Diff of /trunk/mkinitrd-magellan/isolinux/highmem.inc

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	revision 1132 by niro, Sat Sep 1 22:45:15 2007 UTC	revision 1133 by niro, Thu Aug 19 09:50:43 2010 UTC
#	Line 1	Line 1
	;; $Id: highmem.inc,v 1.1 2007-09-01 22:44:04 niro Exp $
1	;; -----------------------------------------------------------------------	;; -----------------------------------------------------------------------
2	;;	;;
3	;;   Copyright 1994-2004 H. Peter Anvin - All Rights Reserved	;;   Copyright 1994-2008 H. Peter Anvin - All Rights Reserved
4	;;	;;
5	;;   This program is free software; you can redistribute it and/or modify	;;   This program is free software; you can redistribute it and/or modify
6	;;   it under the terms of the GNU General Public License as published by	;;   it under the terms of the GNU General Public License as published by
#	Line 13	Line 12
12
13	;;	;;
14	;; highmem.inc	;; highmem.inc
15	;;	;;
16	;; Probe for the size of high memory.  This can be overridden by a	;; Probe for the size of high memory.  This can be overridden by a
17	;; mem= command on the command line while booting a new kernel.	;; mem= command on the command line while booting a new kernel.
18	;;	;;
#	Line 22	Line 21
21
22	;	;
23	; This is set up as a subroutine; it will set up the global variable	; This is set up as a subroutine; it will set up the global variable
24	; HighMemSize.  All registers are preserved.  Assumes DS == CS.	; HighMemSize.  All registers are preserved.
25	;	;
26	highmemsize:	highmemsize:
27	push es	push es
28		pushfd
29	pushad	pushad
30
31		push cs
32		pop es
33
34	;	;
35	; First, try INT 15:E820 (get BIOS memory map)	; First, try INT 15:E820 (get BIOS memory map)
36	;	;
37		; Note: we may have to scan this multiple times, because some (daft) BIOSes
38		; report main memory as multiple contiguous ranges...
39		;
40	get_e820:	get_e820:
	xor ebx,ebx ; Start with first record
41	mov dword [E820Max],-(1 << 20) ; Max amount of high memory	mov dword [E820Max],-(1 << 20) ; Max amount of high memory
42	mov dword [E820Mem],ebx ; Detected amount of high memory	mov dword [E820Mem],(1 << 20) ; End of detected high memory
43	mov es,bx ; Need ES = DS = 0 for now	.start_over:
44		mov di,E820Buf
45		xor ax,ax
46		mov cx,10
47		rep stosw ; Clear buffer
48		xor ebx,ebx ; Start with first record
49	jmp short .do_e820 ; Skip "at end" check first time!	jmp short .do_e820 ; Skip "at end" check first time!
50	.int_loop: and ebx,ebx ; If we're back at beginning...	.int_loop: and ebx,ebx ; If we're back at beginning...
51	jz .e820_done ; ... we're done	jz .e820_done ; ... we're done
52	.do_e820: mov eax,0000E820h	.do_e820: mov eax,0000E820h
53	mov edx,534D4150h ; "SMAP" backwards	mov edx,534D4150h ; "SMAP" backwards
54	xor ecx,ecx	xor ecx,ecx
55	mov cl,20 ; ECX <- 20	mov cl,20 ; ECX <- 20 (size of buffer)
56	mov di,E820Buf	mov di,E820Buf
57	int 15h	int 15h
58	jnc .no_carry	jnc .no_carry
#	Line 53  get_e820:	Line 63  get_e820:
63	.no_carry:	.no_carry:
64	cmp eax,534D4150h	cmp eax,534D4150h
65	jne no_e820	jne no_e820
66		cmp cx,20
67		jb no_e820
68
69	;	;
70	; Look for a memory block starting at <= 1 MB and continuing upward	; Look for a memory block starting at <= 1 MB and continuing upward
71	;	;
72	cmp dword [E820Buf+4], byte 0	cmp dword [E820Buf+4], byte 0
73	ja .int_loop ; Start >= 4 GB?	ja .int_loop ; Start >= 4 GB?
74	mov edx, (1 << 20)	mov eax, [E820Buf]
75	sub edx, [E820Buf]	cmp dword [E820Buf+16],1
76	jnb .ram_range ; Start >= 1 MB?	je .is_ram ; Is it memory?
77	; If we get here, it starts > 1 MB but < 4 GB; if this is a	;
78	; *non*-memory range, remember this as unusable; some BIOSes	; Non-memory range.  Remember this as a limit; some BIOSes get the length
79	; get the length of primary RAM wrong!	; of primary RAM incorrect!
80	cmp dword [E820Buf+16], byte 1	;
81	je .int_loop ; If it's memory, don't worry about it	.not_ram:
82	neg edx ; This means what for memory limit?	cmp eax, (1 << 20)
83	cmp edx,[E820Max] ; Better or worse	jb .int_loop ; Starts in lowmem region
84	jnb .int_loop	cmp eax,[E820Max]
85	mov [E820Max],edx	jae .int_loop ; Already above limit
86		mov [E820Max],eax ; Set limit
87	jmp .int_loop	jmp .int_loop
	.ram_range:
	stc
	sbb eax,eax ; eax <- 0xFFFFFFFF
	cmp dword [E820Buf+12], byte 0
	ja .huge ; Size >= 4 GB
	mov eax, [E820Buf+8]
	.huge: sub eax, edx ; Adjust size to start at 1 MB
	jbe .int_loop ; Completely below 1 MB?
	; Now EAX contains the size of memory 1 MB...up
	cmp dword [E820Buf+16], byte 1
	jne .int_loop ; High memory isn't usable memory!!!!
88
89	; We're good!	.is_ram:
90		cmp eax,[E820Mem]
91		ja .int_loop ; Not contiguous with our starting point
92		add eax,[E820Buf+8]
93		jc .overflow
94		cmp dword [E820Buf+12],0
95		je .nooverflow
96		.overflow:
97		or eax,-1
98		.nooverflow:
99		cmp eax,[E820Mem]
100		jbe .int_loop ; All is below our baseline
101	mov [E820Mem],eax	mov [E820Mem],eax
102	jmp .int_loop ; Still need to add low 1 MB	jmp .start_over ; Start over in case we find an adjacent range
103
104	.e820_done:	.e820_done:
105	mov eax,[E820Mem]	mov eax,[E820Mem]
106	and eax,eax	cmp eax,[E820Max]
107	jz no_e820 ; Nothing found by E820?	jna .not_limited
	cmp eax,[E820Max] ; Make sure we're not limited
	jna got_highmem_add1mb
108	mov eax,[E820Max]	mov eax,[E820Max]
109	jmp got_highmem_add1mb	.not_limited:
110		cmp eax,(1 << 20)
111		ja got_highmem ; Did we actually find memory?
112		; otherwise fall through
113
114	;	;
115	; INT 15:E820 failed.  Try INT 15:E801.	; INT 15:E820 failed.  Try INT 15:E801.
#	Line 112  no_e820:	Line 125  no_e820:
125	mov ax,bx	mov ax,bx
126	shl eax,16 ; 64K chunks	shl eax,16 ; 64K chunks
127	add eax,(16 << 20) ; Add first 16M	add eax,(16 << 20) ; Add first 16M
128	jmp short got_highmem	jmp short got_highmem
129
130	;	;
131	; INT 15:E801 failed.  Try INT 15:88.	; INT 15:E801 failed.  Try INT 15:88.
#	Line 126  no_e801:	Line 139  no_e801:
139	e801_hole:	e801_hole:
140	and eax,0ffffh	and eax,0ffffh
141	shl eax,10 ; Convert from kilobytes	shl eax,10 ; Convert from kilobytes
	got_highmem_add1mb:
142	add eax,(1 << 20) ; First megabyte	add eax,(1 << 20) ; First megabyte
143	got_highmem:	got_highmem:
144	%if HIGHMEM_SLOP != 0	%if HIGHMEM_SLOP != 0
#	Line 134  got_highmem:	Line 146  got_highmem:
146	%endif	%endif
147	mov [HighMemSize],eax	mov [HighMemSize],eax
148	popad	popad
149		popfd
150	pop es	pop es
151	ret ; Done!	ret ; Done!
152

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