Revert recent EDD changes to use EXTENDED READ comand and CONFIG_EDD_SKIP_MBR

It seems to result in unexplained memory corruption. Matt is working on it.

Cset exclude: Matt_Domsch@dell.com[torvalds]|ChangeSet|20041020153622|50713

arch/i386/boot/edd.S

@@ -7,66 +7,20 @@
  *	and Andrew Wilks <Andrew_Wilks@dell.com> September 2003, June 2004
  * legacy CHS retreival by Patrick J. LoPresti <patl@users.sourceforge.net>
  *      March 2004
- * Use EXTENDED READ calls if possible, Matt Domsch, October 2004
  */
 
 #include <linux/edd.h>
 
 #if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE)
+# Read the first sector of each BIOS disk device and store the 4-byte signature
+edd_mbr_sig_start:
 	movb	$0, (EDD_MBR_SIG_NR_BUF)	# zero value at EDD_MBR_SIG_NR_BUF
-#ifndef CONFIG_EDD_SKIP_MBR
-	xorl	%edx, %edx
 	movb	$0x80, %dl			# from device 80
-
-edd_mbr_check_ext:
-	xorl	%eax, %eax
-	xorl	%ebx, %ebx
-	xorl	%ecx, %ecx
-	movb	$CHECKEXTENSIONSPRESENT, %ah    # Function 41
-	movw	$EDDMAGIC1, %bx			# magic
-	pushw	%dx		                # work around buggy BIOSes
-	stc					# work around buggy BIOSes
-	int	$0x13				# make the call
-	sti					# work around buggy BIOSes
-	popw	%dx
-	jc	edd_start			# no more BIOS devices
-	cmpw	$EDDMAGIC2, %bx			# is magic right?
-	jne	edd_mbr_sig_next		# nope, next...
-	testw	$FIXEDDISKSUBSET, %cx		# EXTENDED READ supported?
-	jz	edd_mbr_read_sectors		# nope, use READ SECTORS
-
-edd_mbr_extended_read:
-# Fill out the device address packet here, make the fn42 call
-	xorl	%eax, %eax
-	xorl	%ebx, %ebx
-	xorl	%ecx, %ecx
-	subw	$EDD_DEV_ADDR_PACKET_LEN, %sp	# put packet on stack
-	pushw	%si
-	movw	%sp, %si
-	movl	$0,   (%si)                      # zero out packet
-	movl	$0,  4(%si)
-	movl	$0,  8(%si)
-	movl	$0, 12(%si)
-	movb	$EDD_DEV_ADDR_PACKET_LEN, (%si) # length of packet
-	movb	$1, 2(%si)			# move 1 sector
-	movw	$EDDBUF, 4(%si)			# into EDDBUF
-	movw	%ds, 6(%si)			# EDDBUF seg is ds
-	movb	$EXTENDEDREAD, %ah
-	pushw	%dx		                # work around buggy BIOSes
-	stc					# work around buggy BIOSes
-	int	$0x13
-	sti					# work around buggy BIOSes
-	popw	%dx
-	popw	%si
-	addw	$EDD_DEV_ADDR_PACKET_LEN, %sp	# remove packet from stack
-	jnc   edd_mbr_store_sig
-	# otherwise, fall through to the legacy read function
-
-edd_mbr_read_sectors:
-# Read the first sector of each BIOS disk device and store the 4-byte signature
-	xorl	%eax, %eax
-	xorl	%ebx, %ebx
-	xorl	%ecx, %ecx
+	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
@@ -74,31 +28,23 @@ edd_mbr_read_sectors:
 	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
+    	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
+	sti                     # work around buggy BIOSes
 	popw	%dx
 	popw	%es
+	popw	%bx
 	jc	edd_mbr_sig_done		# on failure, we're done.
-
-edd_mbr_store_sig:
-	xorl	%ebx, %ebx			# clear ebx
-	movb	%dl, %bl			# copy drive number to ebx
-	sub	$0x80, %bl			# subtract 80h from drive number
-	shlw	$2, %bx				# multiply by 4
-	addw	$EDD_MBR_SIG_BUF, %bx		# add to sig_buf
-						# bx now points to the right sig slot
 	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
-edd_mbr_sig_next:
 	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_check_ext		# keep looping
+	jb	edd_mbr_sig_read		# keep looping
 edd_mbr_sig_done:
-#endif
 
 # Do the BIOS Enhanced Disk Drive calls
 # This consists of two calls:
@@ -131,35 +77,12 @@ edd_start:
 	movw	$EDDBUF+EDDEXTSIZE, %si		# in ds:si, fn41 results
 						# kept just before that
 	movb	$0, (EDDNR)			# zero value at EDDNR
-	xorl	%edx, %edx
 	movb	$0x80, %dl			# BIOS device 0x80
 
 edd_check_ext:
-	pushw	%di				# zero out this edd_info block
-	pushw	%es
-	movw	%ds, %ax
-	movw	%ax, %es
-	movw	%si, %ax
-	subw	$EDDEXTSIZE, %ax
-	movw	%ax, %di
-	movl	$EDDEXTSIZE+EDDPARMSIZE, %ecx
-	xorl	%eax, %eax
-	cld
-	rep
-	stosb
-	popw	%es
-	popw	%di
-
-	xorl	%eax, %eax
-	xorl	%ebx, %ebx
-	xorl	%ecx, %ecx
 	movb	$CHECKEXTENSIONSPRESENT, %ah    # Function 41
 	movw	$EDDMAGIC1, %bx			# magic
-	pushw	%dx		                # work around buggy BIOSes
-	stc					# work around buggy BIOSes
 	int	$0x13				# make the call
-	sti					# work around buggy BIOSes
-	popw	%dx
 	jc	edd_done			# no more BIOS devices
 
 	cmpw	$EDDMAGIC2, %bx			# is magic right?
@@ -170,38 +93,25 @@ edd_check_ext:
 	movw	%cx, %ds:-6(%si)		# store extensions
 	incb	(EDDNR)				# note that we stored something
 
-     	testw	$GET_DEVICE_PARAMETERS_SUPPORTED, %cx
-	jz	edd_get_legacy_chs	# nope, skip fn48
-
 edd_get_device_params:
-	xorl	%eax, %eax
-	xorl	%ebx, %ebx
-	xorl	%ecx, %ecx
 	movw	$EDDPARMSIZE, %ds:(%si)		# put size
+	movw	$0x0, %ds:2(%si)		# work around buggy BIOSes
 	movb	$GETDEVICEPARAMETERS, %ah	# Function 48
-	pushw	%dx		                # work around buggy BIOSes
-	stc					# work around buggy BIOSes
 	int	$0x13				# make the call
-	sti					# work around buggy BIOSes
-	popw	%dx
 						# Don't check for fail return
 						# it doesn't matter.
 edd_get_legacy_chs:
-	xorl	%eax, %eax
-	xorl	%ebx, %ebx
-	xorl	%ecx, %ecx
+	xorw    %ax, %ax
 	movw    %ax, %ds:-4(%si)
 	movw    %ax, %ds:-2(%si)
-	# Ralf Brown's Interrupt List says to set ES:DI to
+        # Ralf Brown's Interrupt List says to set ES:DI to
 	# 0000h:0000h "to guard against BIOS bugs"
-     	pushw   %es
+	pushw   %es
 	movw    %ax, %es
 	movw    %ax, %di
 	pushw   %dx                             # legacy call clobbers %dl
 	movb    $LEGACYGETDEVICEPARAMETERS, %ah # Function 08
-	stc					# work around buggy BIOSes
 	int     $0x13                           # make the call
-	sti					# work around buggy BIOSes
 	jc      edd_legacy_done                 # failed
 	movb    %cl, %al                        # Low 6 bits are max
 	andb    $0x3F, %al                      #   sector number

drivers/firmware/Kconfig

@@ -18,17 +18,6 @@ config EDD
           obscure configurations. Most disk controller BIOS vendors do
           not yet implement this feature.
 
-config EDD_SKIP_MBR
-	bool "EDD: Skip Master Boot Record read"
-	depends on EDD
-        default n
-	help
-	  Most controller BIOSs properly implement real-mode legacy
-	  READ SECTORS commands.  A few don't.
-
-	  If your controller hangs during the kernel's real-mode
-	  startup routine, say Y here.
-
 config EFI_VARS
 	tristate "EFI Variable Support via sysfs"
 	depends on EFI

include/linux/edd.h

@@ -37,18 +37,14 @@
 #define EDDEXTSIZE 8		/* change these if you muck with the structures */
 #define EDDPARMSIZE 74
 #define CHECKEXTENSIONSPRESENT 0x41
-#define EXTENDEDREAD 0x42
 #define GETDEVICEPARAMETERS 0x48
 #define LEGACYGETDEVICEPARAMETERS 0x08
 #define EDDMAGIC1 0x55AA
 #define EDDMAGIC2 0xAA55
-#define FIXEDDISKSUBSET 0x0001
-#define GET_DEVICE_PARAMETERS_SUPPORTED 0x0007
 
 
 #define READ_SECTORS 0x02         /* int13 AH=0x02 is READ_SECTORS command */
 #define EDD_MBR_SIG_OFFSET 0x1B8  /* offset of signature in the MBR */
-#define EDD_DEV_ADDR_PACKET_LEN 0x10  /* for int13 fn42 */
 #define EDD_MBR_SIG_BUF    0x290  /* addr in boot params */
 #define EDD_MBR_SIG_MAX 16        /* max number of signatures to store */
 #define EDD_MBR_SIG_NR_BUF 0x1ea  /* addr of number of MBR signtaures at EDD_MBR_SIG_BUF