1#
2# Copyright (c) 1998 Robert Nordier
3# All rights reserved.
4#
5# Redistribution and use in source and binary forms are freely
6# permitted provided that the above copyright notice and this
7# paragraph and the following disclaimer are duplicated in all
8# such forms.
9#
10# This software is provided "AS IS" and without any express or
11# implied warranties, including, without limitation, the implied
12# warranties of merchantability and fitness for a particular
13# purpose.
14#
15
| 1#
2# Copyright (c) 1998 Robert Nordier
3# All rights reserved.
4#
5# Redistribution and use in source and binary forms are freely
6# permitted provided that the above copyright notice and this
7# paragraph and the following disclaimer are duplicated in all
8# such forms.
9#
10# This software is provided "AS IS" and without any express or
11# implied warranties, including, without limitation, the implied
12# warranties of merchantability and fitness for a particular
13# purpose.
14#
15
|
16# $FreeBSD: head/sys/boot/i386/boot2/boot1.S 50477 1999-08-28 01:08:13Z peter $
| 16# $FreeBSD: head/sys/boot/i386/boot2/boot1.S 60821 2000-05-23 12:18:49Z jhb $
|
17
18 .set MEM_REL,0x700 # Relocation address
19 .set MEM_ARG,0x900 # Arguments
20 .set MEM_ORG,0x7c00 # Origin
21 .set MEM_BUF,0x8c00 # Load area
22 .set MEM_BTX,0x9000 # BTX start
23 .set MEM_JMP,0x9010 # BTX entry point
24 .set MEM_USR,0xa000 # Client start
25
26 .set PRT_OFF,0x1be # Partition offset
27 .set PRT_NUM,0x4 # Partitions
28 .set PRT_BSD,0xa5 # Partition type
29
30 .set SIZ_PAG,0x1000 # Page size
31 .set SIZ_SEC,0x200 # Sector size
32
33 .globl start
34 .globl xread
| 17
18 .set MEM_REL,0x700 # Relocation address
19 .set MEM_ARG,0x900 # Arguments
20 .set MEM_ORG,0x7c00 # Origin
21 .set MEM_BUF,0x8c00 # Load area
22 .set MEM_BTX,0x9000 # BTX start
23 .set MEM_JMP,0x9010 # BTX entry point
24 .set MEM_USR,0xa000 # Client start
25
26 .set PRT_OFF,0x1be # Partition offset
27 .set PRT_NUM,0x4 # Partitions
28 .set PRT_BSD,0xa5 # Partition type
29
30 .set SIZ_PAG,0x1000 # Page size
31 .set SIZ_SEC,0x200 # Sector size
32
33 .globl start
34 .globl xread
|
| 35 .code16
|
35
36start: jmp main # Start recognizably
37
38 .org 0x4,0x90
39
40# External read from disk
41
| 36
37start: jmp main # Start recognizably
38
39 .org 0x4,0x90
40
41# External read from disk
42
|
42xread: pushl %ss # Address
43 popl %ds # data
44xread.1: o16 # Starting
45 pushb $0x0 # absolute
46 pushl %ecx # block
47 pushl %eax # number
48 pushl %es # Address of
49 pushl %ebx # transfer buffer
50 xorl %eax,%eax # Number of
| 43xread: push %ss # Address
44 pop %ds # data
45xread.1: # Starting
46 pushl $0x0 # absolute
47 push %cx # block
48 push %ax # number
49 push %es # Address of
50 push %bx # transfer buffer
51 xor %ax,%ax # Number of
|
51 movb %dh,%al # blocks to
| 52 movb %dh,%al # blocks to
|
52 pushl %eax # transfer
53 pushb $0x10 # Size of packet
54 movl %esp,%ebp # Packet pointer
55 callwi(read) # Read from disk
56 leaw1r(0x10,_bp_,_sp) # Clear stack
| 53 push %ax # transfer
54 push $0x10 # Size of packet
55 mov %sp,%bp # Packet pointer
56 callw read # Read from disk
57 lea 0x10(%bp),%sp # Clear stack
|
57 lret # To far caller
58
59# Bootstrap
60
61main: cld # String ops inc
| 58 lret # To far caller
59
60# Bootstrap
61
62main: cld # String ops inc
|
62 xorl %ecx,%ecx # Zero
63 movl %cx,%es # Address
64 movl %cx,%ds # data
65 movl %cx,%ss # Set up
66 movwir(start,_sp) # stack
67 movl %esp,%esi # Source
68 movwir(MEM_REL,_di) # Destination
| 63 xor %cx,%cx # Zero
64 mov %cx,%es # Address
65 mov %cx,%ds # data
66 mov %cx,%ss # Set up
67 mov $start,%sp # stack
68 mov %sp,%si # Source
69 mov $MEM_REL,%di # Destination
|
69 incb %ch # Word count
70 rep # Copy
| 70 incb %ch # Word count
71 rep # Copy
|
71 movsl # code
72 movwir(part4,_si) # Partition
| 72 movsw # code
73 mov $part4,%si # Partition
|
73 cmpb $0x80,%dl # Hard drive?
74 jb main.4 # No
75 movb $0x1,%dh # Block count
| 74 cmpb $0x80,%dl # Hard drive?
75 jb main.4 # No
76 movb $0x1,%dh # Block count
|
76 callwi(nread) # Read MBR
77 movwir(0x1,_cx) # Two passes
78main.1: movwir(MEM_BUF+PRT_OFF,_si) # Partition table
| 77 callw nread # Read MBR
78 mov $0x1,%cx # Two passes
79main.1: mov $MEM_BUF+PRT_OFF,%si # Partition table
|
79 movb $0x1,%dh # Partition
| 80 movb $0x1,%dh # Partition
|
80main.2: cmpbi1(PRT_BSD,0x4,_si_) # Our partition type?
| 81main.2: cmpb $PRT_BSD,0x4(%si) # Our partition type?
|
81 jne main.3 # No
| 82 jne main.3 # No
|
82 jecxz main.5 # If second pass
83 tstbi0(0x80,_si_) # Active?
| 83 jcxz main.5 # If second pass
84 testb $0x80,(%si) # Active?
|
84 jnz main.5 # Yes
| 85 jnz main.5 # Yes
|
85main.3: addl $0x10,%esi # Next entry
| 86main.3: add $0x10,%si # Next entry
|
86 incb %dh # Partition
87 cmpb $0x1+PRT_NUM,%dh # In table?
88 jb main.2 # Yes
| 87 incb %dh # Partition
88 cmpb $0x1+PRT_NUM,%dh # In table?
89 jb main.2 # Yes
|
89 decl %ecx # Do two
90 jecxz main.1 # passes
91 movwir(msg_part,_si) # Message
| 90 dec %cx # Do two
91 jcxz main.1 # passes
92 mov $msg_part,%si # Message
|
92 jmp error # Error
| 93 jmp error # Error
|
93main.4: xorl %edx,%edx # Partition:drive
94main.5: movwrm(_dx,MEM_ARG) # Save args
| 94main.4: xor %dx,%dx # Partition:drive
95main.5: mov %dx,MEM_ARG # Save args
|
95 movb $0x10,%dh # Sector count
| 96 movb $0x10,%dh # Sector count
|
96 callwi(nread) # Read disk
97 movwir(MEM_BTX,_bx) # BTX
98 movw1r(0xa,_bx_,_si) # Point past
99 addl %ebx,%esi # it
100 movwir(MEM_USR+SIZ_PAG,_di) # Client page 1
101 movwir(MEM_BTX+0xe*SIZ_SEC,_cx) # Byte
102 subl %esi,%ecx # count
| 97 callw nread # Read disk
98 mov $MEM_BTX,%bx # BTX
99 mov 0xa(%bx),%si # Point past
100 add %bx,%si # it
101 mov $MEM_USR+SIZ_PAG,%di # Client page 1
102 mov $MEM_BTX+0xe*SIZ_SEC,%cx # Byte
103 sub %si,%cx # count
|
103 rep # Relocate
104 movsb # client
| 104 rep # Relocate
105 movsb # client
|
105 subl %edi,%ecx # Byte count
| 106 sub %di,%cx # Byte count
|
106 xorb %al,%al # Zero
107 rep # assumed
108 stosb # bss
| 107 xorb %al,%al # Zero
108 rep # assumed
109 stosb # bss
|
109 callwi(seta20) # Enable A20
110 jmpnwi(start+MEM_JMP-MEM_ORG) # Start BTX
| 110 callw seta20 # Enable A20
111 jmp start+MEM_JMP-MEM_ORG # Start BTX
|
111
112# Enable A20
113
114seta20: cli # Disable interrupts
115seta20.1: inb $0x64,%al # Get status
116 testb $0x2,%al # Busy?
117 jnz seta20.1 # Yes
118 movb $0xd1,%al # Command: Write
119 outb %al,$0x64 # output port
120seta20.2: inb $0x64,%al # Get status
121 testb $0x2,%al # Busy?
122 jnz seta20.2 # Yes
123 movb $0xdf,%al # Enable
124 outb %al,$0x60 # A20
125 sti # Enable interrupts
| 112
113# Enable A20
114
115seta20: cli # Disable interrupts
116seta20.1: inb $0x64,%al # Get status
117 testb $0x2,%al # Busy?
118 jnz seta20.1 # Yes
119 movb $0xd1,%al # Command: Write
120 outb %al,$0x64 # output port
121seta20.2: inb $0x64,%al # Get status
122 testb $0x2,%al # Busy?
123 jnz seta20.2 # Yes
124 movb $0xdf,%al # Enable
125 outb %al,$0x60 # A20
126 sti # Enable interrupts
|
126 ret # To caller
| 127 retw # To caller
|
127
128# Local read from disk
129
| 128
129# Local read from disk
130
|
130nread: movwir(MEM_BUF,_bx) # Transfer buffer
131 movw1r(0x8,_si_,_ax) # Get
132 movw1r(0xa,_si_,_cx) # LBA
133 pushl %cs # Read from
134 callwi(xread.1) # disk
| 131nread: mov $MEM_BUF,%bx # Transfer buffer
132 mov 0x8(%si),%ax # Get
133 mov 0xa(%si),%cx # LBA
134 push %cs # Read from
135 callw xread.1 # disk
|
135 jnc return # If success
| 136 jnc return # If success
|
136 movwir(msg_read,_si) # Message
| 137 mov $msg_read,%si # Message
|
137
138# Error exit
139
| 138
139# Error exit
140
|
140error: callwi(putstr) # Display message
141 movwir(prompt,_si) # Display
142 callwi(putstr) # prompt
| 141error: callw putstr # Display message
142 mov $prompt,%si # Display
143 callw putstr # prompt
|
143 xorb %ah,%ah # BIOS: Get
144 int $0x16 # keypress
145 int $0x19 # BIOS: Reboot
146
147# Display string
148
| 144 xorb %ah,%ah # BIOS: Get
145 int $0x16 # keypress
146 int $0x19 # BIOS: Reboot
147
148# Display string
149
|
149putstr.0: movwir(0x7,_bx) # Page:attribute
| 150putstr.0: mov $0x7,%bx # Page:attribute
|
150 movb $0xe,%ah # BIOS: Display
151 int $0x10 # character
152putstr: lodsb # Get char
153 testb %al,%al # End of string?
154 jne putstr.0 # No
155
156ereturn: movb $0x1,%ah # Invalid
157 stc # argument
| 151 movb $0xe,%ah # BIOS: Display
152 int $0x10 # character
153putstr: lodsb # Get char
154 testb %al,%al # End of string?
155 jne putstr.0 # No
156
157ereturn: movb $0x1,%ah # Invalid
158 stc # argument
|
158return: ret # To caller
| 159return: retw # To caller
|
159
160# Read from disk
161
| 160
161# Read from disk
162
|
162read: cs_ # LBA support
163 tstbim(0x80,MEM_REL+flags-start)# enabled?
| 163read: testb $0x80,%cs:MEM_REL+flags-start # LBA support enabled?
|
164 jz read.1 # No
| 164 jz read.1 # No
|
165 movwir(0x55aa,_bx) # Magic
166 pushl %edx # Save
| 165 mov $0x55aa,%bx # Magic
166 push %dx # Save
|
167 movb $0x41,%ah # BIOS: Check
168 int $0x13 # extensions present
| 167 movb $0x41,%ah # BIOS: Check
168 int $0x13 # extensions present
|
169 popl %edx # Restore
| 169 pop %dx # Restore
|
170 jc read.1 # If error
| 170 jc read.1 # If error
|
171 cmpwir(0xaa55,_bx) # Magic?
| 171 cmp $0xaa55,%bx # Magic?
|
172 jne read.1 # No
173 testb $0x1,%cl # Packet interface?
174 jz read.1 # No
| 172 jne read.1 # No
173 testb $0x1,%cl # Packet interface?
174 jz read.1 # No
|
175 movl %ebp,%esi # Disk packet
| 175 mov %bp,%si # Disk packet
|
176 movb $0x42,%ah # BIOS: Extended
177 int $0x13 # read
| 176 movb $0x42,%ah # BIOS: Extended
177 int $0x13 # read
|
178 ret # To caller
| 178 retw # To caller
|
179
| 179
|
180read.1: pushl %edx # Save
| 180read.1: push %dx # Save
|
181 movb $0x8,%ah # BIOS: Get drive
182 int $0x13 # parameters
183 movb %dh,%ch # Max head number
| 181 movb $0x8,%ah # BIOS: Get drive
182 int $0x13 # parameters
183 movb %dh,%ch # Max head number
|
184 popl %edx # Restore
| 184 pop %dx # Restore
|
185 jc return # If error
186 andb $0x3f,%cl # Sectors per track
187 jz ereturn # If zero
188 cli # Disable interrupts
| 185 jc return # If error
186 andb $0x3f,%cl # Sectors per track
187 jz ereturn # If zero
188 cli # Disable interrupts
|
189 o16 # Get
190 movw1r(0x8,_bp_,_ax) # LBA
191 pushl %edx # Save
192 movzbw %cl,%bx # Divide by
193 xorw %dx,%dx # sectors
194 divw %bx,%ax # per track
| 189 mov 0x8(%bp),%eax # Get LBA
190 push %dx # Save
191 movzbl %cl,%ebx # Divide by
192 xor %edx,%edx # sectors
193 div %ebx # per track
|
195 movb %ch,%bl # Max head number
196 movb %dl,%ch # Sector number
| 194 movb %ch,%bl # Max head number
195 movb %dl,%ch # Sector number
|
197 incl %ebx # Divide by
| 196 inc %bx # Divide by
|
198 xorb %dl,%dl # number
| 197 xorb %dl,%dl # number
|
199 divw %bx,%ax # of heads
| 198 div %ebx # of heads
|
200 movb %dl,%bh # Head number
| 199 movb %dl,%bh # Head number
|
201 popl %edx # Restore
202 o16 # Cylinder number
203 cmpl $0x3ff,%eax # supportable?
| 200 pop %dx # Restore
201 cmpl $0x3ff,%eax # Cylinder number supportable?
|
204 sti # Enable interrupts
205 ja ereturn # No
206 xchgb %al,%ah # Set up cylinder
207 rorb $0x2,%al # number
208 orb %ch,%al # Merge
| 202 sti # Enable interrupts
203 ja ereturn # No
204 xchgb %al,%ah # Set up cylinder
205 rorb $0x2,%al # number
206 orb %ch,%al # Merge
|
209 incl %eax # sector
210 xchgl %eax,%ecx # number
| 207 inc %ax # sector
208 xchg %ax,%cx # number
|
211 movb %bh,%dh # Head number
212 subb %ah,%al # Sectors this track
| 209 movb %bh,%dh # Head number
210 subb %ah,%al # Sectors this track
|
213 movb1r(0x2,_bp_,_ah) # Blocks to read
| 211 mov 0x2(%bp),%ah # Blocks to read
|
214 cmpb %ah,%al # To read
215 jb read.2 # this
216 movb %ah,%al # track
| 212 cmpb %ah,%al # To read
213 jb read.2 # this
214 movb %ah,%al # track
|
217read.2: movwir(0x5,_di) # Try count
218read.3: lesw1r(0x4,_bp_,_bx) # Transfer buffer
219 pushl %eax # Save
| 215read.2: mov $0x5,%di # Try count
216read.3: les 0x4(%bp),%bx # Transfer buffer
217 push %ax # Save
|
220 movb $0x2,%ah # BIOS: Read
221 int $0x13 # from disk
| 218 movb $0x2,%ah # BIOS: Read
219 int $0x13 # from disk
|
222 popl %ebx # Restore
| 220 pop %bx # Restore
|
223 jnc read.4 # If success
| 221 jnc read.4 # If success
|
224 decl %edi # Retry?
| 222 dec %di # Retry?
|
225 jz read.6 # No
226 xorb %ah,%ah # BIOS: Reset
227 int $0x13 # disk system
| 223 jz read.6 # No
224 xorb %ah,%ah # BIOS: Reset
225 int $0x13 # disk system
|
228 xchgl %ebx,%eax # Block count
| 226 xchg %bx,%ax # Block count
|
229 jmp read.3 # Continue
| 227 jmp read.3 # Continue
|
230read.4: movzbl %bl,%eax # Sectors read
231 addwr1(_ax,0x8,_bp_) # Adjust
| 228read.4: movzbw %bl,%ax # Sectors read
229 add %ax,0x8(%bp) # Adjust
|
232 jnc read.5 # LBA,
| 230 jnc read.5 # LBA,
|
233 incw1(0xa,_bp_) # transfer
| 231 incw 0xa(%bp) # transfer
|
234read.5: shlb %bl # buffer
| 232read.5: shlb %bl # buffer
|
235 addbr1(_bl,0x5,_bp_) # pointer,
236 subbr1(_al,0x2,_bp_) # block count
| 233 add %bl,0x5(%bp) # pointer,
234 sub %al,0x2(%bp) # block count
|
237 ja read.1 # If not done
| 235 ja read.1 # If not done
|
238read.6: ret # To caller
| 236read.6: retw # To caller
|
239
240# Messages
241
242msg_read: .asciz "Read"
243msg_part: .asciz "Boot"
244
245prompt: .asciz " error\r\n"
246
--- 13 unchanged lines hidden --- | 237
238# Messages
239
240msg_read: .asciz "Read"
241msg_part: .asciz "Boot"
242
243prompt: .asciz " error\r\n"
244
--- 13 unchanged lines hidden --- |