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-rw-r--r--arch/i386/boot/setup.S1075
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diff --git a/arch/i386/boot/setup.S b/arch/i386/boot/setup.S
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+++ /dev/null
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-/*
- * 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>
- *
- * New A20 code ported from SYSLINUX by H. Peter Anvin. AMD Elan bugfixes
- * by Robert Schwebel, December 2001 <robert@schwebel.de>
- */
-
-#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 (-__PAGE_OFFSET-(512 << 20)-1) & 0x7fffffff
- # (Header version 0x0203 or later)
- # The highest safe address for
- # the contents of an initrd
-
-kernel_alignment: .long CONFIG_PHYSICAL_ALIGN #physical addr alignment
- #required for protected mode
- #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)
-
-# Part of above routine, this one just prints ascii al
-prtchr: pushw %ax
- pushw %cx
- movw $7,%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
- pushw %cs
- popw %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:
- hlt
- 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..."
-
-# check minimum cpuid
-# we do this here because it is the last place we can actually
-# show a user visible error message. Later the video modus
-# might be already messed up.
-loader_ok:
- call verify_cpu
- testl %eax,%eax
- jz cpu_ok
- movw %cs,%ax # aka SETUPSEG
- movw %ax,%ds
- lea cpu_panic_mess,%si
- call prtstr
-1: jmp 1b
-
-cpu_panic_mess:
- .asciz "PANIC: CPU too old for this kernel."
-
-#include "../kernel/verify_cpu.S"
-
-cpu_ok:
-# 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 Micro Channel (MCA) bus
- movw %cs, %ax # aka SETUPSEG
- subw $DELTA_INITSEG, %ax # aka INITSEG
- movw %ax, %ds
- xorw %ax, %ax
- movw %ax, (0xa0) # set table length to 0
- movb $0xc0, %ah
- stc
- int $0x15 # moves feature table to es:bx
- jc no_mca
-
- pushw %ds
- movw %es, %ax
- movw %ax, %ds
- movw %cs, %ax # aka SETUPSEG
- subw $DELTA_INITSEG, %ax # aka INITSEG
- movw %ax, %es
- movw %bx, %si
- movw $0xa0, %di
- movw (%si), %cx
- addw $2, %cx # table length is a short
- cmpw $0x10, %cx
- jc sysdesc_ok
-
- movw $0x10, %cx # we keep only first 16 bytes
-sysdesc_ok:
- rep
- movsb
- popw %ds
-no_mca:
-#ifdef CONFIG_X86_VOYAGER
- movb $0xff, 0x40 # flag on config found
- movb $0xc0, %al
- mov $0xff, %ah
- int $0x15 # put voyager config info at es:di
- jc no_voyager
- movw $0x40, %si # place voyager info in apm table
- cld
- movw $7, %cx
-voyager_rep:
- movb %es:(%di), %al
- movb %al,(%si)
- incw %di
- incw %si
- decw %cx
- jnz voyager_rep
-no_voyager:
-#endif
-# 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:
-
-#if defined(CONFIG_X86_SPEEDSTEP_SMI) || defined(CONFIG_X86_SPEEDSTEP_SMI_MODULE)
- movl $0x0000E980, %eax # IST Support
- movl $0x47534943, %edx # Request value
- int $0x15
-
- movl %eax, (96)
- movl %ebx, (100)
- movl %ecx, (104)
- movl %edx, (108)
-#endif
-
-#if defined(CONFIG_APM) || defined(CONFIG_APM_MODULE)
-# Then check for an APM BIOS...
- # %ds points to the bootsector
- movw $0, 0x40 # version = 0 means no APM BIOS
- movw $0x05300, %ax # APM BIOS installation check
- xorw %bx, %bx
- int $0x15
- jc done_apm_bios # Nope, no APM BIOS
-
- cmpw $0x0504d, %bx # Check for "PM" signature
- jne done_apm_bios # No signature, no APM BIOS
-
- andw $0x02, %cx # Is 32 bit supported?
- je done_apm_bios # No 32-bit, no (good) APM BIOS
-
- movw $0x05304, %ax # Disconnect first just in case
- xorw %bx, %bx
- int $0x15 # ignore return code
- movw $0x05303, %ax # 32 bit connect
- xorl %ebx, %ebx
- xorw %cx, %cx # paranoia :-)
- xorw %dx, %dx # ...
- xorl %esi, %esi # ...
- xorw %di, %di # ...
- int $0x15
- jc no_32_apm_bios # Ack, error.
-
- movw %ax, (66) # BIOS code segment
- movl %ebx, (68) # BIOS entry point offset
- movw %cx, (72) # BIOS 16 bit code segment
- movw %dx, (74) # BIOS data segment
- movl %esi, (78) # BIOS code segment lengths
- movw %di, (82) # BIOS data segment length
-# Redo the installation check as the 32 bit connect
-# modifies the flags returned on some BIOSs
- movw $0x05300, %ax # APM BIOS installation check
- xorw %bx, %bx
- xorw %cx, %cx # paranoia
- int $0x15
- jc apm_disconnect # error -> shouldn't happen
-
- cmpw $0x0504d, %bx # check for "PM" signature
- jne apm_disconnect # no sig -> shouldn't happen
-
- movw %ax, (64) # record the APM BIOS version
- movw %cx, (76) # and flags
- jmp done_apm_bios
-
-apm_disconnect: # Tidy up
- movw $0x05304, %ax # Disconnect
- xorw %bx, %bx
- int $0x15 # ignore return code
-
- jmp done_apm_bios
-
-no_32_apm_bios:
- andw $0xfffd, (76) # remove 32 bit support bit
-done_apm_bios:
-#endif
-
-#include "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:
-# 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
-
-#
-# Enable A20. This is at the very best an annoying procedure.
-# A20 code ported from SYSLINUX 1.52-1.63 by H. Peter Anvin.
-# AMD Elan bug fix by Robert Schwebel.
-#
-
-#if defined(CONFIG_X86_ELAN)
- movb $0x02, %al # alternate A20 gate
- outb %al, $0x92 # this works on SC410/SC520
-a20_elan_wait:
- call a20_test
- jz a20_elan_wait
- jmp a20_done
-#endif
-
-
-A20_TEST_LOOPS = 32 # Iterations per wait
-A20_ENABLE_LOOPS = 255 # Total loops to try
-
-
-#ifndef CONFIG_X86_VOYAGER
-a20_try_loop:
-
- # First, see if we are on a system with no A20 gate.
-a20_none:
- call a20_test
- jnz a20_done
-
- # Next, try the BIOS (INT 0x15, AX=0x2401)
-a20_bios:
- movw $0x2401, %ax
- pushfl # Be paranoid about flags
- int $0x15
- popfl
-
- call a20_test
- jnz a20_done
-
- # Try enabling A20 through the keyboard controller
-#endif /* CONFIG_X86_VOYAGER */
-a20_kbc:
- call empty_8042
-
-#ifndef CONFIG_X86_VOYAGER
- call a20_test # Just in case the BIOS worked
- jnz a20_done # but had a delayed reaction.
-#endif
-
- movb $0xD1, %al # command write
- outb %al, $0x64
- call empty_8042
-
- movb $0xDF, %al # A20 on
- outb %al, $0x60
- call empty_8042
-
-#ifndef CONFIG_X86_VOYAGER
- # 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.
-a20_kbc_wait:
- xorw %cx, %cx
-a20_kbc_wait_loop:
- call a20_test
- jnz a20_done
- loop a20_kbc_wait_loop
-
- # Final attempt: use "configuration port A"
-a20_fast:
- inb $0x92, %al # Configuration Port A
- orb $0x02, %al # "fast A20" version
- andb $0xFE, %al # don't accidentally reset
- outb %al, $0x92
-
- # Wait for configuration port A to take effect
-a20_fast_wait:
- xorw %cx, %cx
-a20_fast_wait_loop:
- call a20_test
- jnz a20_done
- loop a20_fast_wait_loop
-
- # A20 is still not responding. Try frobbing it again.
- #
- decb (a20_tries)
- jnz a20_try_loop
-
- movw $a20_err_msg, %si
- call prtstr
-
-a20_die:
- hlt
- jmp a20_die
-
-a20_tries:
- .byte A20_ENABLE_LOOPS
-
-a20_err_msg:
- .ascii "linux: fatal error: A20 gate not responding!"
- .byte 13, 10, 0
-
- # If we get here, all is good
-a20_done:
-
-#endif /* CONFIG_X86_VOYAGER */
-# set up gdt and idt and 32bit start address
- 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 %eax, code32
- addl $gdt, %eax
- movl %eax, (gdt_48+2)
- lgdt gdt_48 # load gdt with whatever is
- # appropriate
-
-# 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
-
-# jump to startup_32 in arch/i386/boot/compressed/head.S
-#
-# NOTE: For high loaded big kernels we need a
-# jmpi 0x100000,__BOOT_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 startup_32 # will be set to %cs+startup_32
- .word __BOOT_CS
-.code32
-startup_32:
- movl $(__BOOT_DS), %eax
- movl %eax, %ds
- movl %eax, %es
- movl %eax, %fs
- movl %eax, %gs
- movl %eax, %ss
-
- xorl %eax, %eax
-1: incl %eax # check that A20 really IS enabled
- movl %eax, 0x00000000 # loop forever if it isn't
- cmpl %eax, 0x00100000
- je 1b
-
- # Jump to the 32bit entry point
- jmpl *(code32_start - start + (DELTA_INITSEG << 4))(%esi)
-.code16
-
-# 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
-
-
-#ifndef CONFIG_X86_VOYAGER
-# This routine tests whether or not A20 is enabled. If so, it
-# exits with zf = 0.
-#
-# The memory address used, 0x200, is the int $0x80 vector, which
-# should be safe.
-
-A20_TEST_ADDR = 4*0x80
-
-a20_test:
- pushw %cx
- pushw %ax
- xorw %cx, %cx
- movw %cx, %fs # Low memory
- decw %cx
- movw %cx, %gs # High memory area
- movw $A20_TEST_LOOPS, %cx
- movw %fs:(A20_TEST_ADDR), %ax
- pushw %ax
-a20_test_wait:
- incw %ax
- movw %ax, %fs:(A20_TEST_ADDR)
- call delay # Serialize and make delay constant
- cmpw %gs:(A20_TEST_ADDR+0x10), %ax
- loope a20_test_wait
-
- popw %fs:(A20_TEST_ADDR)
- popw %ax
- popw %cx
- ret
-
-#endif /* CONFIG_X86_VOYAGER */
-
-# 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
-#
-# NOTE: The intel manual says gdt should be sixteen bytes aligned for
-# efficiency reasons. However, there are machines which are known not
-# to boot with misaligned GDTs, so alter this at your peril! If you alter
-# GDT_ENTRY_BOOT_CS (in asm/segment.h) remember to leave at least two
-# empty GDT entries (one for NULL and one reserved).
-#
-# NOTE: On some CPUs, the GDT must be 8 byte aligned. This is
-# true for the Voyager Quad CPU card which will not boot without
-# This directive. 16 byte aligment is recommended by intel.
-#
- .align 16
-gdt:
- .fill GDT_ENTRY_BOOT_CS,8,0
-
- .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:
- .align 4
-
- .word 0 # alignment byte
-idt_48:
- .word 0 # idt limit = 0
- .word 0, 0 # idt base = 0L
-
- .word 0 # alignment byte
-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: