diff options
Diffstat (limited to 'src/arch/i386/prefix/dskprefix.S')
| -rw-r--r-- | src/arch/i386/prefix/dskprefix.S | 383 |
1 files changed, 0 insertions, 383 deletions
diff --git a/src/arch/i386/prefix/dskprefix.S b/src/arch/i386/prefix/dskprefix.S deleted file mode 100644 index 7aa017ccd..000000000 --- a/src/arch/i386/prefix/dskprefix.S +++ /dev/null @@ -1,383 +0,0 @@ -/* NOTE: this boot sector contains instructions that need at least an 80186. - * Yes, as86 has a bug somewhere in the valid instruction set checks. - * - */ - -/* floppyload.S Copyright (C) 1991, 1992 Linus Torvalds - * modified by Drew Eckhardt - * modified by Bruce Evans (bde) - * - * floppyprefix.S is loaded at 0x0000:0x7c00 by the bios-startup routines. - * - * It then loads the system at SYSSEG<<4, using BIOS interrupts. - * - * The loader has been made as simple as possible, and continuous read errors - * will result in a unbreakable loop. Reboot by hand. It loads pretty fast by - * getting whole tracks at a time whenever possible. - */ - -FILE_LICENCE ( GPL2_ONLY ) - -.equ BOOTSEG, 0x07C0 /* original address of boot-sector */ - -.equ SYSSEG, 0x1000 /* system loaded at SYSSEG<<4 */ - - .org 0 - .arch i386 - .text - .section ".prefix", "ax", @progbits - .code16 - .globl _dsk_start -_dsk_start: - - jmp $BOOTSEG, $go /* reload cs:ip to match relocation addr */ -go: - movw $0x2000-12, %di /* 0x2000 is arbitrary value >= length */ - /* of bootsect + room for stack + 12 for */ - /* saved disk parm block */ - - movw $BOOTSEG, %ax - movw %ax,%ds - movw %ax,%es - movw %ax,%ss /* put stack at BOOTSEG:0x4000-12. */ - movw %di,%sp - -/* Many BIOS's default disk parameter tables will not recognize multi-sector - * reads beyond the maximum sector number specified in the default diskette - * parameter tables - this may mean 7 sectors in some cases. - * - * Since single sector reads are slow and out of the question, we must take care - * of this by creating new parameter tables (for the first disk) in RAM. We - * will set the maximum sector count to 36 - the most we will encounter on an - * ED 2.88. High doesn't hurt. Low does. - * - * Segments are as follows: ds=es=ss=cs - BOOTSEG - */ - - xorw %cx,%cx - movw %cx,%es /* access segment 0 */ - movw $0x78, %bx /* 0:bx is parameter table address */ - pushw %ds /* save ds */ -/* 0:bx is parameter table address */ - ldsw %es:(%bx),%si /* loads ds and si */ - - movw %ax,%es /* ax is BOOTSECT (loaded above) */ - movb $6, %cl /* copy 12 bytes */ - cld - pushw %di /* keep a copy for later */ - rep - movsw /* ds:si is source, es:di is dest */ - popw %di - - movb $36,%es:4(%di) - - movw %cx,%ds /* access segment 0 */ - xchgw %di,(%bx) - movw %es,%si - xchgw %si,2(%bx) - popw %ds /* restore ds */ - movw %di, dpoff /* save old parameters */ - movw %si, dpseg /* to restore just before finishing */ - pushw %ds - popw %es /* reload es */ - -/* Note that es is already set up. Also cx is 0 from rep movsw above. */ - - xorb %ah,%ah /* reset FDC */ - xorb %dl,%dl - int $0x13 - -/* Get disk drive parameters, specifically number of sectors/track. - * - * It seems that there is no BIOS call to get the number of sectors. Guess - * 36 sectors if sector 36 can be read, 18 sectors if sector 18 can be read, - * 15 if sector 15 can be read. Otherwise guess 9. - */ - - movw $disksizes, %si /* table of sizes to try */ - -probe_loop: - lodsb - cbtw /* extend to word */ - movw %ax, sectors - cmpw $disksizes+4, %si - jae got_sectors /* if all else fails, try 9 */ - xchgw %cx,%ax /* cx = track and sector */ - xorw %dx,%dx /* drive 0, head 0 */ - movw $0x0200, %bx /* address after boot sector */ - /* (512 bytes from origin, es = cs) */ - movw $0x0201, %ax /* service 2, 1 sector */ - int $0x13 - jc probe_loop /* try next value */ - -got_sectors: - movw $msg1end-msg1, %cx - movw $msg1, %si - call print_str - -/* ok, we've written the Loading... message, now we want to load the system */ - - movw $SYSSEG, %ax - movw %ax,%es /* segment of SYSSEG<<4 */ - pushw %es - call read_it - -/* This turns off the floppy drive motor, so that we enter the kernel in a - * known state, and don't have to worry about it later. - */ - movw $0x3f2, %dx - xorb %al,%al - outb %al,%dx - - call print_nl - pop %es /* = SYSSEG */ - -/* Restore original disk parameters */ - movw $0x78, %bx - movw dpoff, %di - movw dpseg, %si - xorw %ax,%ax - movw %ax,%ds - movw %di,(%bx) - movw %si,2(%bx) - - /* Everything now loaded. %es = SYSSEG, so %es:0000 points to - * start of loaded image. - */ - - /* Jump to loaded copy */ - ljmp $SYSSEG, $start_runtime - -endseg: .word SYSSEG - .section ".zinfo.fixup", "a", @progbits /* Compressor fixups */ - .ascii "ADDW" - .long endseg - .long 16 - .long 0 - .previous - -/* This routine loads the system at address SYSSEG<<4, making sure no 64kB - * boundaries are crossed. We try to load it as fast as possible, loading whole - * tracks whenever we can. - * - * in: es - starting address segment (normally SYSSEG) - */ -read_it: - movw $0,sread /* load whole image including prefix */ - movw %es,%ax - testw $0x0fff, %ax -die: jne die /* es must be at 64kB boundary */ - xorw %bx,%bx /* bx is starting address within segment */ -rp_read: - movw %es,%ax - movw %bx,%dx - movb $4, %cl - shrw %cl,%dx /* bx is always divisible by 16 */ - addw %dx,%ax - cmpw endseg, %ax /* have we loaded all yet? */ - jb ok1_read - ret -ok1_read: - movw sectors, %ax - subw sread, %ax - movw %ax,%cx - shlw $9, %cx - addw %bx,%cx - jnc ok2_read - je ok2_read - xorw %ax,%ax - subw %bx,%ax - shrw $9, %ax -ok2_read: - call read_track - movw %ax,%cx - addw sread, %ax - cmpw sectors, %ax - jne ok3_read - movw $1, %ax - subw head, %ax - jne ok4_read - incw track -ok4_read: - movw %ax, head - xorw %ax,%ax -ok3_read: - movw %ax, sread - shlw $9, %cx - addw %cx,%bx - jnc rp_read - movw %es,%ax - addb $0x10, %ah - movw %ax,%es - xorw %bx,%bx - jmp rp_read - -read_track: - pusha - pushw %ax - pushw %bx - pushw %bp /* just in case the BIOS is buggy */ - movw $0x0e2e, %ax /* 0x2e = . */ - movw $0x0007, %bx - int $0x10 - popw %bp - popw %bx - popw %ax - - movw track, %dx - movw sread, %cx - incw %cx - movb %dl,%ch - movw head, %dx - movb %dl,%dh - andw $0x0100, %dx - movb $2, %ah - - pushw %dx /* save for error dump */ - pushw %cx - pushw %bx - pushw %ax - - int $0x13 - jc bad_rt - addw $8, %sp - popa - ret - -bad_rt: pushw %ax /* save error code */ - call print_all /* ah = error, al = read */ - - xorb %ah,%ah - xorb %dl,%dl - int $0x13 - - addw $10, %sp - popa - jmp read_track - -/* print_all is for debugging purposes. It will print out all of the registers. - * The assumption is that this is called from a routine, with a stack frame like - * dx - * cx - * bx - * ax - * error - * ret <- sp - */ - -print_all: - call print_nl /* nl for readability */ - movw $5, %cx /* error code + 4 registers */ - movw %sp,%bp - -print_loop: - pushw %cx /* save count left */ - - cmpb $5, %cl - jae no_reg /* see if register name is needed */ - - movw $0x0007, %bx /* page 0, attribute 7 (normal) */ - movw $0xe05+0x41-1, %ax - subb %cl,%al - int $0x10 - - movb $0x58, %al /* 'X' */ - int $0x10 - - movb $0x3A, %al /* ':' */ - int $0x10 - -no_reg: - addw $2, %bp /* next register */ - call print_hex /* print it */ - movb $0x20, %al /* print a space */ - int $0x10 - popw %cx - loop print_loop - call print_nl /* nl for readability */ - ret - -print_str: - movw $0x0007, %bx /* page 0, attribute 7 (normal) */ - movb $0x0e, %ah /* write char, tty mode */ -prloop: - lodsb - int $0x10 - loop prloop - ret - -print_nl: - movw $0x0007, %bx /* page 0, attribute 7 (normal) */ - movw $0xe0d, %ax /* CR */ - int $0x10 - movb $0xa, %al /* LF */ - int $0x10 - ret - -/* print_hex prints the word pointed to by ss:bp in hexadecimal. */ - -print_hex: - movw (%bp),%dx /* load word into dx */ - movb $4, %cl - movb $0x0e, %ah /* write char, tty mode */ - movw $0x0007, %bx /* page 0, attribute 7 (normal) */ - call print_digit - call print_digit - call print_digit -/* fall through */ -print_digit: - rol %cl,%dx /* rotate so that lowest 4 bits are used */ - movb $0x0f, %al /* mask for nybble */ - andb %dl,%al - addb $0x90, %al /* convert al to ascii hex (four instructions) */ - daa - adcb $0x40, %al - daa - int $0x10 - ret - -sread: .word 0 /* sectors read of current track */ -head: .word 0 /* current head */ -track: .word 0 /* current track */ - -sectors: - .word 0 - -dpseg: .word 0 -dpoff: .word 0 - -disksizes: - .byte 36,18,15,9 - -msg1: - .ascii "Loading ROM image" -msg1end: - - .org 510, 0 - .word 0xAA55 - -start_runtime: - /* Install iPXE */ - call install - - /* Set up real-mode stack */ - movw %bx, %ss - movw $_estack16, %sp - - /* Jump to .text16 segment */ - pushw %ax - pushw $1f - lret - .section ".text16", "awx", @progbits -1: - pushl $main - pushw %cs - call prot_call - popl %ecx /* discard */ - - /* Uninstall iPXE */ - call uninstall - - /* Boot next device */ - int $0x18 - |