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diff --git a/arch/i386/boot/edd.S b/arch/i386/boot/edd.S
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-/*
- * BIOS Enhanced Disk Drive support
- * Copyright (C) 2002, 2003, 2004 Dell, Inc.
- * by Matt Domsch <Matt_Domsch@dell.com> October 2002
- * conformant to T13 Committee www.t13.org
- * projects 1572D, 1484D, 1386D, 1226DT
- * disk signature read by Matt Domsch <Matt_Domsch@dell.com>
- * and Andrew Wilks <Andrew_Wilks@dell.com> September 2003, June 2004
- * legacy CHS retrieval by Patrick J. LoPresti <patl@users.sourceforge.net>
- * March 2004
- * Command line option parsing, Matt Domsch, November 2004
- */
-
-#include <linux/edd.h>
-#include <asm/setup.h>
-
-#if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE)
-
-# It is assumed that %ds == INITSEG here
-
- movb $0, (EDD_MBR_SIG_NR_BUF)
- movb $0, (EDDNR)
-
-# Check the command line for options:
-# edd=of disables EDD completely (edd=off)
-# edd=sk skips the MBR test (edd=skipmbr)
-# edd=on re-enables EDD (edd=on)
-
- pushl %esi
- movw $edd_mbr_sig_start, %di # Default to edd=on
-
- movl %cs:(cmd_line_ptr), %esi
- andl %esi, %esi
- jz old_cl # Old boot protocol?
-
-# Convert to a real-mode pointer in fs:si
- movl %esi, %eax
- shrl $4, %eax
- movw %ax, %fs
- andw $0xf, %si
- jmp have_cl_pointer
-
-# Old-style boot protocol?
-old_cl:
- push %ds # aka INITSEG
- pop %fs
-
- cmpw $0xa33f, (0x20)
- jne done_cl # No command line at all?
- movw (0x22), %si # Pointer relative to INITSEG
-
-# fs:si has the pointer to the command line now
-have_cl_pointer:
-
-# Loop through kernel command line one byte at a time. Just in
-# case the loader is buggy and failed to null-terminate the command line
-# terminate if we get close enough to the end of the segment that we
-# cannot fit "edd=XX"...
-cl_atspace:
- cmpw $-5, %si # Watch for segment wraparound
- jae done_cl
- movl %fs:(%si), %eax
- andb %al, %al # End of line?
- jz done_cl
- cmpl $EDD_CL_EQUALS, %eax
- jz found_edd_equals
- cmpb $0x20, %al # <= space consider whitespace
- ja cl_skipword
- incw %si
- jmp cl_atspace
-
-cl_skipword:
- cmpw $-5, %si # Watch for segment wraparound
- jae done_cl
- movb %fs:(%si), %al # End of string?
- andb %al, %al
- jz done_cl
- cmpb $0x20, %al
- jbe cl_atspace
- incw %si
- jmp cl_skipword
-
-found_edd_equals:
-# only looking at first two characters after equals
-# late overrides early on the command line, so keep going after finding something
- movw %fs:4(%si), %ax
- cmpw $EDD_CL_OFF, %ax # edd=of
- je do_edd_off
- cmpw $EDD_CL_SKIP, %ax # edd=sk
- je do_edd_skipmbr
- cmpw $EDD_CL_ON, %ax # edd=on
- je do_edd_on
- jmp cl_skipword
-do_edd_skipmbr:
- movw $edd_start, %di
- jmp cl_skipword
-do_edd_off:
- movw $edd_done, %di
- jmp cl_skipword
-do_edd_on:
- movw $edd_mbr_sig_start, %di
- jmp cl_skipword
-
-done_cl:
- popl %esi
- jmpw *%di
-
-# Read the first sector of each BIOS disk device and store the 4-byte signature
-edd_mbr_sig_start:
- movb $0x80, %dl # from device 80
- movw $EDD_MBR_SIG_BUF, %bx # store buffer ptr in bx
-edd_mbr_sig_read:
- movl $0xFFFFFFFF, %eax
- movl %eax, (%bx) # assume failure
- pushw %bx
- movb $READ_SECTORS, %ah
- movb $1, %al # read 1 sector
- movb $0, %dh # at head 0
- movw $1, %cx # cylinder 0, sector 0
- pushw %es
- pushw %ds
- popw %es
- movw $EDDBUF, %bx # disk's data goes into EDDBUF
- pushw %dx # work around buggy BIOSes
- stc # work around buggy BIOSes
- int $0x13
- sti # work around buggy BIOSes
- popw %dx
- popw %es
- popw %bx
- jc edd_mbr_sig_done # on failure, we're done.
- cmpb $0, %ah # some BIOSes do not set CF
- jne edd_mbr_sig_done # on failure, we're done.
- movl (EDDBUF+EDD_MBR_SIG_OFFSET), %eax # read sig out of the MBR
- movl %eax, (%bx) # store success
- incb (EDD_MBR_SIG_NR_BUF) # note that we stored something
- incb %dl # increment to next device
- addw $4, %bx # increment sig buffer ptr
- cmpb $EDD_MBR_SIG_MAX, (EDD_MBR_SIG_NR_BUF) # Out of space?
- jb edd_mbr_sig_read # keep looping
-edd_mbr_sig_done:
-
-# Do the BIOS Enhanced Disk Drive calls
-# This consists of two calls:
-# int 13h ah=41h "Check Extensions Present"
-# int 13h ah=48h "Get Device Parameters"
-# int 13h ah=08h "Legacy Get Device Parameters"
-#
-# A buffer of size EDDMAXNR*(EDDEXTSIZE+EDDPARMSIZE) is reserved for our use
-# in the boot_params at EDDBUF. The first four bytes of which are
-# used to store the device number, interface support map and version
-# results from fn41. The next four bytes are used to store the legacy
-# cylinders, heads, and sectors from fn08. The following 74 bytes are used to
-# store the results from fn48. Starting from device 80h, fn41, then fn48
-# are called and their results stored in EDDBUF+n*(EDDEXTSIZE+EDDPARMIZE).
-# Then the pointer is incremented to store the data for the next call.
-# This repeats until either a device doesn't exist, or until EDDMAXNR
-# devices have been stored.
-# The one tricky part is that ds:si always points EDDEXTSIZE bytes into
-# the structure, and the fn41 and fn08 results are stored at offsets
-# from there. This removes the need to increment the pointer for
-# every store, and leaves it ready for the fn48 call.
-# A second one-byte buffer, EDDNR, in the boot_params stores
-# the number of BIOS devices which exist, up to EDDMAXNR.
-# In setup.c, copy_edd() stores both boot_params buffers away
-# for later use, as they would get overwritten otherwise.
-# This code is sensitive to the size of the structs in edd.h
-edd_start:
- # %ds points to the bootsector
- # result buffer for fn48
- movw $EDDBUF+EDDEXTSIZE, %si # in ds:si, fn41 results
- # kept just before that
- movb $0x80, %dl # BIOS device 0x80
-
-edd_check_ext:
- movb $CHECKEXTENSIONSPRESENT, %ah # Function 41
- movw $EDDMAGIC1, %bx # magic
- int $0x13 # make the call
- jc edd_done # no more BIOS devices
-
- cmpw $EDDMAGIC2, %bx # is magic right?
- jne edd_next # nope, next...
-
- movb %dl, %ds:-8(%si) # store device number
- movb %ah, %ds:-7(%si) # store version
- movw %cx, %ds:-6(%si) # store extensions
- incb (EDDNR) # note that we stored something
-
-edd_get_device_params:
- movw $EDDPARMSIZE, %ds:(%si) # put size
- movw $0x0, %ds:2(%si) # work around buggy BIOSes
- movb $GETDEVICEPARAMETERS, %ah # Function 48
- int $0x13 # make the call
- # Don't check for fail return
- # it doesn't matter.
-edd_get_legacy_chs:
- xorw %ax, %ax
- movw %ax, %ds:-4(%si)
- movw %ax, %ds:-2(%si)
- # Ralf Brown's Interrupt List says to set ES:DI to
- # 0000h:0000h "to guard against BIOS bugs"
- pushw %es
- movw %ax, %es
- movw %ax, %di
- pushw %dx # legacy call clobbers %dl
- movb $LEGACYGETDEVICEPARAMETERS, %ah # Function 08
- int $0x13 # make the call
- jc edd_legacy_done # failed
- movb %cl, %al # Low 6 bits are max
- andb $0x3F, %al # sector number
- movb %al, %ds:-1(%si) # Record max sect
- movb %dh, %ds:-2(%si) # Record max head number
- movb %ch, %al # Low 8 bits of max cyl
- shr $6, %cl
- movb %cl, %ah # High 2 bits of max cyl
- movw %ax, %ds:-4(%si)
-
-edd_legacy_done:
- popw %dx
- popw %es
- movw %si, %ax # increment si
- addw $EDDPARMSIZE+EDDEXTSIZE, %ax
- movw %ax, %si
-
-edd_next:
- incb %dl # increment to next device
- cmpb $EDDMAXNR, (EDDNR) # Out of space?
- jb edd_check_ext # keep looping
-
-edd_done:
-#endif