asciidec dosram_k
92			db 'K of low ("DOS")'
93			db CR, LF
94			db 'RAM. Linux needs at least this amount to boot. If you get'
95			db CR, LF
96			db 'this message in error, hold down the Ctrl key while'
97			db CR, LF
98			db 'booting, and I will take your word for it.', CR, LF, 0
99			section .text