--- /dev/null
+/*
+ * 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 <arch/segment.h>
+#include <lwk/version.h>
+#include <lwk/compile.h>
+#include <lwk/init.h>
+#include <arch/boot.h>
+#include <arch/e820.h>
+#include <arch/page.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 "BOOT FAILURE: This system does not support x86_64 long mode."
+ .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:
+
+# 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 LWK_COMPILE_BY
+ .ascii "@"
+ .ascii LWK_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 "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:
