fw_builder/make-nk/boot.S

!   Linux kernel setup for WYSE Winterm devices (at least WT3320SE)
!   Based on setup code for AMD Élan devices by Anders Larsen
!
!   Winterm version Copyright (C) 2005 by Wilmer van der Gaast
!
!   Portions are Copyright (C) 2000 by Denis Hatebur and TueViT Essen
!   Portions are Copyright (C) 2000 by Anders Larsen and Baumer Ident GmbH
!
!   Derived from setup.S   Copyright (C) 1991-1997 Linus Torvalds et al.
!
!   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; either version 2 of the License, or
!   (at your option) any later version.
!
!   This program is distributed in the hope that it will be useful,
!   but WITHOUT ANY WARRANTY; without even the implied warranty of
!   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
!   GNU General Public License for more details.
!
!   You should have received a copy of the GNU General Public License
!   along with this program. If not, write to the Free Software
!   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

#include <asm/segment.h>

	.org 0x0
	.text

USE32
entry CODE1
	
	.org	0x1e0
	
		; Note: This is the size of *extended* memory, i.e. the memory above
		; the 1M mark!
mem_size:	.long	0
	
	.org	0x1f1
	
		.byte	0		; setup_sects
		.word	0		; read-only rootfs?
		.long	0		; syssize (not necessary in protocol 2.02)
		.word	0		; ram_size (don't use!)
		.word	0xffff		; vid_mode
		.word	0x0100		; root_dev
		.word	0xaa55		; magic!
	
start:
		.word	0
! ------------------------ start of header --------------------------------
!
! SETUP-header, must start at CS:2 (old 0x9020:2)
!
		.ascii	"HdrS"		! Signature for SETUP-header
		.word	0x0202		! Version number of header format
					! (must be >= 0x0105
					! else old loadlin-1.5 will fail)
realmode_swtch:	.word	0,0		! default_switch,SETUPSEG
start_sys_seg:	.word	0x1000
		.word	kernel_version	!pointing to kernel version string
  ! note: above part of header is compatible with loadlin-1.5 (header v1.5),
  !        must not change it

type_of_loader:	.byte	0xff		! = 0, old one (LILO, Loadlin,
					!      Bootlin, SYSLX, bootsect...)
					! else it is set by the loader:
					! 0xTV: T=0 for LILO
					!	T=1 for Loadlin
					!	T=2 for bootsect-loader
					!	T=3 for SYSLX
					!	T=4 for ETHERBOOT
					!       V = version
wloadflags:				! flags, unused bits must be zero (RFU)
		.byte	0x01


setup_move_size: .word  0x8000		! size to move, when we (setup) are not
					! loaded at 0x90000. We will move ourselves
					! to 0x90000 then just before jumping into
					! the kernel. However, only the loader
					! know how much of data behind us also needs
					! to be loaded.
code32_start:				! here loaders can put a different
		.long	0x100000	! 0x100000 = default for big kernel


ramdisk_image:	.long	0		! address of loaded ramdisk image
					! Here the loader (or kernel generator) puts
					! the 32-bit address were it loaded the image.
					! This only will be interpreted by the kernel.
ramdisk_size:	.long	0		! its size in bytes
bootsect_kludge:
		.word   0,0
heap_end_ptr:	.word	0x9010+eof/16	! space from here (exclusive) down to
					! end of setup code can be used by setup
					! for local heap purposes.

! ------------------------ end of header ----------------------------------


.org 0x1000

start_of_setup:

CODE1:
	cli			! Disable Interrupts
	
	call nl_out
	
	mov al, #'W
	call ch_out
	mov al, #'I
	call ch_out

	mov al, #0x80
	out #0x70, al		! Disable NMIs

	mov al, #'L
	call ch_out
	call ch_out
	mov al, #'O
	call ch_out

	call nl_out
	
	mov esi, kernel_version+0x90000
	call str_out
	call nl_out
	
	mov esi, params_head+0x90000
	call str_out
	mov esi, kernelparam+0x90000
	call str_out
	call nl_out
	
	mov eax, kernelparam+0x90000
	mov [0x90228], eax
	
	; Only do memory detection (and initrd move) if it's not specified yet
	mov eax, [mem_size+0x90000]
	or eax, eax
	jz do_mem_detect
	
	; Hurray for indirect jumps...
	mov ecx, skip_mem_detect+0x90000
	jmp ecx
	
do_mem_detect:	
	mov esi, memcount_msg+0x90000
	call str_out
	
	; Disable memory caching for the memory test, it might spoil the
	; results
	mov eax, cr0
	or eax, 0x40000000
	mov cr0, eax
	wbinvd
	
	; Start testing memory at the 8MB mark, so we assume there is at
	; least that much (most Winterms have at least 32MB anyway)
	mov edi, 8*1048576-4
memsize_loop:
	mov eax, [edi]
	xor eax, 0x55555555	; This part is kind of fragile, mov [edi], eax &&
	xor [edi], 0x55555555	; cmp [edi], eax always returns ZF, even if [edi]
	cmp eax, [edi]		; is not memory, for example. This works though.
	jne memsize_found
	xor [edi], 0x55555555	; Restore memory, there might be an initrd here.
	add edi, 65536
	jmp memsize_loop
memsize_found:
	sub edi, 65532
	mov eax, edi
	call hex_out
	
	; Kernel wants this value in 1K blocks, and not counting "conventional"
	; memory.
	shr eax, 10
	sub eax, 1024
	mov [mem_size+0x90000], eax
	
	; nl_out touches al, so don't do this earlier
	call nl_out
	
	; Turn memory cache back on, or the rest will be sloooooow :-)
	mov eax, cr0
	and eax, 0x9fffffff
	mov cr0, eax
	
	; Now let's see, do we have a RAM-disk? If so, we should try to keep
	; it as high in memory as possible. Don't start at the first byte with
	; moving, this would make a mess if there's an overlap.
	; We'll go backwards.
	cmp dword [ramdisk_image+0x90000], 0
	jz skip_mem_detect
	
	mov esi, rdmove_msg+0x90000
	call str_out
	
	mov esi, [ramdisk_image+0x90000]
	add esi, [ramdisk_size+0x90000]
	sub esi, 4
	
	; edi still contains the memory size in bytes!
	sub edi, [ramdisk_size+0x90000]
	and edi, 0xfffe0000
	mov [ramdisk_image+0x90000], edi	; Save the position now already
	add edi, [ramdisk_size+0x90000]
	sub edi, 4
	
	; Count the number of DWORDS we have to move
	mov ecx, [ramdisk_size+0x90000]
	add ecx, 3
	shr ecx, 2
	
	std
	rep
	movsd
	cld
	
	; Dump the new position. Not too useful, but nice for debugging.
	mov eax, [ramdisk_image+0x90000]
	call hex_out
	call nl_out
	
skip_mem_detect:
	; Old place for memory size, don't know if any recent kernel really
	; cares, but just to be sure..
	mov eax, [mem_size+0x90000]
	mov [0x90002], ax
	
	; Set up IDT/GDTs that are useful for the kernel
	seg ds
	lidt	[idt_48+0x90000]	! load idt with 0,0
	seg ds
	lgdt	[gdt_48+0x90000]	! load gdt with whatever appropriate
	
! make sure any possible coprocessor is properly reset..

	xor	ax,ax
	out	#0xf0,al
	call	delay
	out	#0xf1,al
	call	delay

! well, that went ok, I hope. Now we have to reprogram the interrupts :-(
! we put them right after the intel-reserved hardware interrupts, at
! int 0x20-0x2F. There they won't mess up anything. Sadly IBM really
! messed this up with the original PC, and they haven't been able to
! rectify it afterwards. Thus the bios puts interrupts at 0x08-0x0f,
! which is used for the internal hardware interrupts as well. We just
! have to reprogram the 8259's, and it isn't fun.

	mov	al,#0x11		! initialization sequence
	out	#0x20,al		! send it to 8259A-1
	call	delay
	out	#0xA0,al		! and to 8259A-2
	call	delay
	mov	al,#0x20		! start of hardware int's (0x20)
	out	#0x21,al
	call	delay
	mov	al,#0x28		! start of hardware int's 2 (0x28)
	out	#0xA1,al
	call	delay
	mov	al,#0x04		! 8259-1 is master
	out	#0x21,al
	call	delay
	mov	al,#0x02		! 8259-2 is slave
	out	#0xA1,al
	call	delay
	mov	al,#0x01		! 8086 mode for both
	out	#0x21,al
	call	delay
	out	#0xA1,al
	call	delay
	mov	al,#0xFF		! mask off all interrupts for now
	out	#0xA1,al
	call	delay
	mov	al,#0xFB		! mask all irq's but irq2 which
	out	#0x21,al		! is cascaded
	
	mov	esi, start_linux+0x90000
	call	str_out
	
	mov	bx, #0
	mov	esi, #0x90000
	
; JMP NEW_CS:00100000
	db	0xea
	dd	0x100000
	dw	0x10

!
! Delay is needed after doing I/O
!
delay:
	.word	0x00eb			! jmp $+2
	ret

!******************************************************
! Outputs Character: AL -> COM1
!******************************************************
ch_out:	
!	ret
        push eax

	mov eax, #0x00008000
loop3:	sub eax, #0x1
	jnz loop3
	
	mov dx, #0x3f8+0x5
ch_w:	in al, dx
	and al, #0x40
	jz ch_w

	pop eax
	
ch_outw:	
	mov dx, #0x3f8
	out dx, al			! serial out .... only try
	ret

!******************************************************
! Outputs a \r\n
!******************************************************
nl_out:
	mov	al, 0x0d
	call	ch_out
	mov	al, 0x0a
	call	ch_out
	ret

!******************************************************
! Outputs a String: [ESI] -> COM1
!******************************************************
str_out:
	lodsb
	or	al, al
	jz	str_out_end
	call	ch_out
	jmp	str_out
str_out_end:
	ret

!******************************************************
! Outputs a Hex number: EAX -> COM
!******************************************************
hex_out:
	mov	ecx, 8

ho_loop:
	rol	eax, #4
	push	ax
	and	al, #0x0f
	add	al, #'0
	cmp	al, #'9
	jbe	ho_1
	add	al, #7
ho_1:	call	ch_out
	pop	ax
	loop	ho_loop
	
	push	ax
	mov	al, #0x20
	call	ch_out
	pop	ax
	
	ret

!******************************************************
!**** D A T A *****************************************
!******************************************************

gdt_len:	dw 0
gdt_base:	dd 0

kernel_version:	.ascii "Linux "
		.ascii "                              " ; version goes here
		.byte	0x0

start_linux:	.word	0x0a0d
		.ascii "Starting Linux..."
		.word	0x0a0d
		.byte	0x0

params_head:	.ascii "Kernel parameters: "
		.byte	0x0

memcount_msg:	.ascii "Counting memory... "
		.byte	0x0

rdmove_msg:	.ascii "Moving initrd... "
		.byte	0x0

	.align 16
	
gdt:		.word	0,0,0,0
		.word	0,0,0,0
	
		.word	0xFFFF		! 4Gb - (0x100000*0x1000 = 4Gb)
		.word	0x0000		! base address=0
		.word	0x9A00		! code read/exec
		.word	0x00CF		! granularity=4096, 386 (+5th nibble of limit)
	
		.word	0xFFFF		! 4Gb - (0x100000*0x1000 = 4Gb)
		.word	0x0000		! base address=0
		.word	0x9200		! data read/write
		.word	0x00CF		! granularity=4096, 386 (+5th nibble of limit)
gdt_end:	.word	0

idt_48:		.word	0		! idt limit=0
		.long	0		! idt base=0L

gdt_48:		.word	gdt_end-gdt	! 
		.long	0x90000+gdt	! gdt base = 0X9xxxx


		.byte	0x0
kernelparam:	;.ascii	"console=ttyS0,38400N8"
;		.ascii	" root=/dev/ram0 rw "
		.ascii  " root=/dev/sda1 lang=us quiet tz=Europe/Amsterdam"
		.ascii  " video=nscfb:vmode:1024x768-16,vfreq:75 splash=silent"
		.ascii	" reboot=bios"
		.byte	0x0


!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

setup_sig1:	.word	0xAA55
setup_sig2:	.word	0x5A5A

eof:
1	niro	658	! Linux kernel setup for WYSE Winterm devices (at least WT3320SE)
2			! Based on setup code for AMD Élan devices by Anders Larsen
3			!
4			! Winterm version Copyright (C) 2005 by Wilmer van der Gaast
5			!
6			! Portions are Copyright (C) 2000 by Denis Hatebur and TueViT Essen
7			! Portions are Copyright (C) 2000 by Anders Larsen and Baumer Ident GmbH
8			!
9			! Derived from setup.S Copyright (C) 1991-1997 Linus Torvalds et al.
10			!
11			! This program is free software; you can redistribute it and/or modify
12			! it under the terms of the GNU General Public License as published by
13			! the Free Software Foundation; either version 2 of the License, or
14			! (at your option) any later version.
15			!
16			! This program is distributed in the hope that it will be useful,
17			! but WITHOUT ANY WARRANTY; without even the implied warranty of
18			! MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19			! GNU General Public License for more details.
20			!
21			! You should have received a copy of the GNU General Public License
22			! along with this program. If not, write to the Free Software
23			! Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24
25			#include <asm/segment.h>
26
27			.org 0x0
28			.text
29
30			USE32
31			entry CODE1
32
33			.org 0x1e0
34
35			; Note: This is the size of extended memory, i.e. the memory above
36			; the 1M mark!
37			mem_size: .long 0
38
39			.org 0x1f1
40
41			.byte 0 ; setup_sects
42			.word 0 ; read-only rootfs?
43			.long 0 ; syssize (not necessary in protocol 2.02)
44			.word 0 ; ram_size (don't use!)
45			.word 0xffff ; vid_mode
46			.word 0x0100 ; root_dev
47			.word 0xaa55 ; magic!
48
49			start:
50			.word 0
51			! ------------------------ start of header --------------------------------
52			!
53			! SETUP-header, must start at CS:2 (old 0x9020:2)
54			!
55			.ascii "HdrS" ! Signature for SETUP-header
56			.word 0x0202 ! Version number of header format
57			! (must be >= 0x0105
58			! else old loadlin-1.5 will fail)
59			realmode_swtch: .word 0,0 ! default_switch,SETUPSEG
60			start_sys_seg: .word 0x1000
61			.word kernel_version !pointing to kernel version string
62			! note: above part of header is compatible with loadlin-1.5 (header v1.5),
63			! must not change it
64
65			type_of_loader: .byte 0xff ! = 0, old one (LILO, Loadlin,
66			! Bootlin, SYSLX, bootsect...)
67			! else it is set by the loader:
68			! 0xTV: T=0 for LILO
69			! T=1 for Loadlin
70			! T=2 for bootsect-loader
71			! T=3 for SYSLX
72			! T=4 for ETHERBOOT
73			! V = version
74			wloadflags: ! flags, unused bits must be zero (RFU)
75			.byte 0x01
76
77
78			setup_move_size: .word 0x8000 ! size to move, when we (setup) are not
79			! loaded at 0x90000. We will move ourselves
80			! to 0x90000 then just before jumping into
81			! the kernel. However, only the loader
82			! know how much of data behind us also needs
83			! to be loaded.
84			code32_start: ! here loaders can put a different
85			.long 0x100000 ! 0x100000 = default for big kernel
86
87
88			ramdisk_image: .long 0 ! address of loaded ramdisk image
89			! Here the loader (or kernel generator) puts
90			! the 32-bit address were it loaded the image.
91			! This only will be interpreted by the kernel.
92			ramdisk_size: .long 0 ! its size in bytes
93			bootsect_kludge:
94			.word 0,0
95			heap_end_ptr: .word 0x9010+eof/16 ! space from here (exclusive) down to
96			! end of setup code can be used by setup
97			! for local heap purposes.
98
99			! ------------------------ end of header ----------------------------------
100
101
102
103
104			.org 0x1000
105
106			start_of_setup:
107
108			CODE1:
109			cli ! Disable Interrupts
110
111			call nl_out
112
113			mov al, #'W
114			call ch_out
115			mov al, #'I
116			call ch_out
117
118			mov al, #0x80
119			out #0x70, al ! Disable NMIs
120
121			mov al, #'L
122			call ch_out
123			call ch_out
124			mov al, #'O
125			call ch_out
126
127			call nl_out
128
129			mov esi, kernel_version+0x90000
130			call str_out
131			call nl_out
132
133			mov esi, params_head+0x90000
134			call str_out
135			mov esi, kernelparam+0x90000
136			call str_out
137			call nl_out
138
139			mov eax, kernelparam+0x90000
140			mov [0x90228], eax
141
142			; Only do memory detection (and initrd move) if it's not specified yet
143			mov eax, [mem_size+0x90000]
144			or eax, eax
145			jz do_mem_detect
146
147			; Hurray for indirect jumps...
148			mov ecx, skip_mem_detect+0x90000
149			jmp ecx
150
151			do_mem_detect:
152			mov esi, memcount_msg+0x90000
153			call str_out
154
155			; Disable memory caching for the memory test, it might spoil the
156			; results
157			mov eax, cr0
158			or eax, 0x40000000
159			mov cr0, eax
160			wbinvd
161
162			; Start testing memory at the 8MB mark, so we assume there is at
163			; least that much (most Winterms have at least 32MB anyway)
164			mov edi, 8*1048576-4
165			memsize_loop:
166			mov eax, [edi]
167			xor eax, 0x55555555 ; This part is kind of fragile, mov [edi], eax &&
168			xor [edi], 0x55555555 ; cmp [edi], eax always returns ZF, even if [edi]
169			cmp eax, [edi] ; is not memory, for example. This works though.
170			jne memsize_found
171			xor [edi], 0x55555555 ; Restore memory, there might be an initrd here.
172			add edi, 65536
173			jmp memsize_loop
174			memsize_found:
175			sub edi, 65532
176			mov eax, edi
177			call hex_out
178
179			; Kernel wants this value in 1K blocks, and not counting "conventional"
180			; memory.
181			shr eax, 10
182			sub eax, 1024
183			mov [mem_size+0x90000], eax
184
185			; nl_out touches al, so don't do this earlier
186			call nl_out
187
188			; Turn memory cache back on, or the rest will be sloooooow :-)
189			mov eax, cr0
190			and eax, 0x9fffffff
191			mov cr0, eax
192
193			; Now let's see, do we have a RAM-disk? If so, we should try to keep
194			; it as high in memory as possible. Don't start at the first byte with
195			; moving, this would make a mess if there's an overlap.
196			; We'll go backwards.
197			cmp dword [ramdisk_image+0x90000], 0
198			jz skip_mem_detect
199
200			mov esi, rdmove_msg+0x90000
201			call str_out
202
203			mov esi, [ramdisk_image+0x90000]
204			add esi, [ramdisk_size+0x90000]
205			sub esi, 4
206
207			; edi still contains the memory size in bytes!
208			sub edi, [ramdisk_size+0x90000]
209			and edi, 0xfffe0000
210			mov [ramdisk_image+0x90000], edi ; Save the position now already
211			add edi, [ramdisk_size+0x90000]
212			sub edi, 4
213
214			; Count the number of DWORDS we have to move
215			mov ecx, [ramdisk_size+0x90000]
216			add ecx, 3
217			shr ecx, 2
218
219			std
220			rep
221			movsd
222			cld
223
224			; Dump the new position. Not too useful, but nice for debugging.
225			mov eax, [ramdisk_image+0x90000]
226			call hex_out
227			call nl_out
228
229			skip_mem_detect:
230			; Old place for memory size, don't know if any recent kernel really
231			; cares, but just to be sure..
232			mov eax, [mem_size+0x90000]
233			mov [0x90002], ax
234
235			; Set up IDT/GDTs that are useful for the kernel
236			seg ds
237			lidt [idt_48+0x90000] ! load idt with 0,0
238			seg ds
239			lgdt [gdt_48+0x90000] ! load gdt with whatever appropriate
240
241			! make sure any possible coprocessor is properly reset..
242
243			xor ax,ax
244			out #0xf0,al
245			call delay
246			out #0xf1,al
247			call delay
248
249			! well, that went ok, I hope. Now we have to reprogram the interrupts :-(
250			! we put them right after the intel-reserved hardware interrupts, at
251			! int 0x20-0x2F. There they won't mess up anything. Sadly IBM really
252			! messed this up with the original PC, and they haven't been able to
253			! rectify it afterwards. Thus the bios puts interrupts at 0x08-0x0f,
254			! which is used for the internal hardware interrupts as well. We just
255			! have to reprogram the 8259's, and it isn't fun.
256
257			mov al,#0x11 ! initialization sequence
258			out #0x20,al ! send it to 8259A-1
259			call delay
260			out #0xA0,al ! and to 8259A-2
261			call delay
262			mov al,#0x20 ! start of hardware int's (0x20)
263			out #0x21,al
264			call delay
265			mov al,#0x28 ! start of hardware int's 2 (0x28)
266			out #0xA1,al
267			call delay
268			mov al,#0x04 ! 8259-1 is master
269			out #0x21,al
270			call delay
271			mov al,#0x02 ! 8259-2 is slave
272			out #0xA1,al
273			call delay
274			mov al,#0x01 ! 8086 mode for both
275			out #0x21,al
276			call delay
277			out #0xA1,al
278			call delay
279			mov al,#0xFF ! mask off all interrupts for now
280			out #0xA1,al
281			call delay
282			mov al,#0xFB ! mask all irq's but irq2 which
283			out #0x21,al ! is cascaded
284
285			mov esi, start_linux+0x90000
286			call str_out
287
288			mov bx, #0
289			mov esi, #0x90000
290
291			; JMP NEW_CS:00100000
292			db 0xea
293			dd 0x100000
294			dw 0x10
295
296			!
297			! Delay is needed after doing I/O
298			!
299			delay:
300			.word 0x00eb ! jmp $+2
301			ret
302
303			!******************************************************
304			! Outputs Character: AL -> COM1
305			!******************************************************
306			ch_out:
307			! ret
308			push eax
309
310			mov eax, #0x00008000
311			loop3: sub eax, #0x1
312			jnz loop3
313
314			mov dx, #0x3f8+0x5
315			ch_w: in al, dx
316			and al, #0x40
317			jz ch_w
318
319			pop eax
320
321			ch_outw:
322			mov dx, #0x3f8
323			out dx, al ! serial out .... only try
324			ret
325
326			!******************************************************
327			! Outputs a \r\n
328			!******************************************************
329			nl_out:
330			mov al, 0x0d
331			call ch_out
332			mov al, 0x0a
333			call ch_out
334			ret
335
336			!******************************************************
337			! Outputs a String: [ESI] -> COM1
338			!******************************************************
339			str_out:
340			lodsb
341			or al, al
342			jz str_out_end
343			call ch_out
344			jmp str_out
345			str_out_end:
346			ret
347
348			!******************************************************
349			! Outputs a Hex number: EAX -> COM
350			!******************************************************
351			hex_out:
352			mov ecx, 8
353
354			ho_loop:
355			rol eax, #4
356			push ax
357			and al, #0x0f
358			add al, #'0
359			cmp al, #'9
360			jbe ho_1
361			add al, #7
362			ho_1: call ch_out
363			pop ax
364			loop ho_loop
365
366			push ax
367			mov al, #0x20
368			call ch_out
369			pop ax
370
371			ret
372
373			!******************************************************
374			!** D A T A ***************************************
375			!******************************************************
376
377			gdt_len: dw 0
378			gdt_base: dd 0
379
380			kernel_version: .ascii "Linux "
381			.ascii " " ; version goes here
382			.byte 0x0
383
384			start_linux: .word 0x0a0d
385			.ascii "Starting Linux..."
386			.word 0x0a0d
387			.byte 0x0
388
389			params_head: .ascii "Kernel parameters: "
390			.byte 0x0
391
392			memcount_msg: .ascii "Counting memory... "
393			.byte 0x0
394
395			rdmove_msg: .ascii "Moving initrd... "
396			.byte 0x0
397
398			.align 16
399
400			gdt: .word 0,0,0,0
401			.word 0,0,0,0
402
403			.word 0xFFFF ! 4Gb - (0x100000*0x1000 = 4Gb)
404			.word 0x0000 ! base address=0
405			.word 0x9A00 ! code read/exec
406			.word 0x00CF ! granularity=4096, 386 (+5th nibble of limit)
407
408			.word 0xFFFF ! 4Gb - (0x100000*0x1000 = 4Gb)
409			.word 0x0000 ! base address=0
410			.word 0x9200 ! data read/write
411			.word 0x00CF ! granularity=4096, 386 (+5th nibble of limit)
412			gdt_end: .word 0
413
414			idt_48: .word 0 ! idt limit=0
415			.long 0 ! idt base=0L
416
417			gdt_48: .word gdt_end-gdt !
418			.long 0x90000+gdt ! gdt base = 0X9xxxx
419
420
421			.byte 0x0
422			kernelparam: ;.ascii "console=ttyS0,38400N8"
423			; .ascii " root=/dev/ram0 rw "
424			.ascii " root=/dev/sda1 lang=us quiet tz=Europe/Amsterdam"
425			.ascii " video=nscfb:vmode:1024x768-16,vfreq:75 splash=silent"
426			.ascii " reboot=bios"
427			.byte 0x0
428
429
430			!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
431
432			setup_sig1: .word 0xAA55
433			setup_sig2: .word 0x5A5A
434
435			eof: