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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/i386/boot/edd.S
downloadconfigs-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz
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!
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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 retreival 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)
+ movb $0, (EDD_MBR_SIG_NR_BUF)
+ movb $0, (EDDNR)
+
+# Check the command line for two options:
+# edd=of disables EDD completely (edd=off)
+# edd=sk skips the MBR test (edd=skipmbr)
+ pushl %esi
+ cmpl $0, %cs:cmd_line_ptr
+ jz done_cl
+ movl %cs:(cmd_line_ptr), %esi
+# ds:esi has the pointer to the command line now
+ movl $(COMMAND_LINE_SIZE-7), %ecx
+# loop through kernel command line one byte at a time
+cl_loop:
+ cmpl $EDD_CL_EQUALS, (%si)
+ jz found_edd_equals
+ incl %esi
+ loop cl_loop
+ jmp done_cl
+found_edd_equals:
+# only looking at first two characters after equals
+ addl $4, %esi
+ cmpw $EDD_CL_OFF, (%si) # edd=of
+ jz do_edd_off
+ cmpw $EDD_CL_SKIP, (%si) # edd=sk
+ jz do_edd_skipmbr
+ jmp done_cl
+do_edd_skipmbr:
+ popl %esi
+ jmp edd_start
+do_edd_off:
+ popl %esi
+ jmp edd_done
+done_cl:
+ popl %esi
+
+
+# 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.
+ 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