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	;; -----------------------------------------------------------------------
2	;;
3	;; Copyright 1994-2008 H. Peter Anvin - All Rights Reserved
4	;; Copyright 2010 Intel Corporation; author: H. Peter Anvin
5	;;
6	;; 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	;;
17	;; 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	call writestr_early
39	jmp kaboom
40	enough_ram:
41	skip_checks:
42
43	;
44	; 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	;
48	; Note: in Syslinux 4, we should probably just execute the HLT in
49	; protected mode instead.
50	;
51	check_xen:
52	pushfd
53	pushfd
54	pop eax
55	mov edx,eax
56	xor eax,(1 << 21) ; ID flag
57	push eax
58	popfd
59	pushfd
60	pop eax
61	popfd
62	xor eax,edx
63	and eax,(1 << 21)
64	jz .not_xen ; No CPUID
65
66	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