arch/x86_64/boot/setup.S - kernel/msm-4.9 - Gitiles

 /*
  *	setup.S		Copyright (C) 1991, 1992 Linus Torvalds
  *
  * setup.s is responsible for getting the system data from the BIOS,
  * and putting them into the appropriate places in system memory.
  * both setup.s and system has been loaded by the bootblock.
  *
  * This code asks the bios for memory/disk/other parameters, and
  * puts them in a "safe" place: 0x90000-0x901FF, ie where the
  * boot-block used to be. It is then up to the protected mode
  * system to read them from there before the area is overwritten
  * for buffer-blocks.
  *
  * Move PS/2 aux init code to psaux.c
  * (troyer@saifr00.cfsat.Honeywell.COM) 03Oct92
  *
  * some changes and additional features by Christoph Niemann,
  * March 1993/June 1994 (Christoph.Niemann@linux.org)
  *
  * add APM BIOS checking by Stephen Rothwell, May 1994
  * (sfr@canb.auug.org.au)
  *
  * High load stuff, initrd support and position independency
  * by Hans Lermen & Werner Almesberger, February 1996
  * <lermen@elserv.ffm.fgan.de>, <almesber@lrc.epfl.ch>
  *
  * Video handling moved to video.S by Martin Mares, March 1996
  * <mj@k332.feld.cvut.cz>
  *
  * Extended memory detection scheme retwiddled by orc@pell.chi.il.us (david
  * parsons) to avoid loadlin confusion, July 1997
  *
  * Transcribed from Intel (as86) -> AT&T (gas) by Chris Noe, May 1999.
  * <stiker@northlink.com>
  *
  * Fix to work around buggy BIOSes which don't use carry bit correctly
  * and/or report extended memory in CX/DX for e801h memory size detection
  * call.  As a result the kernel got wrong figures.  The int15/e801h docs
  * from Ralf Brown interrupt list seem to indicate AX/BX should be used
  * anyway.  So to avoid breaking many machines (presumably there was a reason
  * to orginally use CX/DX instead of AX/BX), we do a kludge to see
  * if CX/DX have been changed in the e801 call and if so use AX/BX .
  * Michael Miller, April 2001 <michaelm@mjmm.org>
  *
  * Added long mode checking and SSE force. March 2003, Andi Kleen.
  */

 #include <asm/segment.h>
 #include <linux/utsrelease.h>
 #include <linux/compile.h>
 #include <asm/boot.h>
 #include <asm/e820.h>
 #include <asm/page.h>
 #include <asm/setup.h>

 /* Signature words to ensure LILO loaded us right */
 #define SIG1	0xAA55
 #define SIG2	0x5A5A

 INITSEG  = DEF_INITSEG		# 0x9000, we move boot here, out of the way
 SYSSEG   = DEF_SYSSEG		# 0x1000, system loaded at 0x10000 (65536).
 SETUPSEG = DEF_SETUPSEG		# 0x9020, this is the current segment
 				# ... and the former contents of CS

 DELTA_INITSEG = SETUPSEG - INITSEG	# 0x0020

 .code16
 .globl begtext, begdata, begbss, endtext, enddata, endbss

 .text
 begtext:
 .data
 begdata:
 .bss
 begbss:
 .text

 start:
 	jmp	trampoline

 # This is the setup header, and it must start at %cs:2 (old 0x9020:2)

 		.ascii	"HdrS"		# header signature
 		.word	0x0206		# header version number (>= 0x0105)
 					# or else old loadlin-1.5 will fail)
 realmode_swtch:	.word	0, 0		# default_switch, SETUPSEG
 start_sys_seg:	.word	SYSSEG
 		.word	kernel_version	# pointing to kernel version string
 					# above section of header is compatible
 					# with loadlin-1.5 (header v1.5). Don't
 					# change it.

 type_of_loader:	.byte	0		# = 0, old one (LILO, Loadlin,
 					#      Bootlin, SYSLX, bootsect...)
 					# See Documentation/i386/boot.txt for
 					# assigned ids

 # flags, unused bits must be zero (RFU) bit within loadflags
 loadflags:
 LOADED_HIGH	= 1			# If set, the kernel is loaded high
 CAN_USE_HEAP	= 0x80			# If set, the loader also has set
 					# heap_end_ptr to tell how much
 					# space behind setup.S can be used for
 					# heap purposes.
 					# Only the loader knows what is free
 #ifndef __BIG_KERNEL__
 		.byte	0
 #else
 		.byte	LOADED_HIGH
 #endif

 setup_move_size: .word  0x8000		# size to move, when setup is not
 					# loaded at 0x90000. We will move setup
 					# to 0x90000 then just before jumping
 					# into the kernel. However, only the
 					# loader knows how much data behind
 					# us also needs to be loaded.

 code32_start:				# here loaders can put a different
 					# start address for 32-bit code.
 #ifndef __BIG_KERNEL__
 		.long	0x1000		#   0x1000 = default for zImage
 #else
 		.long	0x100000	# 0x100000 = default for big kernel
 #endif

 ramdisk_image:	.long	0		# address of loaded ramdisk image
 					# Here the loader puts the 32-bit
 					# address where it loaded the image.
 					# This only will be read by the kernel.

 ramdisk_size:	.long	0		# its size in bytes

 bootsect_kludge:
 		.long	0		# obsolete

 heap_end_ptr:	.word	modelist+1024	# (Header version 0x0201 or later)
 					# space from here (exclusive) down to
 					# end of setup code can be used by setup
 					# for local heap purposes.

 pad1:		.word	0
 cmd_line_ptr:	.long 0			# (Header version 0x0202 or later)
 					# If nonzero, a 32-bit pointer
 					# to the kernel command line.
 					# The command line should be
 					# located between the start of
 					# setup and the end of low
 					# memory (0xa0000), or it may
 					# get overwritten before it
 					# gets read.  If this field is
 					# used, there is no longer
 					# anything magical about the
 					# 0x90000 segment; the setup
 					# can be located anywhere in
 					# low memory 0x10000 or higher.

 ramdisk_max:	.long 0xffffffff
 kernel_alignment:  .long 0x200000       # physical addr alignment required for
 					# protected mode relocatable kernel
 #ifdef CONFIG_RELOCATABLE
 relocatable_kernel:    .byte 1
 #else
 relocatable_kernel:    .byte 0
 #endif
 pad2:                  .byte 0
 pad3:                  .word 0

 cmdline_size:   .long   COMMAND_LINE_SIZE-1     #length of the command line,
                                                 #added with boot protocol
                                                 #version 2.06

 trampoline:	call	start_of_setup
 		.align 16
 					# The offset at this point is 0x240
 		.space  (0xeff-0x240+1)	# E820 & EDD space (ending at 0xeff)
 # End of setup header #####################################################

 start_of_setup:
 # Bootlin depends on this being done early
 	movw	$0x01500, %ax
 	movb	$0x81, %dl
 	int	$0x13

 #ifdef SAFE_RESET_DISK_CONTROLLER
 # Reset the disk controller.
 	movw	$0x0000, %ax
 	movb	$0x80, %dl
 	int	$0x13
 #endif

 # Set %ds = %cs, we know that SETUPSEG = %cs at this point
 	movw	%cs, %ax		# aka SETUPSEG
 	movw	%ax, %ds
 # Check signature at end of setup
 	cmpw	$SIG1, setup_sig1
 	jne	bad_sig

 	cmpw	$SIG2, setup_sig2
 	jne	bad_sig

 	jmp	good_sig1

 # Routine to print asciiz string at ds:si
 prtstr:
 	lodsb
 	andb	%al, %al
 	jz	fin

 	call	prtchr
 	jmp	prtstr

 fin:	ret

 # Space printing
 prtsp2:	call	prtspc		# Print double space
 prtspc:	movb	$0x20, %al	# Print single space (note: fall-thru)

 prtchr:
 	pushw	%ax
 	pushw	%cx
 	movw	$0007,%bx
 	movw	$0x01, %cx
 	movb	$0x0e, %ah
 	int	$0x10
 	popw	%cx
 	popw	%ax
 	ret

 beep:	movb	$0x07, %al
 	jmp	prtchr

 no_sig_mess: .string	"No setup signature found ..."

 good_sig1:
 	jmp	good_sig

 # We now have to find the rest of the setup code/data
 bad_sig:
 	movw	%cs, %ax			# SETUPSEG
 	subw	$DELTA_INITSEG, %ax		# INITSEG
 	movw	%ax, %ds
 	xorb	%bh, %bh
 	movb	(497), %bl			# get setup sect from bootsect
 	subw	$4, %bx				# LILO loads 4 sectors of setup
 	shlw	$8, %bx				# convert to words (1sect=2^8 words)
 	movw	%bx, %cx
 	shrw	$3, %bx				# convert to segment
 	addw	$SYSSEG, %bx
 	movw	%bx, %cs:start_sys_seg
 # Move rest of setup code/data to here
 	movw	$2048, %di			# four sectors loaded by LILO
 	subw	%si, %si
 	movw	%cs, %ax			# aka SETUPSEG
 	movw	%ax, %es
 	movw	$SYSSEG, %ax
 	movw	%ax, %ds
 	rep
 	movsw
 	movw	%cs, %ax			# aka SETUPSEG
 	movw	%ax, %ds
 	cmpw	$SIG1, setup_sig1
 	jne	no_sig

 	cmpw	$SIG2, setup_sig2
 	jne	no_sig

 	jmp	good_sig

 no_sig:
 	lea	no_sig_mess, %si
 	call	prtstr

 no_sig_loop:
 	jmp	no_sig_loop

 good_sig:
 	movw	%cs, %ax			# aka SETUPSEG
 	subw	$DELTA_INITSEG, %ax 		# aka INITSEG
 	movw	%ax, %ds
 # Check if an old loader tries to load a big-kernel
 	testb	$LOADED_HIGH, %cs:loadflags	# Do we have a big kernel?
 	jz	loader_ok			# No, no danger for old loaders.

 	cmpb	$0, %cs:type_of_loader 		# Do we have a loader that
 						# can deal with us?
 	jnz	loader_ok			# Yes, continue.

 	pushw	%cs				# No, we have an old loader,
 	popw	%ds				# die.
 	lea	loader_panic_mess, %si
 	call	prtstr

 	jmp	no_sig_loop

 loader_panic_mess: .string "Wrong loader, giving up..."

 loader_ok:
 	/* check for long mode. */
 	/* we have to do this before the VESA setup, otherwise the user
 	   can't see the error message. */

 	pushw	%ds
 	movw	%cs,%ax
 	movw	%ax,%ds

 	call verify_cpu
 	testl %eax,%eax
 	jz sse_ok

 no_longmode:
 	call	beep
 	lea	long_mode_panic,%si
 	call	prtstr
 no_longmode_loop:
 	jmp	no_longmode_loop
 long_mode_panic:
 	.string "Your CPU does not support long mode. Use a 32bit distribution."
 	.byte 0

 #include "../kernel/verify_cpu.S"
 sse_ok:
 	popw	%ds

 # tell BIOS we want to go to long mode
 	movl  $0xec00,%eax	# declare target operating mode
 	movl  $2,%ebx		# long mode
 	int $0x15

 # Get memory size (extended mem, kB)

 	xorl	%eax, %eax
 	movl	%eax, (0x1e0)
 #ifndef STANDARD_MEMORY_BIOS_CALL
 	movb	%al, (E820NR)
 # Try three different memory detection schemes.  First, try
 # e820h, which lets us assemble a memory map, then try e801h,
 # which returns a 32-bit memory size, and finally 88h, which
 # returns 0-64m

 # method E820H:
 # the memory map from hell.  e820h returns memory classified into
 # a whole bunch of different types, and allows memory holes and
 # everything.  We scan through this memory map and build a list
 # of the first 32 memory areas, which we return at [E820MAP].
 # This is documented at http://www.acpi.info/, in the ACPI 2.0 specification.

 #define SMAP  0x534d4150

 meme820:
 	xorl	%ebx, %ebx			# continuation counter
 	movw	$E820MAP, %di			# point into the whitelist
 						# so we can have the bios
 						# directly write into it.

 jmpe820:
 	movl	$0x0000e820, %eax		# e820, upper word zeroed
 	movl	$SMAP, %edx			# ascii 'SMAP'
 	movl	$20, %ecx			# size of the e820rec
 	pushw	%ds				# data record.
 	popw	%es
 	int	$0x15				# make the call
 	jc	bail820				# fall to e801 if it fails

 	cmpl	$SMAP, %eax			# check the return is `SMAP'
 	jne	bail820				# fall to e801 if it fails

 #	cmpl	$1, 16(%di)			# is this usable memory?
 #	jne	again820

 	# If this is usable memory, we save it by simply advancing %di by
 	# sizeof(e820rec).
 	#
 good820:
 	movb	(E820NR), %al			# up to 128 entries
 	cmpb	$E820MAX, %al
 	jae	bail820

 	incb	(E820NR)
 	movw	%di, %ax
 	addw	$20, %ax
 	movw	%ax, %di
 again820:
 	cmpl	$0, %ebx			# check to see if
 	jne	jmpe820				# %ebx is set to EOF
 bail820:


 # method E801H:
 # memory size is in 1k chunksizes, to avoid confusing loadlin.
 # we store the 0xe801 memory size in a completely different place,
 # because it will most likely be longer than 16 bits.
 # (use 1e0 because that's what Larry Augustine uses in his
 # alternative new memory detection scheme, and it's sensible
 # to write everything into the same place.)

 meme801:
 	stc					# fix to work around buggy
 	xorw	%cx,%cx				# BIOSes which don't clear/set
 	xorw	%dx,%dx				# carry on pass/error of
 						# e801h memory size call
 						# or merely pass cx,dx though
 						# without changing them.
 	movw	$0xe801, %ax
 	int	$0x15
 	jc	mem88

 	cmpw	$0x0, %cx			# Kludge to handle BIOSes
 	jne	e801usecxdx			# which report their extended
 	cmpw	$0x0, %dx			# memory in AX/BX rather than
 	jne	e801usecxdx			# CX/DX.  The spec I have read
 	movw	%ax, %cx			# seems to indicate AX/BX
 	movw	%bx, %dx			# are more reasonable anyway...

 e801usecxdx:
 	andl	$0xffff, %edx			# clear sign extend
 	shll	$6, %edx			# and go from 64k to 1k chunks
 	movl	%edx, (0x1e0)			# store extended memory size
 	andl	$0xffff, %ecx			# clear sign extend
  	addl	%ecx, (0x1e0)			# and add lower memory into
 						# total size.

 # Ye Olde Traditional Methode.  Returns the memory size (up to 16mb or
 # 64mb, depending on the bios) in ax.
 mem88:

 #endif
 	movb	$0x88, %ah
 	int	$0x15
 	movw	%ax, (2)

 # Set the keyboard repeat rate to the max
 	movw	$0x0305, %ax
 	xorw	%bx, %bx
 	int	$0x16

 # Check for video adapter and its parameters and allow the
 # user to browse video modes.
 	call	video				# NOTE: we need %ds pointing
 						# to bootsector

 # Get hd0 data...
 	xorw	%ax, %ax
 	movw	%ax, %ds
 	ldsw	(4 * 0x41), %si
 	movw	%cs, %ax			# aka SETUPSEG
 	subw	$DELTA_INITSEG, %ax		# aka INITSEG
 	pushw	%ax
 	movw	%ax, %es
 	movw	$0x0080, %di
 	movw	$0x10, %cx
 	pushw	%cx
 	cld
 	rep
  	movsb
 # Get hd1 data...
 	xorw	%ax, %ax
 	movw	%ax, %ds
 	ldsw	(4 * 0x46), %si
 	popw	%cx
 	popw	%es
 	movw	$0x0090, %di
 	rep
 	movsb
 # Check that there IS a hd1 :-)
 	movw	$0x01500, %ax
 	movb	$0x81, %dl
 	int	$0x13
 	jc	no_disk1

 	cmpb	$3, %ah
 	je	is_disk1

 no_disk1:
 	movw	%cs, %ax			# aka SETUPSEG
 	subw	$DELTA_INITSEG, %ax 		# aka INITSEG
 	movw	%ax, %es
 	movw	$0x0090, %di
 	movw	$0x10, %cx
 	xorw	%ax, %ax
 	cld
 	rep
 	stosb
 is_disk1:

 # Check for PS/2 pointing device
 	movw	%cs, %ax			# aka SETUPSEG
 	subw	$DELTA_INITSEG, %ax		# aka INITSEG
 	movw	%ax, %ds
 	movb	$0, (0x1ff)			# default is no pointing device
 	int	$0x11				# int 0x11: equipment list
 	testb	$0x04, %al			# check if mouse installed
 	jz	no_psmouse

 	movb	$0xAA, (0x1ff)			# device present
 no_psmouse:

 #include "../../i386/boot/edd.S"

 # Now we want to move to protected mode ...
 	cmpw	$0, %cs:realmode_swtch
 	jz	rmodeswtch_normal

 	lcall	*%cs:realmode_swtch

 	jmp	rmodeswtch_end

 rmodeswtch_normal:
         pushw	%cs
 	call	default_switch

 rmodeswtch_end:
 # we get the code32 start address and modify the below 'jmpi'
 # (loader may have changed it)
 	movl	%cs:code32_start, %eax
 	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:
	/*
	* setup.S Copyright (C) 1991, 1992 Linus Torvalds
	*
	* setup.s is responsible for getting the system data from the BIOS,
	* and putting them into the appropriate places in system memory.
	* both setup.s and system has been loaded by the bootblock.
	*
	* This code asks the bios for memory/disk/other parameters, and
	* puts them in a "safe" place: 0x90000-0x901FF, ie where the
	* boot-block used to be. It is then up to the protected mode
	* system to read them from there before the area is overwritten
	* for buffer-blocks.
	*
	* Move PS/2 aux init code to psaux.c
	* (troyer@saifr00.cfsat.Honeywell.COM) 03Oct92
	*
	* some changes and additional features by Christoph Niemann,
	* March 1993/June 1994 (Christoph.Niemann@linux.org)
	*
	* add APM BIOS checking by Stephen Rothwell, May 1994
	* (sfr@canb.auug.org.au)
	*
	* High load stuff, initrd support and position independency
	* by Hans Lermen & Werner Almesberger, February 1996
	* <lermen@elserv.ffm.fgan.de>, <almesber@lrc.epfl.ch>
	*
	* Video handling moved to video.S by Martin Mares, March 1996
	* <mj@k332.feld.cvut.cz>
	*
	* Extended memory detection scheme retwiddled by orc@pell.chi.il.us (david
	* parsons) to avoid loadlin confusion, July 1997
	*
	* Transcribed from Intel (as86) -> AT&T (gas) by Chris Noe, May 1999.
	* <stiker@northlink.com>
	*
	* Fix to work around buggy BIOSes which don't use carry bit correctly
	* and/or report extended memory in CX/DX for e801h memory size detection
	* call. As a result the kernel got wrong figures. The int15/e801h docs
	* from Ralf Brown interrupt list seem to indicate AX/BX should be used
	* anyway. So to avoid breaking many machines (presumably there was a reason
	* to orginally use CX/DX instead of AX/BX), we do a kludge to see
	* if CX/DX have been changed in the e801 call and if so use AX/BX .
	* Michael Miller, April 2001 <michaelm@mjmm.org>
	*
	* Added long mode checking and SSE force. March 2003, Andi Kleen.
	*/

	#include <asm/segment.h>
	#include <linux/utsrelease.h>
	#include <linux/compile.h>
	#include <asm/boot.h>
	#include <asm/e820.h>
	#include <asm/page.h>
	#include <asm/setup.h>

	/* Signature words to ensure LILO loaded us right */
	#define SIG1 0xAA55
	#define SIG2 0x5A5A

	INITSEG = DEF_INITSEG # 0x9000, we move boot here, out of the way
	SYSSEG = DEF_SYSSEG # 0x1000, system loaded at 0x10000 (65536).
	SETUPSEG = DEF_SETUPSEG # 0x9020, this is the current segment
	# ... and the former contents of CS

	DELTA_INITSEG = SETUPSEG - INITSEG # 0x0020

	.code16
	.globl begtext, begdata, begbss, endtext, enddata, endbss

	.text
	begtext:
	.data
	begdata:
	.bss
	begbss:
	.text

	start:
	jmp trampoline

	# This is the setup header, and it must start at %cs:2 (old 0x9020:2)

	.ascii "HdrS" # header signature
	.word 0x0206 # header version number (>= 0x0105)
	# or else old loadlin-1.5 will fail)
	realmode_swtch: .word 0, 0 # default_switch, SETUPSEG
	start_sys_seg: .word SYSSEG
	.word kernel_version # pointing to kernel version string
	# above section of header is compatible
	# with loadlin-1.5 (header v1.5). Don't
	# change it.

	type_of_loader: .byte 0 # = 0, old one (LILO, Loadlin,
	# Bootlin, SYSLX, bootsect...)
	# See Documentation/i386/boot.txt for
	# assigned ids

	# flags, unused bits must be zero (RFU) bit within loadflags
	loadflags:
	LOADED_HIGH = 1 # If set, the kernel is loaded high
	CAN_USE_HEAP = 0x80 # If set, the loader also has set
	# heap_end_ptr to tell how much
	# space behind setup.S can be used for
	# heap purposes.
	# Only the loader knows what is free
	#ifndef __BIG_KERNEL__
	.byte 0
	#else
	.byte LOADED_HIGH
	#endif

	setup_move_size: .word 0x8000 # size to move, when setup is not
	# loaded at 0x90000. We will move setup
	# to 0x90000 then just before jumping
	# into the kernel. However, only the
	# loader knows how much data behind
	# us also needs to be loaded.

	code32_start: # here loaders can put a different
	# start address for 32-bit code.
	#ifndef __BIG_KERNEL__
	.long 0x1000 # 0x1000 = default for zImage
	#else
	.long 0x100000 # 0x100000 = default for big kernel
	#endif

	ramdisk_image: .long 0 # address of loaded ramdisk image
	# Here the loader puts the 32-bit
	# address where it loaded the image.
	# This only will be read by the kernel.

	ramdisk_size: .long 0 # its size in bytes

	bootsect_kludge:
	.long 0 # obsolete

	heap_end_ptr: .word modelist+1024 # (Header version 0x0201 or later)
	# space from here (exclusive) down to
	# end of setup code can be used by setup
	# for local heap purposes.

	pad1: .word 0
	cmd_line_ptr: .long 0 # (Header version 0x0202 or later)
	# If nonzero, a 32-bit pointer
	# to the kernel command line.
	# The command line should be
	# located between the start of
	# setup and the end of low
	# memory (0xa0000), or it may
	# get overwritten before it
	# gets read. If this field is
	# used, there is no longer
	# anything magical about the
	# 0x90000 segment; the setup
	# can be located anywhere in
	# low memory 0x10000 or higher.

	ramdisk_max: .long 0xffffffff
	kernel_alignment: .long 0x200000 # physical addr alignment required for
	# protected mode relocatable kernel
	#ifdef CONFIG_RELOCATABLE
	relocatable_kernel: .byte 1
	#else
	relocatable_kernel: .byte 0
	#endif
	pad2: .byte 0
	pad3: .word 0

	cmdline_size: .long COMMAND_LINE_SIZE-1 #length of the command line,
	#added with boot protocol
	#version 2.06

	trampoline: call start_of_setup
	.align 16
	# The offset at this point is 0x240
	.space (0xeff-0x240+1) # E820 & EDD space (ending at 0xeff)
	# End of setup header #####################################################

	start_of_setup:
	# Bootlin depends on this being done early
	movw $0x01500, %ax
	movb $0x81, %dl
	int $0x13

	#ifdef SAFE_RESET_DISK_CONTROLLER
	# Reset the disk controller.
	movw $0x0000, %ax
	movb $0x80, %dl
	int $0x13
	#endif

	# Set %ds = %cs, we know that SETUPSEG = %cs at this point
	movw %cs, %ax # aka SETUPSEG
	movw %ax, %ds
	# Check signature at end of setup
	cmpw $SIG1, setup_sig1
	jne bad_sig

	cmpw $SIG2, setup_sig2
	jne bad_sig

	jmp good_sig1

	# Routine to print asciiz string at ds:si
	prtstr:
	lodsb
	andb %al, %al
	jz fin

	call prtchr
	jmp prtstr

	fin: ret

	# Space printing
	prtsp2: call prtspc # Print double space
	prtspc: movb $0x20, %al # Print single space (note: fall-thru)

	prtchr:
	pushw %ax
	pushw %cx
	movw $0007,%bx
	movw $0x01, %cx
	movb $0x0e, %ah
	int $0x10
	popw %cx
	popw %ax
	ret

	beep: movb $0x07, %al
	jmp prtchr

	no_sig_mess: .string "No setup signature found ..."

	good_sig1:
	jmp good_sig

	# We now have to find the rest of the setup code/data
	bad_sig:
	movw %cs, %ax # SETUPSEG
	subw $DELTA_INITSEG, %ax # INITSEG
	movw %ax, %ds
	xorb %bh, %bh
	movb (497), %bl # get setup sect from bootsect
	subw $4, %bx # LILO loads 4 sectors of setup
	shlw $8, %bx # convert to words (1sect=2^8 words)
	movw %bx, %cx
	shrw $3, %bx # convert to segment
	addw $SYSSEG, %bx
	movw %bx, %cs:start_sys_seg
	# Move rest of setup code/data to here
	movw $2048, %di # four sectors loaded by LILO
	subw %si, %si
	movw %cs, %ax # aka SETUPSEG
	movw %ax, %es
	movw $SYSSEG, %ax
	movw %ax, %ds
	rep
	movsw
	movw %cs, %ax # aka SETUPSEG
	movw %ax, %ds
	cmpw $SIG1, setup_sig1
	jne no_sig

	cmpw $SIG2, setup_sig2
	jne no_sig

	jmp good_sig

	no_sig:
	lea no_sig_mess, %si
	call prtstr

	no_sig_loop:
	jmp no_sig_loop

	good_sig:
	movw %cs, %ax # aka SETUPSEG
	subw $DELTA_INITSEG, %ax # aka INITSEG
	movw %ax, %ds
	# Check if an old loader tries to load a big-kernel
	testb $LOADED_HIGH, %cs:loadflags # Do we have a big kernel?
	jz loader_ok # No, no danger for old loaders.

	cmpb $0, %cs:type_of_loader # Do we have a loader that
	# can deal with us?
	jnz loader_ok # Yes, continue.

	pushw %cs # No, we have an old loader,
	popw %ds # die.
	lea loader_panic_mess, %si
	call prtstr

	jmp no_sig_loop

	loader_panic_mess: .string "Wrong loader, giving up..."

	loader_ok:
	/* check for long mode. */
	/* we have to do this before the VESA setup, otherwise the user
	can't see the error message. */

	pushw %ds
	movw %cs,%ax
	movw %ax,%ds

	call verify_cpu
	testl %eax,%eax
	jz sse_ok

	no_longmode:
	call beep
	lea long_mode_panic,%si
	call prtstr
	no_longmode_loop:
	jmp no_longmode_loop
	long_mode_panic:
	.string "Your CPU does not support long mode. Use a 32bit distribution."
	.byte 0

	#include "../kernel/verify_cpu.S"
	sse_ok:
	popw %ds

	# tell BIOS we want to go to long mode
	movl $0xec00,%eax # declare target operating mode
	movl $2,%ebx # long mode
	int $0x15

	# Get memory size (extended mem, kB)

	xorl %eax, %eax
	movl %eax, (0x1e0)
	#ifndef STANDARD_MEMORY_BIOS_CALL
	movb %al, (E820NR)
	# Try three different memory detection schemes. First, try
	# e820h, which lets us assemble a memory map, then try e801h,
	# which returns a 32-bit memory size, and finally 88h, which
	# returns 0-64m

	# method E820H:
	# the memory map from hell. e820h returns memory classified into
	# a whole bunch of different types, and allows memory holes and
	# everything. We scan through this memory map and build a list
	# of the first 32 memory areas, which we return at [E820MAP].
	# This is documented at http://www.acpi.info/, in the ACPI 2.0 specification.

	#define SMAP 0x534d4150

	meme820:
	xorl %ebx, %ebx # continuation counter
	movw $E820MAP, %di # point into the whitelist
	# so we can have the bios
	# directly write into it.

	jmpe820:
	movl $0x0000e820, %eax # e820, upper word zeroed
	movl $SMAP, %edx # ascii 'SMAP'
	movl $20, %ecx # size of the e820rec
	pushw %ds # data record.
	popw %es
	int $0x15 # make the call
	jc bail820 # fall to e801 if it fails

	cmpl $SMAP, %eax # check the return is `SMAP'
	jne bail820 # fall to e801 if it fails

	# cmpl $1, 16(%di) # is this usable memory?
	# jne again820

	# If this is usable memory, we save it by simply advancing %di by
	# sizeof(e820rec).
	#
	good820:
	movb (E820NR), %al # up to 128 entries
	cmpb $E820MAX, %al
	jae bail820

	incb (E820NR)
	movw %di, %ax
	addw $20, %ax
	movw %ax, %di
	again820:
	cmpl $0, %ebx # check to see if
	jne jmpe820 # %ebx is set to EOF
	bail820:


	# method E801H:
	# memory size is in 1k chunksizes, to avoid confusing loadlin.
	# we store the 0xe801 memory size in a completely different place,
	# because it will most likely be longer than 16 bits.
	# (use 1e0 because that's what Larry Augustine uses in his
	# alternative new memory detection scheme, and it's sensible
	# to write everything into the same place.)

	meme801:
	stc # fix to work around buggy
	xorw %cx,%cx # BIOSes which don't clear/set
	xorw %dx,%dx # carry on pass/error of
	# e801h memory size call
	# or merely pass cx,dx though
	# without changing them.
	movw $0xe801, %ax
	int $0x15
	jc mem88

	cmpw $0x0, %cx # Kludge to handle BIOSes
	jne e801usecxdx # which report their extended
	cmpw $0x0, %dx # memory in AX/BX rather than
	jne e801usecxdx # CX/DX. The spec I have read
	movw %ax, %cx # seems to indicate AX/BX
	movw %bx, %dx # are more reasonable anyway...

	e801usecxdx:
	andl $0xffff, %edx # clear sign extend
	shll $6, %edx # and go from 64k to 1k chunks
	movl %edx, (0x1e0) # store extended memory size
	andl $0xffff, %ecx # clear sign extend
	addl %ecx, (0x1e0) # and add lower memory into
	# total size.

	# Ye Olde Traditional Methode. Returns the memory size (up to 16mb or
	# 64mb, depending on the bios) in ax.
	mem88:

	#endif
	movb $0x88, %ah
	int $0x15
	movw %ax, (2)

	# Set the keyboard repeat rate to the max
	movw $0x0305, %ax
	xorw %bx, %bx
	int $0x16

	# Check for video adapter and its parameters and allow the
	# user to browse video modes.
	call video # NOTE: we need %ds pointing
	# to bootsector

	# Get hd0 data...
	xorw %ax, %ax
	movw %ax, %ds
	ldsw (4 * 0x41), %si
	movw %cs, %ax # aka SETUPSEG
	subw $DELTA_INITSEG, %ax # aka INITSEG
	pushw %ax
	movw %ax, %es
	movw $0x0080, %di
	movw $0x10, %cx
	pushw %cx
	cld
	rep
	movsb
	# Get hd1 data...
	xorw %ax, %ax
	movw %ax, %ds
	ldsw (4 * 0x46), %si
	popw %cx
	popw %es
	movw $0x0090, %di
	rep
	movsb
	# Check that there IS a hd1 :-)
	movw $0x01500, %ax
	movb $0x81, %dl
	int $0x13
	jc no_disk1

	cmpb $3, %ah
	je is_disk1

	no_disk1:
	movw %cs, %ax # aka SETUPSEG
	subw $DELTA_INITSEG, %ax # aka INITSEG
	movw %ax, %es
	movw $0x0090, %di
	movw $0x10, %cx
	xorw %ax, %ax
	cld
	rep
	stosb
	is_disk1:

	# Check for PS/2 pointing device
	movw %cs, %ax # aka SETUPSEG
	subw $DELTA_INITSEG, %ax # aka INITSEG
	movw %ax, %ds
	movb $0, (0x1ff) # default is no pointing device
	int $0x11 # int 0x11: equipment list
	testb $0x04, %al # check if mouse installed
	jz no_psmouse

	movb $0xAA, (0x1ff) # device present
	no_psmouse:

	#include "../../i386/boot/edd.S"

	# Now we want to move to protected mode ...
	cmpw $0, %cs:realmode_swtch
	jz rmodeswtch_normal

	lcall *%cs:realmode_swtch

	jmp rmodeswtch_end

	rmodeswtch_normal:
	pushw %cs
	call default_switch

	rmodeswtch_end:
	# we get the code32 start address and modify the below 'jmpi'
	# (loader may have changed it)
	movl %cs:code32_start, %eax
	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: