| boot0.S (185562) | boot0.S (185579) |
|---|---|
| 1/* 2 * Copyright (c) 2008 Luigi Rizzo (mostly documentation) 3 * Copyright (c) 2002 Bruce M. Simpson 4 * Copyright (c) 1998 Robert Nordier 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms are freely 8 * permitted provided that the above copyright notice and this 9 * paragraph and the following disclaimer are duplicated in all 10 * such forms. 11 * 12 * This software is provided "AS IS" and without any express or 13 * implied warranties, including, without limitation, the implied 14 * warranties of merchantability and fitness for a particular 15 * purpose. 16 * | 1/* 2 * Copyright (c) 2008 Luigi Rizzo (mostly documentation) 3 * Copyright (c) 2002 Bruce M. Simpson 4 * Copyright (c) 1998 Robert Nordier 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms are freely 8 * permitted provided that the above copyright notice and this 9 * paragraph and the following disclaimer are duplicated in all 10 * such forms. 11 * 12 * This software is provided "AS IS" and without any express or 13 * implied warranties, including, without limitation, the implied 14 * warranties of merchantability and fitness for a particular 15 * purpose. 16 * |
| 17 * $FreeBSD: head/sys/boot/i386/boot0/boot0.S 185562 2008-12-02 14:57:48Z luigi $ | 17 * $FreeBSD: head/sys/boot/i386/boot0/boot0.S 185579 2008-12-03 14:53:59Z luigi $ |
| 18 */ 19 20/* build options: */ 21#ifdef SIO /* use serial console on COM1. */ 22#endif 23 24#ifdef PXE /* enable PXE/INT18 booting with F6 */ 25#endif 26 27#ifdef CHECK_DRIVE /* make sure we boot from a HD. */ 28#endif 29 30#ifdef ONLY_F_KEYS /* Only F1..F6, no digits on console */ 31#endif 32 | 18 */ 19 20/* build options: */ 21#ifdef SIO /* use serial console on COM1. */ 22#endif 23 24#ifdef PXE /* enable PXE/INT18 booting with F6 */ 25#endif 26 27#ifdef CHECK_DRIVE /* make sure we boot from a HD. */ 28#endif 29 30#ifdef ONLY_F_KEYS /* Only F1..F6, no digits on console */ 31#endif 32 |
| 33#ifdef VOLUME_SERIAL /* support Volume serial number */ 34#define B0_BASE 0x1ae /* move the internal data area */ 35#define SAVE_MEMORY 36#else 37#define B0_BASE 0x1b2 38#endif 39 |
|
| 33#ifdef TEST /* enable some test code */ | 40#ifdef TEST /* enable some test code */ |
| 34#ifndef ONLY_F_KEYS 35#define ONLY_F_KEYS /* make room for the test code */ | 41#define SAVE_MEMORY 42#define SAVE_MORE_MEMORY |
| 36#endif | 43#endif |
| 37#endif | |
| 38 39/* 40 * Note - this code uses many tricks to save space and fit in one sector. 41 * This includes using side effects of certain instructions, reusing 42 * register values from previous operations, etc. 43 * Be extremely careful when changing the code, even for simple things. 44 */ 45 --- 67 unchanged lines hidden (view full) --- 113 * 114 * NHRDRV is the address in segment 0 where the BIOS writes the 115 * total number of hard disks in the system. 116 * LOAD is the original load address and cannot be changed. 117 * ORIGIN is the relocation address. If you change it, you also need 118 * to change the value passed to the linker in the Makefile 119 * PRT_OFF is the location of the partition table (from the MBR standard). 120 * B0_OFF is the location of the data area, known to boot0cfg so | 44 45/* 46 * Note - this code uses many tricks to save space and fit in one sector. 47 * This includes using side effects of certain instructions, reusing 48 * register values from previous operations, etc. 49 * Be extremely careful when changing the code, even for simple things. 50 */ 51 --- 67 unchanged lines hidden (view full) --- 119 * 120 * NHRDRV is the address in segment 0 where the BIOS writes the 121 * total number of hard disks in the system. 122 * LOAD is the original load address and cannot be changed. 123 * ORIGIN is the relocation address. If you change it, you also need 124 * to change the value passed to the linker in the Makefile 125 * PRT_OFF is the location of the partition table (from the MBR standard). 126 * B0_OFF is the location of the data area, known to boot0cfg so |
| 121 * it cannot be changed. | 127 * it cannot be changed. Computed as a negative offset from 0x200 |
| 122 * MAGIC is the signature of a boot block. 123 */ 124 125 .set NHRDRV,0x475 # Number of hard drives 126 .set ORIGIN,0x600 # Execution address 127 .set LOAD,0x7c00 # Load address 128 129 .set PRT_OFF,0x1be # Partition table | 128 * MAGIC is the signature of a boot block. 129 */ 130 131 .set NHRDRV,0x475 # Number of hard drives 132 .set ORIGIN,0x600 # Execution address 133 .set LOAD,0x7c00 # Load address 134 135 .set PRT_OFF,0x1be # Partition table |
| 130 .set B0_OFF,0x1b2 # Offset of boot0 data | 136 .set B0_OFF,(B0_BASE-0x200) # Offset of boot0 data |
| 131 132 .set MAGIC,0xaa55 # Magic: bootable 133 134 .set KEY_ENTER,0x1c # Enter key scan code 135 .set KEY_F1,0x3b # F1 key scan code 136 .set KEY_1,0x02 # #1 key scan code 137 138 .set ASCII_BEL,'#' # ASCII code for <BEL> 139 .set ASCII_CR,0x0D # ASCII code for <CR> 140 141/* 142 * Offsets of variables in the block at B0_OFF, and in the volatile 143 * data area, computed as displacement from %bp. 144 * We need to define them as constant as the assembler cannot 145 * compute them in its single pass. 146 */ | 137 138 .set MAGIC,0xaa55 # Magic: bootable 139 140 .set KEY_ENTER,0x1c # Enter key scan code 141 .set KEY_F1,0x3b # F1 key scan code 142 .set KEY_1,0x02 # #1 key scan code 143 144 .set ASCII_BEL,'#' # ASCII code for <BEL> 145 .set ASCII_CR,0x0D # ASCII code for <CR> 146 147/* 148 * Offsets of variables in the block at B0_OFF, and in the volatile 149 * data area, computed as displacement from %bp. 150 * We need to define them as constant as the assembler cannot 151 * compute them in its single pass. 152 */ |
| 147 .set _NXTDRV, -0x48 # Next drive 148 .set _OPT, -0x47 # Default option 149 .set _SETDRV, -0x46 # Drive to force 150 .set _FLAGS, -0x45 # Flags | 153 .set _NXTDRV, B0_OFF+6 # Next drive 154 .set _OPT, B0_OFF+7 # Default option 155 .set _SETDRV, B0_OFF+8 # Drive to force 156 .set _FLAGS, B0_OFF+9 # Flags |
| 151 .set SETDRV, 0x20 # the 'setdrv' flag 152 .set NOUPDATE, 0x40 # the 'noupdate' flag 153 .set USEPACKET, 0x80 # the 'packet' flag | 157 .set SETDRV, 0x20 # the 'setdrv' flag 158 .set NOUPDATE, 0x40 # the 'noupdate' flag 159 .set USEPACKET, 0x80 # the 'packet' flag |
| 154 .set _TICKS, -0x44 # Timeout ticks 155 .set _FAKE,0x0 # Fake partition table | 160 161 /* ticks is at a fixed position */ 162 .set _TICKS, (PRT_OFF - 0x200 - 2) # Timeout ticks |
| 156 .set _MNUOPT, 0x10 # Saved menu entries 157 158 .set TLEN, (desc_ofs - bootable_ids) # size of bootable ids 159 .globl start # Entry point 160 .code16 # This runs in real mode 161 162/* 163 * MAIN ENTRY POINT --- 91 unchanged lines hidden (view full) --- 255 256 /* 257 * Loop around on the partition table, printing values until we 258 * pass a 256 byte boundary. 259 */ 260read_entry: movb %ch,-0x4(%bx) # Zero active flag (ch == 0) 261 btw %dx,_FLAGS(%bp) # Entry enabled? 262 jnc next_entry # No | 163 .set _MNUOPT, 0x10 # Saved menu entries 164 165 .set TLEN, (desc_ofs - bootable_ids) # size of bootable ids 166 .globl start # Entry point 167 .code16 # This runs in real mode 168 169/* 170 * MAIN ENTRY POINT --- 91 unchanged lines hidden (view full) --- 262 263 /* 264 * Loop around on the partition table, printing values until we 265 * pass a 256 byte boundary. 266 */ 267read_entry: movb %ch,-0x4(%bx) # Zero active flag (ch == 0) 268 btw %dx,_FLAGS(%bp) # Entry enabled? 269 jnc next_entry # No |
| 263 /* 264 * Lookup type in the 'non_bootable_ids' table, skip matching entries. 265 * This is implemented is by setting %di to the start of the 266 * exclude table, and %cl to the length of the table itself. After the 267 * 'repne scasb' the zero flag is set if we found a match. 268 * If not, %di points to the beginning of the 'valid' types, 269 * which is what we need for the next check. 270 */ | |
| 271 movb (%bx),%al # Load type | 270 movb (%bx),%al # Load type |
| 272 movw $non_bootable_ids,%di # Lookup tables 273 movb $(bootable_ids-non_bootable_ids),%cl # length 274 repne # Exclude 275 scasb # partition? 276 je next_entry # Yes, ignore it | 271 test %al, %al # skip empty partition 272 jz next_entry |
| 277 /* | 273 /* |
| 278 * Now scan the table of bootable ids, which starts at %di and has | 274 * Scan the table of bootable ids, which starts at %di and has |
| 279 * length TLEN. On a match, %di points to the element following the 280 * match; the corresponding offset to the description is $(TLEN-1) 281 * bytes ahead. If we don't find a match, we hit the 'unknown' entry. 282 */ | 275 * length TLEN. On a match, %di points to the element following the 276 * match; the corresponding offset to the description is $(TLEN-1) 277 * bytes ahead. If we don't find a match, we hit the 'unknown' entry. 278 */ |
| 279 movw $bootable_ids,%di # Lookup tables |
|
| 283 movb $(TLEN),%cl # Number of entries 284 repne # Locate 285 scasb # type 286 /* 287 * Get the matching element in the next array. 288 * The byte at $(TLEN-1)(%di) contains the offset of the description 289 * string from %di, so we add the number and print the string. 290 */ --- 204 unchanged lines hidden (view full) --- 495 jmp *%bx # Invoke bootstrap 496 497/* 498 * Display routines 499 * putkey prints the option selected in %dl (F1..F5 or 1..5) followed by 500 * the string at %si 501 * putx: print the option in %dl followed by the string at %di 502 * also record the drive as valid. | 280 movb $(TLEN),%cl # Number of entries 281 repne # Locate 282 scasb # type 283 /* 284 * Get the matching element in the next array. 285 * The byte at $(TLEN-1)(%di) contains the offset of the description 286 * string from %di, so we add the number and print the string. 287 */ --- 204 unchanged lines hidden (view full) --- 492 jmp *%bx # Invoke bootstrap 493 494/* 495 * Display routines 496 * putkey prints the option selected in %dl (F1..F5 or 1..5) followed by 497 * the string at %si 498 * putx: print the option in %dl followed by the string at %di 499 * also record the drive as valid. |
| 503 * puts: print the string at %si followed by a crlf | |
| 504 * putn: print a crlf 505 * putstr: print the string at %si 506 * putchr: print the char in al 507 */ | 500 * putn: print a crlf 501 * putstr: print the string at %si 502 * putchr: print the char in al 503 */ |
| 508putkey: 509#ifndef SIO 510 movb $'F',%al # Display 511 callw putchr # 'F' 512#endif 513 movb $'1',%al # Prepare 514 addb %dl,%al # digit 515 jmp putstr.1 # Display the rest | |
| 516 517/* 518 * Display the option and record the drive as valid in the options. 519 * That last point is done using the btsw instruction which does 520 * a test and set. We don't care for the test part. 521 */ 522putx: btsw %dx,_MNUOPT(%bp) # Enable menu option 523 movw $item,%si # Display 524 callw putkey # key 525 movw %di,%si # Display the rest | 504 505/* 506 * Display the option and record the drive as valid in the options. 507 * That last point is done using the btsw instruction which does 508 * a test and set. We don't care for the test part. 509 */ 510putx: btsw %dx,_MNUOPT(%bp) # Enable menu option 511 movw $item,%si # Display 512 callw putkey # key 513 movw %di,%si # Display the rest |
| 514 callw putstr # Display string |
|
| 526 | 515 |
| 527puts: callw putstr # Display string 528 | |
| 529putn: movw $crlf,%si # To next line | 516putn: movw $crlf,%si # To next line |
| 517 jmp putstr |
|
| 530 | 518 |
| 519putkey: 520#ifndef SIO 521 movb $'F',%al # Display 522 callw putchr # 'F' 523#endif 524 movb $'1',%al # Prepare 525 addb %dl,%al # digit 526 527putstr.1: callw putchr # Display char |
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| 531putstr: lodsb # Get byte 532 testb $0x80,%al # End of string? | 528putstr: lodsb # Get byte 529 testb $0x80,%al # End of string? |
| 533 jnz putstr.2 # Yes 534putstr.1: callw putchr # Display char 535 jmp putstr # Continue 536putstr.2: andb $~0x80,%al # Clear MSB | 530 jz putstr.1 # No 531 andb $~0x80,%al # Clear MSB then print last |
| 537 538putchr: 539#ifndef SIO 540 pushw %bx # Save 541 movw $0x7,%bx # Page:attribute 542 movb $0xe,%ah # BIOS: Display 543 int $0x10 # character 544 popw %bx # Restore --- 51 unchanged lines hidden (view full) --- 596#else 597prompt: .ascii "\nDefault:" 598item: .ascii " "; .byte ' '|0x80 599#endif 600crlf: .ascii "\r"; .byte '\n'|0x80 601 602/* Partition type tables */ 603 | 532 533putchr: 534#ifndef SIO 535 pushw %bx # Save 536 movw $0x7,%bx # Page:attribute 537 movb $0xe,%ah # BIOS: Display 538 int $0x10 # character 539 popw %bx # Restore --- 51 unchanged lines hidden (view full) --- 591#else 592prompt: .ascii "\nDefault:" 593item: .ascii " "; .byte ' '|0x80 594#endif 595crlf: .ascii "\r"; .byte '\n'|0x80 596 597/* Partition type tables */ 598 |
| 604non_bootable_ids: 605 /* 606 * These entries identify invalid or NON BOOT types and partitions. 607 * 0: empty, 5: DOS3 ext. partition, 0xf: WIN95 ext partition 608 */ 609 .byte 0x0, 0x5, 0xf | |
| 610bootable_ids: 611 /* | 599bootable_ids: 600 /* |
| 612 * These values indicate bootable types we know the names of. 613 * 1: FAT12, 4: FAT16 <32M, 6: FAT16 > 32M, 7: NTFS 614 * 0xb: FAT32, 0xc: FAT32-LBA, 0xe: FAT16-LBA, 615 * 0x83: linux, 0xa5: FreeBSD, 0xa6: netbsd, 0xa9:openbsd | 601 * These values indicate bootable types we know about. 602 * Corresponding descriptions are at desc_ofs: 603 * Entries don't need to be sorted. |
| 616 */ | 604 */ |
| 617 .byte 0x1, 0x6, 0x7, 0xb, 0xc, 0xe, 0x83 618 .byte 0xa5, 0xa6, 0xa9, 0x4 | 605 .byte 0x1, 0x6, 0x7, 0xb, 0xc 606#ifndef SAVE_MEMORY 607 .byte 0xe 608#endif 609 .byte 0x83, 0xa5, 0xa6, 0xa9, 0x4 610#ifndef SAVE_MORE_MEMORY 611 .byte 0x5, 0xf 612#endif 613 |
| 619desc_ofs: 620 /* 621 * Offsets that match the known types above, used to point to the 622 * actual partition name. The last entry must point to os_misc, 623 * which is used for non-matching names. 624 */ | 614desc_ofs: 615 /* 616 * Offsets that match the known types above, used to point to the 617 * actual partition name. The last entry must point to os_misc, 618 * which is used for non-matching names. 619 */ |
| 625 .byte os_dos-. # 1, DOS 626 .byte os_dos-. # 6, DOS/WIN 627 .byte os_win-. # 7, Windows 628 .byte os_win-. # 11, Windows 629 .byte os_win-. # 12, Windows 630 .byte os_win-. # 14, Windows | 620 .byte os_dos-. # 1, FAT12 DOS 621 .byte os_dos-. # 6, FAT16 <32M, DOS/WIN 622 .byte os_win-. # 7, FAT16 >=32M Windows 623 .byte os_win-. # 11, FAT32 624 .byte os_win-. # 12, FAT32-LBA 625#ifndef SAVE_MEMORY 626 .byte os_win-. # 14, FAT16-LBA 627#endif |
| 631 .byte os_linux-. # 131, Linux 632 .byte os_freebsd-. # 165, FreeBSD 633 .byte os_bsd-. # 166, OpenBSD 634 .byte os_bsd-. # 169, NetBSD | 628 .byte os_linux-. # 131, Linux 629 .byte os_freebsd-. # 165, FreeBSD 630 .byte os_bsd-. # 166, OpenBSD 631 .byte os_bsd-. # 169, NetBSD |
| 635 .byte os_dos-. # 4, DOS | 632 .byte os_dos-. # 4, FAT16 < 32M 633#ifndef SAVE_MORE_MEMORY 634 .byte os_ext-. # 5, DOS Ext 635 .byte os_ext-. # 15, DOS Ext-LBA 636#endif 637 |
| 636 .byte os_misc-. # Unknown 637 638 /* 639 * And here are the strings themselves. The last byte of 640 * the string has bit 7 set. 641 */ 642os_misc: .byte '?'|0x80 643os_dos: | 638 .byte os_misc-. # Unknown 639 640 /* 641 * And here are the strings themselves. The last byte of 642 * the string has bit 7 set. 643 */ 644os_misc: .byte '?'|0x80 645os_dos: |
| 644#if !defined(TEST) /* DOS string only if room */ | 646#ifndef SAVE_MEMORY /* DOS string only if room */ |
| 645 .ascii "DO"; .byte 'S'|0x80 646#endif 647os_win: .ascii "WI"; .byte 'N'|0x80 648os_linux: .ascii "Linu"; .byte 'x'|0x80 649os_freebsd: .ascii "Free" 650os_bsd: .ascii "BS"; .byte 'D'|0x80 | 647 .ascii "DO"; .byte 'S'|0x80 648#endif 649os_win: .ascii "WI"; .byte 'N'|0x80 650os_linux: .ascii "Linu"; .byte 'x'|0x80 651os_freebsd: .ascii "Free" 652os_bsd: .ascii "BS"; .byte 'D'|0x80 |
| 653#ifndef SAVE_MORE_MEMORY 654os_ext: .ascii "EX"; .byte 'T'|0x80 655#endif |
|
| 651 | 656 |
| 652 .org B0_OFF,0x90 | 657 .org (0x200 + B0_OFF),0x90 |
| 653/* 654 * The boot0 version 1.0 parameter table. 655 * Do not move it nor change the "Drive " string, boot0cfg 656 * uses its offset and content to identify the boot sector. 657 * The other fields are sometimes changed before writing back to the drive 658 * Be especially careful that nxtdrv: must come after drive:, as it 659 * is part of the same string. 660 */ 661drive: .ascii "Drive " 662nxtdrv: .byte 0x0 # Next drive number 663opt: .byte 0x0 # Option 664setdrv_num: .byte 0x80 # Drive to force 665flags: .byte FLAGS # Flags | 658/* 659 * The boot0 version 1.0 parameter table. 660 * Do not move it nor change the "Drive " string, boot0cfg 661 * uses its offset and content to identify the boot sector. 662 * The other fields are sometimes changed before writing back to the drive 663 * Be especially careful that nxtdrv: must come after drive:, as it 664 * is part of the same string. 665 */ 666drive: .ascii "Drive " 667nxtdrv: .byte 0x0 # Next drive number 668opt: .byte 0x0 # Option 669setdrv_num: .byte 0x80 # Drive to force 670flags: .byte FLAGS # Flags |
| 671#ifdef VOLUME_SERIAL 672 .byte 0xa8,0xa8,0xa8,0xa8 # Volume Serial Number 673#endif |
|
| 666ticks: .word TICKS # Delay 667 668 .org PRT_OFF 669/* 670 * Here is the 64 byte partition table that fdisk would fiddle with. 671 */ 672partbl: .fill 0x40,0x1,0x0 # Partition table 673 .word MAGIC # Magic number 674 .org 0x200 # again, safety check 675endblock: | 674ticks: .word TICKS # Delay 675 676 .org PRT_OFF 677/* 678 * Here is the 64 byte partition table that fdisk would fiddle with. 679 */ 680partbl: .fill 0x40,0x1,0x0 # Partition table 681 .word MAGIC # Magic number 682 .org 0x200 # again, safety check 683endblock: |