827 lines
21 KiB
ArmAsm
827 lines
21 KiB
ArmAsm
/*
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* setup.S Copyright (C) 1991, 1992 Linus Torvalds
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*
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* setup.s is responsible for getting the system data from the BIOS,
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* and putting them into the appropriate places in system memory.
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* both setup.s and system has been loaded by the bootblock.
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*
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* This code asks the bios for memory/disk/other parameters, and
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* puts them in a "safe" place: 0x90000-0x901FF, ie where the
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* boot-block used to be. It is then up to the protected mode
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* system to read them from there before the area is overwritten
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* for buffer-blocks.
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*
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* Move PS/2 aux init code to psaux.c
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* (troyer@saifr00.cfsat.Honeywell.COM) 03Oct92
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*
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* some changes and additional features by Christoph Niemann,
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* March 1993/June 1994 (Christoph.Niemann@linux.org)
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*
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* add APM BIOS checking by Stephen Rothwell, May 1994
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* (sfr@canb.auug.org.au)
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*
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* High load stuff, initrd support and position independency
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* by Hans Lermen & Werner Almesberger, February 1996
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* <lermen@elserv.ffm.fgan.de>, <almesber@lrc.epfl.ch>
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*
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* Video handling moved to video.S by Martin Mares, March 1996
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* <mj@k332.feld.cvut.cz>
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*
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* Extended memory detection scheme retwiddled by orc@pell.chi.il.us (david
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* parsons) to avoid loadlin confusion, July 1997
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*
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* Transcribed from Intel (as86) -> AT&T (gas) by Chris Noe, May 1999.
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* <stiker@northlink.com>
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*
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* Fix to work around buggy BIOSes which don't use carry bit correctly
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* and/or report extended memory in CX/DX for e801h memory size detection
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* call. As a result the kernel got wrong figures. The int15/e801h docs
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* from Ralf Brown interrupt list seem to indicate AX/BX should be used
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* anyway. So to avoid breaking many machines (presumably there was a reason
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* to orginally use CX/DX instead of AX/BX), we do a kludge to see
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* if CX/DX have been changed in the e801 call and if so use AX/BX .
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* Michael Miller, April 2001 <michaelm@mjmm.org>
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*
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* Added long mode checking and SSE force. March 2003, Andi Kleen.
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*/
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#include <asm/segment.h>
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#include <linux/utsrelease.h>
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#include <linux/compile.h>
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#include <asm/boot.h>
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#include <asm/e820.h>
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#include <asm/page.h>
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#include <asm/setup.h>
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/* Signature words to ensure LILO loaded us right */
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#define SIG1 0xAA55
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#define SIG2 0x5A5A
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INITSEG = DEF_INITSEG # 0x9000, we move boot here, out of the way
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SYSSEG = DEF_SYSSEG # 0x1000, system loaded at 0x10000 (65536).
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SETUPSEG = DEF_SETUPSEG # 0x9020, this is the current segment
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# ... and the former contents of CS
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DELTA_INITSEG = SETUPSEG - INITSEG # 0x0020
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.code16
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.globl begtext, begdata, begbss, endtext, enddata, endbss
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.text
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begtext:
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.data
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begdata:
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.bss
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begbss:
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.text
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start:
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jmp trampoline
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# This is the setup header, and it must start at %cs:2 (old 0x9020:2)
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.ascii "HdrS" # header signature
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.word 0x0206 # header version number (>= 0x0105)
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# or else old loadlin-1.5 will fail)
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realmode_swtch: .word 0, 0 # default_switch, SETUPSEG
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start_sys_seg: .word SYSSEG
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.word kernel_version # pointing to kernel version string
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# above section of header is compatible
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# with loadlin-1.5 (header v1.5). Don't
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# change it.
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type_of_loader: .byte 0 # = 0, old one (LILO, Loadlin,
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# Bootlin, SYSLX, bootsect...)
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# See Documentation/i386/boot.txt for
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# assigned ids
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# flags, unused bits must be zero (RFU) bit within loadflags
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loadflags:
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LOADED_HIGH = 1 # If set, the kernel is loaded high
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CAN_USE_HEAP = 0x80 # If set, the loader also has set
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# heap_end_ptr to tell how much
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# space behind setup.S can be used for
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# heap purposes.
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# Only the loader knows what is free
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#ifndef __BIG_KERNEL__
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.byte 0
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#else
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.byte LOADED_HIGH
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#endif
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setup_move_size: .word 0x8000 # size to move, when setup is not
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# loaded at 0x90000. We will move setup
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# to 0x90000 then just before jumping
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# into the kernel. However, only the
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# loader knows how much data behind
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# us also needs to be loaded.
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code32_start: # here loaders can put a different
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# start address for 32-bit code.
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#ifndef __BIG_KERNEL__
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.long 0x1000 # 0x1000 = default for zImage
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#else
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.long 0x100000 # 0x100000 = default for big kernel
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#endif
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ramdisk_image: .long 0 # address of loaded ramdisk image
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# Here the loader puts the 32-bit
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# address where it loaded the image.
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# This only will be read by the kernel.
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ramdisk_size: .long 0 # its size in bytes
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bootsect_kludge:
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.long 0 # obsolete
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heap_end_ptr: .word modelist+1024 # (Header version 0x0201 or later)
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# space from here (exclusive) down to
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# end of setup code can be used by setup
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# for local heap purposes.
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pad1: .word 0
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cmd_line_ptr: .long 0 # (Header version 0x0202 or later)
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# If nonzero, a 32-bit pointer
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# to the kernel command line.
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# The command line should be
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# located between the start of
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# setup and the end of low
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# memory (0xa0000), or it may
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# get overwritten before it
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# gets read. If this field is
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# used, there is no longer
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# anything magical about the
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# 0x90000 segment; the setup
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# can be located anywhere in
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# low memory 0x10000 or higher.
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ramdisk_max: .long 0xffffffff
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kernel_alignment: .long 0x200000 # physical addr alignment required for
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# protected mode relocatable kernel
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#ifdef CONFIG_RELOCATABLE
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relocatable_kernel: .byte 1
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#else
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relocatable_kernel: .byte 0
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#endif
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pad2: .byte 0
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pad3: .word 0
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cmdline_size: .long COMMAND_LINE_SIZE-1 #length of the command line,
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#added with boot protocol
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#version 2.06
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trampoline: call start_of_setup
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.align 16
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# The offset at this point is 0x240
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.space (0xeff-0x240+1) # E820 & EDD space (ending at 0xeff)
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# End of setup header #####################################################
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start_of_setup:
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# Bootlin depends on this being done early
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movw $0x01500, %ax
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movb $0x81, %dl
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int $0x13
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#ifdef SAFE_RESET_DISK_CONTROLLER
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# Reset the disk controller.
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movw $0x0000, %ax
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movb $0x80, %dl
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int $0x13
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#endif
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# Set %ds = %cs, we know that SETUPSEG = %cs at this point
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movw %cs, %ax # aka SETUPSEG
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movw %ax, %ds
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# Check signature at end of setup
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cmpw $SIG1, setup_sig1
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jne bad_sig
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cmpw $SIG2, setup_sig2
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jne bad_sig
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jmp good_sig1
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# Routine to print asciiz string at ds:si
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prtstr:
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lodsb
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andb %al, %al
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jz fin
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call prtchr
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jmp prtstr
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fin: ret
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# Space printing
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prtsp2: call prtspc # Print double space
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prtspc: movb $0x20, %al # Print single space (note: fall-thru)
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prtchr:
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pushw %ax
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pushw %cx
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movw $0007,%bx
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movw $0x01, %cx
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movb $0x0e, %ah
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int $0x10
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popw %cx
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popw %ax
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ret
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beep: movb $0x07, %al
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jmp prtchr
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no_sig_mess: .string "No setup signature found ..."
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good_sig1:
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jmp good_sig
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# We now have to find the rest of the setup code/data
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bad_sig:
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movw %cs, %ax # SETUPSEG
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subw $DELTA_INITSEG, %ax # INITSEG
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movw %ax, %ds
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xorb %bh, %bh
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movb (497), %bl # get setup sect from bootsect
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subw $4, %bx # LILO loads 4 sectors of setup
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shlw $8, %bx # convert to words (1sect=2^8 words)
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movw %bx, %cx
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shrw $3, %bx # convert to segment
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addw $SYSSEG, %bx
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movw %bx, %cs:start_sys_seg
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# Move rest of setup code/data to here
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movw $2048, %di # four sectors loaded by LILO
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subw %si, %si
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movw %cs, %ax # aka SETUPSEG
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movw %ax, %es
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movw $SYSSEG, %ax
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movw %ax, %ds
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rep
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movsw
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movw %cs, %ax # aka SETUPSEG
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movw %ax, %ds
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cmpw $SIG1, setup_sig1
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jne no_sig
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cmpw $SIG2, setup_sig2
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jne no_sig
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jmp good_sig
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no_sig:
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lea no_sig_mess, %si
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call prtstr
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no_sig_loop:
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jmp no_sig_loop
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good_sig:
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movw %cs, %ax # aka SETUPSEG
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subw $DELTA_INITSEG, %ax # aka INITSEG
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movw %ax, %ds
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# Check if an old loader tries to load a big-kernel
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testb $LOADED_HIGH, %cs:loadflags # Do we have a big kernel?
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jz loader_ok # No, no danger for old loaders.
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cmpb $0, %cs:type_of_loader # Do we have a loader that
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# can deal with us?
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jnz loader_ok # Yes, continue.
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pushw %cs # No, we have an old loader,
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popw %ds # die.
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lea loader_panic_mess, %si
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call prtstr
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jmp no_sig_loop
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loader_panic_mess: .string "Wrong loader, giving up..."
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loader_ok:
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/* check for long mode. */
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/* we have to do this before the VESA setup, otherwise the user
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can't see the error message. */
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pushw %ds
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movw %cs,%ax
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movw %ax,%ds
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call verify_cpu
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testl %eax,%eax
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jz sse_ok
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no_longmode:
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call beep
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lea long_mode_panic,%si
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call prtstr
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no_longmode_loop:
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jmp no_longmode_loop
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long_mode_panic:
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.string "Your CPU does not support long mode. Use a 32bit distribution."
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.byte 0
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#include "../kernel/verify_cpu.S"
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sse_ok:
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popw %ds
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# tell BIOS we want to go to long mode
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movl $0xec00,%eax # declare target operating mode
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movl $2,%ebx # long mode
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int $0x15
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# Get memory size (extended mem, kB)
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xorl %eax, %eax
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movl %eax, (0x1e0)
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#ifndef STANDARD_MEMORY_BIOS_CALL
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movb %al, (E820NR)
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# Try three different memory detection schemes. First, try
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# e820h, which lets us assemble a memory map, then try e801h,
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# which returns a 32-bit memory size, and finally 88h, which
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# returns 0-64m
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# method E820H:
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# the memory map from hell. e820h returns memory classified into
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# a whole bunch of different types, and allows memory holes and
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# everything. We scan through this memory map and build a list
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# of the first 32 memory areas, which we return at [E820MAP].
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# This is documented at http://www.acpi.info/, in the ACPI 2.0 specification.
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#define SMAP 0x534d4150
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meme820:
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xorl %ebx, %ebx # continuation counter
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movw $E820MAP, %di # point into the whitelist
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# so we can have the bios
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# directly write into it.
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jmpe820:
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movl $0x0000e820, %eax # e820, upper word zeroed
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movl $SMAP, %edx # ascii 'SMAP'
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movl $20, %ecx # size of the e820rec
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pushw %ds # data record.
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popw %es
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int $0x15 # make the call
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jc bail820 # fall to e801 if it fails
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cmpl $SMAP, %eax # check the return is `SMAP'
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jne bail820 # fall to e801 if it fails
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# cmpl $1, 16(%di) # is this usable memory?
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# jne again820
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# If this is usable memory, we save it by simply advancing %di by
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# sizeof(e820rec).
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#
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good820:
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movb (E820NR), %al # up to 128 entries
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cmpb $E820MAX, %al
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jae bail820
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incb (E820NR)
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movw %di, %ax
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addw $20, %ax
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movw %ax, %di
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again820:
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cmpl $0, %ebx # check to see if
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jne jmpe820 # %ebx is set to EOF
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bail820:
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# method E801H:
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# memory size is in 1k chunksizes, to avoid confusing loadlin.
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# we store the 0xe801 memory size in a completely different place,
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# because it will most likely be longer than 16 bits.
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# (use 1e0 because that's what Larry Augustine uses in his
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# alternative new memory detection scheme, and it's sensible
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# to write everything into the same place.)
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meme801:
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stc # fix to work around buggy
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xorw %cx,%cx # BIOSes which don't clear/set
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xorw %dx,%dx # carry on pass/error of
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# e801h memory size call
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# or merely pass cx,dx though
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# without changing them.
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movw $0xe801, %ax
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int $0x15
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jc mem88
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cmpw $0x0, %cx # Kludge to handle BIOSes
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jne e801usecxdx # which report their extended
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cmpw $0x0, %dx # memory in AX/BX rather than
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jne e801usecxdx # CX/DX. The spec I have read
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movw %ax, %cx # seems to indicate AX/BX
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movw %bx, %dx # are more reasonable anyway...
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e801usecxdx:
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andl $0xffff, %edx # clear sign extend
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shll $6, %edx # and go from 64k to 1k chunks
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movl %edx, (0x1e0) # store extended memory size
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andl $0xffff, %ecx # clear sign extend
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addl %ecx, (0x1e0) # and add lower memory into
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# total size.
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# Ye Olde Traditional Methode. Returns the memory size (up to 16mb or
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# 64mb, depending on the bios) in ax.
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mem88:
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#endif
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movb $0x88, %ah
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int $0x15
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movw %ax, (2)
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# Set the keyboard repeat rate to the max
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movw $0x0305, %ax
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xorw %bx, %bx
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int $0x16
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# Check for video adapter and its parameters and allow the
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# user to browse video modes.
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call video # NOTE: we need %ds pointing
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# to bootsector
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# Get hd0 data...
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xorw %ax, %ax
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movw %ax, %ds
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ldsw (4 * 0x41), %si
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movw %cs, %ax # aka SETUPSEG
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subw $DELTA_INITSEG, %ax # aka INITSEG
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pushw %ax
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movw %ax, %es
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movw $0x0080, %di
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movw $0x10, %cx
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pushw %cx
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cld
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rep
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movsb
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# Get hd1 data...
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xorw %ax, %ax
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movw %ax, %ds
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ldsw (4 * 0x46), %si
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popw %cx
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popw %es
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movw $0x0090, %di
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rep
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movsb
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# Check that there IS a hd1 :-)
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movw $0x01500, %ax
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movb $0x81, %dl
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int $0x13
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jc no_disk1
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cmpb $3, %ah
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je is_disk1
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no_disk1:
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movw %cs, %ax # aka SETUPSEG
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subw $DELTA_INITSEG, %ax # aka INITSEG
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movw %ax, %es
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movw $0x0090, %di
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movw $0x10, %cx
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xorw %ax, %ax
|
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cld
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rep
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stosb
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is_disk1:
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|
|
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# Check for PS/2 pointing device
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movw %cs, %ax # aka SETUPSEG
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subw $DELTA_INITSEG, %ax # aka INITSEG
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movw %ax, %ds
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movb $0, (0x1ff) # default is no pointing device
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int $0x11 # int 0x11: equipment list
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testb $0x04, %al # check if mouse installed
|
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jz no_psmouse
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|
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movb $0xAA, (0x1ff) # device present
|
|
no_psmouse:
|
|
|
|
#include "../../i386/boot/edd.S"
|
|
|
|
# Now we want to move to protected mode ...
|
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cmpw $0, %cs:realmode_swtch
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|
jz rmodeswtch_normal
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|
|
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lcall *%cs:realmode_swtch
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|
|
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jmp rmodeswtch_end
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|
|
|
rmodeswtch_normal:
|
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pushw %cs
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call default_switch
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|
|
|
rmodeswtch_end:
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|
# we get the code32 start address and modify the below 'jmpi'
|
|
# (loader may have changed it)
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|
movl %cs:code32_start, %eax
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movl %eax, %cs:code32
|
|
|
|
# Now we move the system to its rightful place ... but we check if we have a
|
|
# big-kernel. In that case we *must* not move it ...
|
|
testb $LOADED_HIGH, %cs:loadflags
|
|
jz do_move0 # .. then we have a normal low
|
|
# loaded zImage
|
|
# .. or else we have a high
|
|
# loaded bzImage
|
|
jmp end_move # ... and we skip moving
|
|
|
|
do_move0:
|
|
movw $0x100, %ax # start of destination segment
|
|
movw %cs, %bp # aka SETUPSEG
|
|
subw $DELTA_INITSEG, %bp # aka INITSEG
|
|
movw %cs:start_sys_seg, %bx # start of source segment
|
|
cld
|
|
do_move:
|
|
movw %ax, %es # destination segment
|
|
incb %ah # instead of add ax,#0x100
|
|
movw %bx, %ds # source segment
|
|
addw $0x100, %bx
|
|
subw %di, %di
|
|
subw %si, %si
|
|
movw $0x800, %cx
|
|
rep
|
|
movsw
|
|
cmpw %bp, %bx # assume start_sys_seg > 0x200,
|
|
# so we will perhaps read one
|
|
# page more than needed, but
|
|
# never overwrite INITSEG
|
|
# because destination is a
|
|
# minimum one page below source
|
|
jb do_move
|
|
|
|
end_move:
|
|
# then we load the segment descriptors
|
|
movw %cs, %ax # aka SETUPSEG
|
|
movw %ax, %ds
|
|
|
|
# Check whether we need to be downward compatible with version <=201
|
|
cmpl $0, cmd_line_ptr
|
|
jne end_move_self # loader uses version >=202 features
|
|
cmpb $0x20, type_of_loader
|
|
je end_move_self # bootsect loader, we know of it
|
|
|
|
# Boot loader doesnt support boot protocol version 2.02.
|
|
# If we have our code not at 0x90000, we need to move it there now.
|
|
# We also then need to move the params behind it (commandline)
|
|
# Because we would overwrite the code on the current IP, we move
|
|
# it in two steps, jumping high after the first one.
|
|
movw %cs, %ax
|
|
cmpw $SETUPSEG, %ax
|
|
je end_move_self
|
|
|
|
cli # make sure we really have
|
|
# interrupts disabled !
|
|
# because after this the stack
|
|
# should not be used
|
|
subw $DELTA_INITSEG, %ax # aka INITSEG
|
|
movw %ss, %dx
|
|
cmpw %ax, %dx
|
|
jb move_self_1
|
|
|
|
addw $INITSEG, %dx
|
|
subw %ax, %dx # this will go into %ss after
|
|
# the move
|
|
move_self_1:
|
|
movw %ax, %ds
|
|
movw $INITSEG, %ax # real INITSEG
|
|
movw %ax, %es
|
|
movw %cs:setup_move_size, %cx
|
|
std # we have to move up, so we use
|
|
# direction down because the
|
|
# areas may overlap
|
|
movw %cx, %di
|
|
decw %di
|
|
movw %di, %si
|
|
subw $move_self_here+0x200, %cx
|
|
rep
|
|
movsb
|
|
ljmp $SETUPSEG, $move_self_here
|
|
|
|
move_self_here:
|
|
movw $move_self_here+0x200, %cx
|
|
rep
|
|
movsb
|
|
movw $SETUPSEG, %ax
|
|
movw %ax, %ds
|
|
movw %dx, %ss
|
|
end_move_self: # now we are at the right place
|
|
lidt idt_48 # load idt with 0,0
|
|
xorl %eax, %eax # Compute gdt_base
|
|
movw %ds, %ax # (Convert %ds:gdt to a linear ptr)
|
|
shll $4, %eax
|
|
addl $gdt, %eax
|
|
movl %eax, (gdt_48+2)
|
|
lgdt gdt_48 # load gdt with whatever is
|
|
# appropriate
|
|
|
|
# that was painless, now we enable a20
|
|
call empty_8042
|
|
|
|
movb $0xD1, %al # command write
|
|
outb %al, $0x64
|
|
call empty_8042
|
|
|
|
movb $0xDF, %al # A20 on
|
|
outb %al, $0x60
|
|
call empty_8042
|
|
|
|
#
|
|
# You must preserve the other bits here. Otherwise embarrasing things
|
|
# like laptops powering off on boot happen. Corrected version by Kira
|
|
# Brown from Linux 2.2
|
|
#
|
|
inb $0x92, %al #
|
|
orb $02, %al # "fast A20" version
|
|
outb %al, $0x92 # some chips have only this
|
|
|
|
# wait until a20 really *is* enabled; it can take a fair amount of
|
|
# time on certain systems; Toshiba Tecras are known to have this
|
|
# problem. The memory location used here (0x200) is the int 0x80
|
|
# vector, which should be safe to use.
|
|
|
|
xorw %ax, %ax # segment 0x0000
|
|
movw %ax, %fs
|
|
decw %ax # segment 0xffff (HMA)
|
|
movw %ax, %gs
|
|
a20_wait:
|
|
incw %ax # unused memory location <0xfff0
|
|
movw %ax, %fs:(0x200) # we use the "int 0x80" vector
|
|
cmpw %gs:(0x210), %ax # and its corresponding HMA addr
|
|
je a20_wait # loop until no longer aliased
|
|
|
|
# make sure any possible coprocessor is properly reset..
|
|
xorw %ax, %ax
|
|
outb %al, $0xf0
|
|
call delay
|
|
|
|
outb %al, $0xf1
|
|
call delay
|
|
|
|
# well, that went ok, I hope. Now we mask all interrupts - the rest
|
|
# is done in init_IRQ().
|
|
movb $0xFF, %al # mask all interrupts for now
|
|
outb %al, $0xA1
|
|
call delay
|
|
|
|
movb $0xFB, %al # mask all irq's but irq2 which
|
|
outb %al, $0x21 # is cascaded
|
|
|
|
# Well, that certainly wasn't fun :-(. Hopefully it works, and we don't
|
|
# need no steenking BIOS anyway (except for the initial loading :-).
|
|
# The BIOS-routine wants lots of unnecessary data, and it's less
|
|
# "interesting" anyway. This is how REAL programmers do it.
|
|
#
|
|
# Well, now's the time to actually move into protected mode. To make
|
|
# things as simple as possible, we do no register set-up or anything,
|
|
# we let the gnu-compiled 32-bit programs do that. We just jump to
|
|
# absolute address 0x1000 (or the loader supplied one),
|
|
# in 32-bit protected mode.
|
|
#
|
|
# Note that the short jump isn't strictly needed, although there are
|
|
# reasons why it might be a good idea. It won't hurt in any case.
|
|
movw $1, %ax # protected mode (PE) bit
|
|
lmsw %ax # This is it!
|
|
jmp flush_instr
|
|
|
|
flush_instr:
|
|
xorw %bx, %bx # Flag to indicate a boot
|
|
xorl %esi, %esi # Pointer to real-mode code
|
|
movw %cs, %si
|
|
subw $DELTA_INITSEG, %si
|
|
shll $4, %esi # Convert to 32-bit pointer
|
|
# NOTE: For high loaded big kernels we need a
|
|
# jmpi 0x100000,__KERNEL_CS
|
|
#
|
|
# but we yet haven't reloaded the CS register, so the default size
|
|
# of the target offset still is 16 bit.
|
|
# However, using an operand prefix (0x66), the CPU will properly
|
|
# take our 48 bit far pointer. (INTeL 80386 Programmer's Reference
|
|
# Manual, Mixing 16-bit and 32-bit code, page 16-6)
|
|
|
|
.byte 0x66, 0xea # prefix + jmpi-opcode
|
|
code32: .long 0x1000 # will be set to 0x100000
|
|
# for big kernels
|
|
.word __KERNEL_CS
|
|
|
|
# Here's a bunch of information about your current kernel..
|
|
kernel_version: .ascii UTS_RELEASE
|
|
.ascii " ("
|
|
.ascii LINUX_COMPILE_BY
|
|
.ascii "@"
|
|
.ascii LINUX_COMPILE_HOST
|
|
.ascii ") "
|
|
.ascii UTS_VERSION
|
|
.byte 0
|
|
|
|
# This is the default real mode switch routine.
|
|
# to be called just before protected mode transition
|
|
default_switch:
|
|
cli # no interrupts allowed !
|
|
movb $0x80, %al # disable NMI for bootup
|
|
# sequence
|
|
outb %al, $0x70
|
|
lret
|
|
|
|
|
|
# This routine checks that the keyboard command queue is empty
|
|
# (after emptying the output buffers)
|
|
#
|
|
# Some machines have delusions that the keyboard buffer is always full
|
|
# with no keyboard attached...
|
|
#
|
|
# If there is no keyboard controller, we will usually get 0xff
|
|
# to all the reads. With each IO taking a microsecond and
|
|
# a timeout of 100,000 iterations, this can take about half a
|
|
# second ("delay" == outb to port 0x80). That should be ok,
|
|
# and should also be plenty of time for a real keyboard controller
|
|
# to empty.
|
|
#
|
|
|
|
empty_8042:
|
|
pushl %ecx
|
|
movl $100000, %ecx
|
|
|
|
empty_8042_loop:
|
|
decl %ecx
|
|
jz empty_8042_end_loop
|
|
|
|
call delay
|
|
|
|
inb $0x64, %al # 8042 status port
|
|
testb $1, %al # output buffer?
|
|
jz no_output
|
|
|
|
call delay
|
|
inb $0x60, %al # read it
|
|
jmp empty_8042_loop
|
|
|
|
no_output:
|
|
testb $2, %al # is input buffer full?
|
|
jnz empty_8042_loop # yes - loop
|
|
empty_8042_end_loop:
|
|
popl %ecx
|
|
ret
|
|
|
|
# Read the cmos clock. Return the seconds in al
|
|
gettime:
|
|
pushw %cx
|
|
movb $0x02, %ah
|
|
int $0x1a
|
|
movb %dh, %al # %dh contains the seconds
|
|
andb $0x0f, %al
|
|
movb %dh, %ah
|
|
movb $0x04, %cl
|
|
shrb %cl, %ah
|
|
aad
|
|
popw %cx
|
|
ret
|
|
|
|
# Delay is needed after doing I/O
|
|
delay:
|
|
outb %al,$0x80
|
|
ret
|
|
|
|
# Descriptor tables
|
|
gdt:
|
|
.word 0, 0, 0, 0 # dummy
|
|
|
|
.word 0, 0, 0, 0 # unused
|
|
|
|
.word 0xFFFF # 4Gb - (0x100000*0x1000 = 4Gb)
|
|
.word 0 # base address = 0
|
|
.word 0x9A00 # code read/exec
|
|
.word 0x00CF # granularity = 4096, 386
|
|
# (+5th nibble of limit)
|
|
|
|
.word 0xFFFF # 4Gb - (0x100000*0x1000 = 4Gb)
|
|
.word 0 # base address = 0
|
|
.word 0x9200 # data read/write
|
|
.word 0x00CF # granularity = 4096, 386
|
|
# (+5th nibble of limit)
|
|
gdt_end:
|
|
idt_48:
|
|
.word 0 # idt limit = 0
|
|
.word 0, 0 # idt base = 0L
|
|
gdt_48:
|
|
.word gdt_end-gdt-1 # gdt limit
|
|
.word 0, 0 # gdt base (filled in later)
|
|
|
|
# Include video setup & detection code
|
|
|
|
#include "../../i386/boot/video.S"
|
|
|
|
# Setup signature -- must be last
|
|
setup_sig1: .word SIG1
|
|
setup_sig2: .word SIG2
|
|
|
|
# After this point, there is some free space which is used by the video mode
|
|
# handling code to store the temporary mode table (not used by the kernel).
|
|
|
|
modelist:
|
|
|
|
.text
|
|
endtext:
|
|
.data
|
|
enddata:
|
|
.bss
|
|
endbss:
|