Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 867 insertions, 0 deletions

diff --git a/arch/x86_64/boot/setup.S b/arch/x86_64/boot/setup.S
new file mode 100644
index 000000000000..3e838be9dbe7
--- /dev/null
+++ b/arch/x86_64/boot/setup.S
@@ -0,0 +1,867 @@
+/*
+ *      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 dont 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 <linux/config.h>
+#include <asm/segment.h>
+#include <linux/version.h>
+#include <linux/compile.h>
+#include <asm/boot.h>
+#include <asm/e820.h>
+#include <asm/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   0x0203          # 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
+        
+trampoline:     call    start_of_setup
+                .align 16
+                                        # The offset at this point is 0x240
+                .space  (0x7ff-0x240+1) # E820 & EDD space (ending at 0x7ff)
+# 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
+        
+        /* minimum CPUID flags for x86-64 */
+        /* see http://www.x86-64.org/lists/discuss/msg02971.html */             
+#define SSE_MASK ((1<<25)|(1<<26))
+#define REQUIRED_MASK1 ((1<<0)|(1<<3)|(1<<4)|(1<<5)|(1<<6)|(1<<8)|\
+                                           (1<<13)|(1<<15)|(1<<24))
+#define REQUIRED_MASK2 (1<<29)
+
+        pushfl                          /* standard way to check for cpuid */
+        popl    %eax
+        movl    %eax,%ebx
+        xorl    $0x200000,%eax
+        pushl   %eax
+        popfl
+        pushfl
+        popl    %eax
+        cmpl    %eax,%ebx
+        jz      no_longmode             /* cpu has no cpuid */
+        movl    $0x0,%eax
+        cpuid
+        cmpl    $0x1,%eax
+        jb      no_longmode             /* no cpuid 1 */
+        xor     %di,%di
+        cmpl    $0x68747541,%ebx        /* AuthenticAMD */
+        jnz     noamd
+        cmpl    $0x69746e65,%edx
+        jnz     noamd
+        cmpl    $0x444d4163,%ecx
+        jnz     noamd
+        mov     $1,%di                  /* cpu is from AMD */
+noamd:          
+        movl    $0x1,%eax
+        cpuid
+        andl    $REQUIRED_MASK1,%edx
+        xorl    $REQUIRED_MASK1,%edx
+        jnz     no_longmode
+        movl    $0x80000000,%eax
+        cpuid
+        cmpl    $0x80000001,%eax
+        jb      no_longmode             /* no extended cpuid */
+        movl    $0x80000001,%eax
+        cpuid
+        andl    $REQUIRED_MASK2,%edx
+        xorl    $REQUIRED_MASK2,%edx
+        jnz     no_longmode
+sse_test:               
+        movl    $1,%eax
+        cpuid
+        andl    $SSE_MASK,%edx
+        cmpl    $SSE_MASK,%edx
+        je      sse_ok
+        test    %di,%di
+        jz      no_longmode     /* only try to force SSE on AMD */ 
+        movl    $0xc0010015,%ecx        /* HWCR */
+        rdmsr
+        btr     $15,%eax        /* enable SSE */
+        wrmsr
+        xor     %di,%di         /* don't loop */
+        jmp     sse_test        /* try again */ 
+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
+        
+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.teleport.com/~acpi/acpihtml/topic245.htm
+
+#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 32 entries
+        cmpb    $E820MAX, %al
+        jnl     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 dont 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
+        movw    $0, (0x1ff)                     # default is no pointing device
+        int     $0x11                           # int 0x11: equipment list
+        testb   $0x04, %al                      # check if mouse installed
+        jz      no_psmouse
+
+        movw    $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 operant 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)
+idt_48:
+        .word   0                               # idt limit = 0
+        .word   0, 0                            # idt base = 0L
+gdt_48:
+        .word   0x8000                          # gdt limit=2048,
+                                                #  256 GDT entries
+
+        .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: