1/* 2 * Copyright (c) 2000 John Baldwin 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 *
| 1/* 2 * Copyright (c) 2000 John Baldwin 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 *
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15 * $FreeBSD: head/sys/boot/i386/pxeldr/pxeldr.S 128716 2004-04-28 14:31:44Z ru $
| 15 * $FreeBSD: head/sys/boot/i386/pxeldr/pxeldr.S 129240 2004-05-14 20:29:30Z ru $
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16 */ 17 18/* 19 * This simple program is a preloader for the normal boot3 loader. It is simply 20 * prepended to the beginning of a fully built and btxld'd loader. It then 21 * copies the loader to the address boot2 normally loads it, emulates the
| 16 */ 17 18/* 19 * This simple program is a preloader for the normal boot3 loader. It is simply 20 * prepended to the beginning of a fully built and btxld'd loader. It then 21 * copies the loader to the address boot2 normally loads it, emulates the
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22 * boot[12] environment (protected mode, a bootinfo struct, etc.) and then jumps
| 22 * boot[12] environment (protected mode, a bootinfo struct, etc.), and then jumps
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23 * to the start of btxldr to start the boot process. This method allows a stock 24 * /boot/loader to be booted over the network via PXE w/o having to write a 25 * separate PXE-aware client just to load the loader. 26 */ 27 28/* 29 * Memory locations. 30 */
| 23 * to the start of btxldr to start the boot process. This method allows a stock 24 * /boot/loader to be booted over the network via PXE w/o having to write a 25 * separate PXE-aware client just to load the loader. 26 */ 27 28/* 29 * Memory locations. 30 */
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31 .set MEM_PAGE_SIZE,0x1000 // memory page size, 4k 32 .set MEM_ARG,0x900 // Arguments at start 33 .set MEM_ARG_BTX,0xa100 // Where we move them to so the 34 // BTX client can see them 35 .set MEM_ARG_SIZE,0x18 // Size of the arguments 36 .set MEM_BTX_ADDRESS,0x9000 // where BTX lives 37 .set MEM_BTX_ENTRY,0x9010 // where BTX starts to execute 38 .set MEM_BTX_OFFSET,MEM_PAGE_SIZE // offset of BTX in the loader 39 .set MEM_BTX_CLIENT,0xa000 // where BTX clients live 40 .set MEM_BIOS_KEYBOARD,0x496 // BDA byte with keyboard bit
| 31 .set MEM_PAGE_SIZE,0x1000 # memory page size, 4k 32 .set MEM_ARG,0x900 # Arguments at start 33 .set MEM_ARG_BTX,0xa100 # Where we move them to so the 34 # BTX client can see them 35 .set MEM_ARG_SIZE,0x18 # Size of the arguments 36 .set MEM_BTX_ADDRESS,0x9000 # where BTX lives 37 .set MEM_BTX_ENTRY,0x9010 # where BTX starts to execute 38 .set MEM_BTX_OFFSET,MEM_PAGE_SIZE # offset of BTX in the loader 39 .set MEM_BTX_CLIENT,0xa000 # where BTX clients live 40 .set MEM_BIOS_KEYBOARD,0x496 # BDA byte with keyboard bit
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41/* 42 * a.out header fields 43 */
| 41/* 42 * a.out header fields 43 */
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44 .set AOUT_TEXT,0x04 // text segment size 45 .set AOUT_DATA,0x08 // data segment size 46 .set AOUT_BSS,0x0c // zero'd BSS size 47 .set AOUT_SYMBOLS,0x10 // symbol table 48 .set AOUT_ENTRY,0x14 // entry point 49 .set AOUT_HEADER,MEM_PAGE_SIZE // size of the a.out header
| 44 .set AOUT_TEXT,0x04 # text segment size 45 .set AOUT_DATA,0x08 # data segment size 46 .set AOUT_BSS,0x0c # zero'd BSS size 47 .set AOUT_SYMBOLS,0x10 # symbol table 48 .set AOUT_ENTRY,0x14 # entry point 49 .set AOUT_HEADER,MEM_PAGE_SIZE # size of the a.out header
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50/* 51 * Flags for kargs->bootflags 52 */
| 50/* 51 * Flags for kargs->bootflags 52 */
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53 .set KARGS_FLAGS_PXE,0x2 // flag to indicate booting from 54 // PXE loader
| 53 .set KARGS_FLAGS_PXE,0x2 # flag to indicate booting from 54 # PXE loader
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55/* 56 * Boot howto bits 57 */
| 55/* 56 * Boot howto bits 57 */
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58 .set RB_SERIAL,0x1000 // serial console
| 58 .set RB_SERIAL,0x1000 # serial console
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59/* 60 * Segment selectors. 61 */
| 59/* 60 * Segment selectors. 61 */
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62 .set SEL_SDATA,0x8 // Supervisor data 63 .set SEL_RDATA,0x10 // Real mode data 64 .set SEL_SCODE,0x18 // PM-32 code 65 .set SEL_SCODE16,0x20 // PM-16 code
| 62 .set SEL_SDATA,0x8 # Supervisor data 63 .set SEL_RDATA,0x10 # Real mode data 64 .set SEL_SCODE,0x18 # PM-32 code 65 .set SEL_SCODE16,0x20 # PM-16 code
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66/* 67 * BTX constants 68 */
| 66/* 67 * BTX constants 68 */
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69 .set INT_SYS,0x30 // BTX syscall interrupt
| 69 .set INT_SYS,0x30 # BTX syscall interrupt
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70/* 71 * Bit in MEM_BIOS_KEYBOARD that is set if an enhanced keyboard is present 72 */ 73 .set KEYBOARD_BIT,0x10 74/* 75 * We expect to be loaded by the BIOS at 0x7c00 (standard boot loader entry 76 * point) 77 */ 78 .code16 79 .globl start 80 .org 0x0, 0x0 81/* 82 * BTX program loader for PXE network booting 83 */
| 70/* 71 * Bit in MEM_BIOS_KEYBOARD that is set if an enhanced keyboard is present 72 */ 73 .set KEYBOARD_BIT,0x10 74/* 75 * We expect to be loaded by the BIOS at 0x7c00 (standard boot loader entry 76 * point) 77 */ 78 .code16 79 .globl start 80 .org 0x0, 0x0 81/* 82 * BTX program loader for PXE network booting 83 */
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84start: cld // string ops inc 85 xorw %ax, %ax // zero %ax 86 movw %ax, %ss // setup the 87 movw $start, %sp // stack 88 movw %es, %cx // save PXENV+ segment 89 movw %ax, %ds // setup the 90 movw %ax, %es // data segments 91 andl $0xffff, %ecx // clear upper words 92 andl $0xffff, %ebx // of %ebx and %ecx 93 shll $4, %ecx // calculate the offset of 94 addl %ebx, %ecx // the PXENV+ struct and 95 pushl %ecx // save it on the stack 96 movw $welcome_msg, %si // %ds:(%si) -> welcome message 97 callw putstr // display the welcome message
| 84start: cld # string ops inc 85 xorw %ax, %ax # zero %ax 86 movw %ax, %ss # setup the 87 movw $start, %sp # stack 88 movw %es, %cx # save PXENV+ segment 89 movw %ax, %ds # setup the 90 movw %ax, %es # data segments 91 andl $0xffff, %ecx # clear upper words 92 andl $0xffff, %ebx # of %ebx and %ecx 93 shll $4, %ecx # calculate the offset of 94 addl %ebx, %ecx # the PXENV+ struct and 95 pushl %ecx # save it on the stack 96 movw $welcome_msg, %si # %ds:(%si) -> welcome message 97 callw putstr # display the welcome message
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98/* 99 * Setup the arguments that the loader is expecting from boot[12] 100 */
| 98/* 99 * Setup the arguments that the loader is expecting from boot[12] 100 */
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101 movw $bootinfo_msg, %si // %ds:(%si) -> boot args 102 // message 103 callw putstr // display the message 104 movw $MEM_ARG, %bx // %ds:(%bx) -> boot args 105 movw %bx, %di // %es:(%di) -> boot args 106 xorl %eax, %eax // zero %eax 107 movw $(MEM_ARG_SIZE/4), %cx // Size of arguments in 32-bit 108 // dwords 109 rep // Clear the arguments 110 stosl // to zero 111 orb $KARGS_FLAGS_PXE, 0x8(%bx) // kargs->bootflags |= 112 // KARGS_FLAGS_PXE 113 popl 0xc(%bx) // kargs->pxeinfo = *PXENV+
| 101 movw $bootinfo_msg, %si # %ds:(%si) -> boot args message 102 callw putstr # display the message 103 movw $MEM_ARG, %bx # %ds:(%bx) -> boot args 104 movw %bx, %di # %es:(%di) -> boot args 105 xorl %eax, %eax # zero %eax 106 movw $(MEM_ARG_SIZE/4), %cx # Size of arguments in 32-bit 107 # dwords 108 rep # Clear the arguments 109 stosl # to zero 110 orb $KARGS_FLAGS_PXE, 0x8(%bx) # kargs->bootflags |= 111 # KARGS_FLAGS_PXE 112 popl 0xc(%bx) # kargs->pxeinfo = *PXENV+
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114#ifdef ALWAYS_SERIAL 115/* 116 * set the RBX_SERIAL bit in the howto byte. 117 */
| 113#ifdef ALWAYS_SERIAL 114/* 115 * set the RBX_SERIAL bit in the howto byte. 116 */
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118 orl $RB_SERIAL, (%bx) // enable serial console
| 117 orl $RB_SERIAL, (%bx) # enable serial console
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119#endif 120#ifdef PROBE_KEYBOARD 121/* 122 * Look at the BIOS data area to see if we have an enhanced keyboard. If not, 123 * set the RBX_SERIAL bit in the howto byte. 124 */
| 118#endif 119#ifdef PROBE_KEYBOARD 120/* 121 * Look at the BIOS data area to see if we have an enhanced keyboard. If not, 122 * set the RBX_SERIAL bit in the howto byte. 123 */
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125 testb $KEYBOARD_BIT, MEM_BIOS_KEYBOARD // keyboard present? 126 jnz keyb // yes, so skip 127 orl $RB_SERIAL, (%bx) // enable serial console
| 124 testb $KEYBOARD_BIT, MEM_BIOS_KEYBOARD # keyboard present? 125 jnz keyb # yes, so skip 126 orl $RB_SERIAL, (%bx) # enable serial console
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128keyb: 129#endif 130/* 131 * Turn on the A20 address line 132 */
| 127keyb: 128#endif 129/* 130 * Turn on the A20 address line 131 */
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133 callw seta20 // Turn A20 on
| 132 callw seta20 # Turn A20 on
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134/* 135 * Relocate the loader and BTX using a very lazy protected mode 136 */
| 133/* 134 * Relocate the loader and BTX using a very lazy protected mode 135 */
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137 movw $relocate_msg, %si // Display the 138 callw putstr // relocation message 139 movl end+AOUT_ENTRY, %edi // %edi is the destination 140 movl $(end+AOUT_HEADER), %esi // %esi is 141 // the start of the text 142 // segment 143 movl end+AOUT_TEXT, %ecx // %ecx = length of the text 144 // segment 145 lgdt gdtdesc // setup our own gdt 146 cli // turn off interrupts 147 movl %cr0, %eax // Turn on 148 orb $0x1, %al // protected 149 movl %eax, %cr0 // mode 150 ljmp $SEL_SCODE,$pm_start // long jump to clear the 151 // instruction pre-fetch queue
| 136 movw $relocate_msg, %si # Display the 137 callw putstr # relocation message 138 movl end+AOUT_ENTRY, %edi # %edi is the destination 139 movl $(end+AOUT_HEADER), %esi # %esi is 140 # the start of the text 141 # segment 142 movl end+AOUT_TEXT, %ecx # %ecx = length of the text 143 # segment 144 lgdt gdtdesc # setup our own gdt 145 cli # turn off interrupts 146 movl %cr0, %eax # Turn on 147 orb $0x1, %al # protected 148 movl %eax, %cr0 # mode 149 ljmp $SEL_SCODE,$pm_start # long jump to clear the 150 # instruction pre-fetch queue
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152 .code32
| 151 .code32
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153pm_start: movw $SEL_SDATA, %ax // Initialize 154 movw %ax, %ds // %ds and 155 movw %ax, %es // %es to a flat selector 156 rep // Relocate the 157 movsb // text segment 158 addl $(MEM_PAGE_SIZE - 1), %edi // pad %edi out to a new page 159 andl $~(MEM_PAGE_SIZE - 1), %edi // for the data segment 160 movl end+AOUT_DATA, %ecx // size of the data segment 161 rep // Relocate the 162 movsb // data segment 163 movl end+AOUT_BSS, %ecx // size of the bss 164 xorl %eax, %eax // zero %eax 165 addb $3, %cl // round %ecx up to 166 shrl $2, %ecx // a multiple of 4 167 rep // zero the 168 stosl // bss 169 movl end+AOUT_ENTRY, %esi // %esi -> relocated loader 170 addl $MEM_BTX_OFFSET, %esi // %esi -> BTX in the loader 171 movl $MEM_BTX_ADDRESS, %edi // %edi -> where BTX needs to go 172 movzwl 0xa(%esi), %ecx // %ecx -> length of BTX 173 rep // Relocate 174 movsb // BTX 175 ljmp $SEL_SCODE16,$pm_16 // Jump to 16-bit PM
| 152pm_start: movw $SEL_SDATA, %ax # Initialize 153 movw %ax, %ds # %ds and 154 movw %ax, %es # %es to a flat selector 155 rep # Relocate the 156 movsb # text segment 157 addl $(MEM_PAGE_SIZE - 1), %edi # pad %edi out to a new page 158 andl $~(MEM_PAGE_SIZE - 1), %edi # for the data segment 159 movl end+AOUT_DATA, %ecx # size of the data segment 160 rep # Relocate the 161 movsb # data segment 162 movl end+AOUT_BSS, %ecx # size of the bss 163 xorl %eax, %eax # zero %eax 164 addb $3, %cl # round %ecx up to 165 shrl $2, %ecx # a multiple of 4 166 rep # zero the 167 stosl # bss 168 movl end+AOUT_ENTRY, %esi # %esi -> relocated loader 169 addl $MEM_BTX_OFFSET, %esi # %esi -> BTX in the loader 170 movl $MEM_BTX_ADDRESS, %edi # %edi -> where BTX needs to go 171 movzwl 0xa(%esi), %ecx # %ecx -> length of BTX 172 rep # Relocate 173 movsb # BTX 174 ljmp $SEL_SCODE16,$pm_16 # Jump to 16-bit PM
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176 .code16
| 175 .code16
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177pm_16: movw $SEL_RDATA, %ax // Initialize 178 movw %ax, %ds // %ds and 179 movw %ax, %es // %es to a real mode selector 180 movl %cr0, %eax // Turn off 181 andb $~0x1, %al // protected 182 movl %eax, %cr0 // mode 183 ljmp $0,$pm_end // Long jump to clear the 184 // instruction pre-fetch queue 185pm_end: sti // Turn interrupts back on now
| 176pm_16: movw $SEL_RDATA, %ax # Initialize 177 movw %ax, %ds # %ds and 178 movw %ax, %es # %es to a real mode selector 179 movl %cr0, %eax # Turn off 180 andb $~0x1, %al # protected 181 movl %eax, %cr0 # mode 182 ljmp $0,$pm_end # Long jump to clear the 183 # instruction pre-fetch queue 184pm_end: sti # Turn interrupts back on now
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186/* 187 * Copy the BTX client to MEM_BTX_CLIENT 188 */
| 185/* 186 * Copy the BTX client to MEM_BTX_CLIENT 187 */
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189 xorw %ax, %ax // zero %ax and set 190 movw %ax, %ds // %ds and %es 191 movw %ax, %es // to segment 0 192 movw $MEM_BTX_CLIENT, %di // Prepare to relocate 193 movw $btx_client, %si // the simple btx client 194 movw $(btx_client_end-btx_client), %cx // length of btx client 195 rep // Relocate the 196 movsb // simple BTX client
| 188 xorw %ax, %ax # zero %ax and set 189 movw %ax, %ds # %ds and %es 190 movw %ax, %es # to segment 0 191 movw $MEM_BTX_CLIENT, %di # Prepare to relocate 192 movw $btx_client, %si # the simple btx client 193 movw $(btx_client_end-btx_client), %cx # length of btx client 194 rep # Relocate the 195 movsb # simple BTX client
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197/* 198 * Copy the boot[12] args to where the BTX client can see them 199 */
| 196/* 197 * Copy the boot[12] args to where the BTX client can see them 198 */
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200 movw $MEM_ARG, %si // where the args are at now 201 movw $MEM_ARG_BTX, %di // where the args are moving to 202 movw $(MEM_ARG_SIZE/4), %cx // size of the arguments in 203 // longs 204 rep // Relocate 205 movsl // the words
| 199 movw $MEM_ARG, %si # where the args are at now 200 movw $MEM_ARG_BTX, %di # where the args are moving to 201 movw $(MEM_ARG_SIZE/4), %cx # size of the arguments in longs 202 rep # Relocate 203 movsl # the words
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206/* 207 * Save the entry point so the client can get to it later on 208 */
| 204/* 205 * Save the entry point so the client can get to it later on 206 */
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209 movl end+AOUT_ENTRY, %eax // load the entry point 210 stosl // add it to the end of the 211 // arguments
| 207 movl end+AOUT_ENTRY, %eax # load the entry point 208 stosl # add it to the end of the 209 # arguments
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212/* 213 * Now we just start up BTX and let it do the rest 214 */
| 210/* 211 * Now we just start up BTX and let it do the rest 212 */
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215 movw $jump_message, %si // Display the 216 callw putstr // jump message 217 ljmp $0,$MEM_BTX_ENTRY // Jump to the BTX entry point
| 213 movw $jump_message, %si # Display the 214 callw putstr # jump message 215 ljmp $0,$MEM_BTX_ENTRY # Jump to the BTX entry point
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218 219/* 220 * Display a null-terminated string 221 */
| 216 217/* 218 * Display a null-terminated string 219 */
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222putstr: lodsb // load %al from %ds:(%si) 223 testb %al,%al // stop at null 224 jnz putc // if the char != null, 225 // output it 226 retw // return when null is hit 227putc: movw $0x7,%bx // attribute for output 228 movb $0xe,%ah // BIOS: put_char 229 int $0x10 // call BIOS, print char in %al 230 jmp putstr // keep looping
| 220putstr: lodsb # load %al from %ds:(%si) 221 testb %al,%al # stop at null 222 jnz putc # if the char != null, output it 223 retw # return when null is hit 224putc: movw $0x7,%bx # attribute for output 225 movb $0xe,%ah # BIOS: put_char 226 int $0x10 # call BIOS, print char in %al 227 jmp putstr # keep looping
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231 232/* 233 * Enable A20 234 */
| 228 229/* 230 * Enable A20 231 */
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235seta20: cli // Disable interrupts 236seta20.1: inb $0x64,%al // Get status 237 testb $0x2,%al // Busy? 238 jnz seta20.1 // Yes 239 movb $0xd1,%al // Command: Write 240 outb %al,$0x64 // output port 241seta20.2: inb $0x64,%al // Get status 242 testb $0x2,%al // Busy? 243 jnz seta20.2 // Yes 244 movb $0xdf,%al // Enable 245 outb %al,$0x60 // A20 246 sti // Enable interrupts 247 retw // To caller
| 232seta20: cli # Disable interrupts 233seta20.1: inb $0x64,%al # Get status 234 testb $0x2,%al # Busy? 235 jnz seta20.1 # Yes 236 movb $0xd1,%al # Command: Write 237 outb %al,$0x64 # output port 238seta20.2: inb $0x64,%al # Get status 239 testb $0x2,%al # Busy? 240 jnz seta20.2 # Yes 241 movb $0xdf,%al # Enable 242 outb %al,$0x60 # A20 243 sti # Enable interrupts 244 retw # To caller
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248 249/* 250 * BTX client to start btxldr 251 */ 252 .code32 253btx_client: movl $(MEM_ARG_BTX-MEM_BTX_CLIENT+MEM_ARG_SIZE-4), %esi
| 245 246/* 247 * BTX client to start btxldr 248 */ 249 .code32 250btx_client: movl $(MEM_ARG_BTX-MEM_BTX_CLIENT+MEM_ARG_SIZE-4), %esi
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254 // %ds:(%esi) -> end 255 // of boot[12] args 256 movl $(MEM_ARG_SIZE/4), %ecx // Number of words to push 257 std // Go backwards 258push_arg: lodsl // Read argument 259 pushl %eax // Push it onto the stack 260 loop push_arg // Push all of the arguments 261 cld // In case anyone depends 262 // on this 263 pushl MEM_ARG_BTX-MEM_BTX_CLIENT+MEM_ARG_SIZE // Entry point of 264 // the loader 265 pushl %eax // Emulate a near call 266 movl $0x1, %eax // 'exec' system call 267 int $INT_SYS // BTX system call
| 251 # %ds:(%esi) -> end 252 # of boot[12] args 253 movl $(MEM_ARG_SIZE/4), %ecx # Number of words to push 254 std # Go backwards 255push_arg: lodsl # Read argument 256 pushl %eax # Push it onto the stack 257 loop push_arg # Push all of the arguments 258 cld # In case anyone depends on this 259 pushl MEM_ARG_BTX-MEM_BTX_CLIENT+MEM_ARG_SIZE # Entry point of 260 # the loader 261 pushl %eax # Emulate a near call 262 movl $0x1, %eax # 'exec' system call 263 int $INT_SYS # BTX system call
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268btx_client_end: 269 .code16 270 271 .p2align 4 272/* 273 * Global descriptor table. 274 */
| 264btx_client_end: 265 .code16 266 267 .p2align 4 268/* 269 * Global descriptor table. 270 */
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275gdt: .word 0x0,0x0,0x0,0x0 // Null entry 276 .word 0xffff,0x0,0x9200,0xcf // SEL_SDATA 277 .word 0xffff,0x0,0x9200,0x0 // SEL_RDATA 278 .word 0xffff,0x0,0x9a00,0xcf // SEL_SCODE (32-bit) 279 .word 0xffff,0x0,0x9a00,0x8f // SEL_SCODE16 (16-bit)
| 271gdt: .word 0x0,0x0,0x0,0x0 # Null entry 272 .word 0xffff,0x0,0x9200,0xcf # SEL_SDATA 273 .word 0xffff,0x0,0x9200,0x0 # SEL_RDATA 274 .word 0xffff,0x0,0x9a00,0xcf # SEL_SCODE (32-bit) 275 .word 0xffff,0x0,0x9a00,0x8f # SEL_SCODE16 (16-bit)
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280gdt.1: 281/* 282 * Pseudo-descriptors. 283 */
| 276gdt.1: 277/* 278 * Pseudo-descriptors. 279 */
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284gdtdesc: .word gdt.1-gdt-1 // Limit 285 .long gdt // Base
| 280gdtdesc: .word gdt.1-gdt-1 # Limit 281 .long gdt # Base
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286 287welcome_msg: .asciz "PXE Loader 1.00\r\n\n" 288bootinfo_msg: .asciz "Building the boot loader arguments\r\n" 289relocate_msg: .asciz "Relocating the loader and the BTX\r\n" 290jump_message: .asciz "Starting the BTX loader\r\n" 291 292 .p2align 4 293end:
| 282 283welcome_msg: .asciz "PXE Loader 1.00\r\n\n" 284bootinfo_msg: .asciz "Building the boot loader arguments\r\n" 285relocate_msg: .asciz "Relocating the loader and the BTX\r\n" 286jump_message: .asciz "Starting the BTX loader\r\n" 287 288 .p2align 4 289end:
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