Synced with following files:

  src/sys/boot/i386/Makefile.inc	1.1
  src/sys/boot/i386/btx/btx/btx.s	1.15
  src/sys/boot/i386/btx/btxldr/Makefile	1.8
  src/sys/boot/i386/btx/btxldr/btxldr.s	1.9
  src/sys/boot/i386/libi386/biosdisk.c	1.29
  src/sys/boot/i386/loader/Makefile	1.42
  src/sys/boot/i386/loader/main.c	1.18
(entry point address of loader was not changed.)

Reviewed by:	nyan

5 files changed, 246 insertions, 162 deletions

diff --git a/sys/boot/pc98/btx/btx/btx.S b/sys/boot/pc98/btx/btx/btx.S
index 5858dda..408485d 100644
--- a/sys/boot/pc98/btx/btx/btx.S
+++ b/sys/boot/pc98/btx/btx/btx.S
@@ -82,12 +82,15 @@
 # BIOS Data Area locations.
 #
 .`ifdef' PC98
-		.set BDA_MEM,0xa1501		# Free memory
-		.set BDA_POS,0xa153e		# Cursor position
+		.set BDA_MEM,0x501		# Free memory
+		.set BDA_KEYFLAGS,0x53a		# Keyboard shift-state flags
+		.set BDA_POS,0x53e		# Cursor position
 .else
 		.set BDA_MEM,0x413		# Free memory
+		.set BDA_KEYFLAGS,0x417		# Keyboard shift-state flags
 		.set BDA_SCR,0x449		# Video mode
 		.set BDA_POS,0x450		# Cursor position
+		.set BDA_BOOT,0x472		# Boot howto flag
 .endif
 #
 # Derivations, for brevity.
@@ -316,7 +319,10 @@ exit.3:		jz exit.3			# No
 		outb %al,$0xf0
 exit.4:		jmp exit.4
 .else
-		int $0x19			# BIOS: Reboot
+		.code16
+		movw $0x1234, BDA_BOOT		# Do a warm boot
+		jmpfwi(0xffff,0x0)		# reboot the machine
+		.code32
 .endif
 #
 # Set IRQ offsets by reprogramming 8259A PICs.
@@ -671,6 +677,8 @@ int15_87:	pushl %eax			# Save
 		pushl %ecx			# stash ECX
 		xorl %ecx,%ecx			# highw of ECX is clear
 		movw 0x18(%ebp),%cx		# Get user's ECX
+		shll $0x1,%ecx			# Convert from num words to num
+						#  bytes
 		rep				# repeat...
 		movsb				#  perform copy.
 		popl %ecx			# Restore
@@ -684,19 +692,40 @@ int15_87:	pushl %eax			# Save
 		jmp v86mon.5			# Finish up
 
 #
+# Reboot the machine by setting the reboot flag and exiting
+#
+reboot:		orb $0x1,btx_hdr+0x7		# Set the reboot flag
+		jmp exit			# Terminate BTX and reboot
+
+#
 # Emulate INT imm8... also make sure to check if it's int 15/87
 #
 v86intn:	lodsb				# Get int no
+		cmpb $0x19,%al			# is it int 19?
+		je reboot			#  yes, reboot the machine
 		cmpb $0x15,%al			# is it int 15?
-		jne v86intn.2			#  no, skip parse
+		jne v86intn.3			#  no, skip parse
 		pushl %eax                      # stash EAX
 		movl 0x1c(%ebp),%eax		# user's saved EAX
-		cmpb $0x87,%ah			# is it our sub function?
-		jne v86intn.1			#  no, don't handle it
+		cmpb $0x87,%ah			# is it the memcpy subfunction?
+		jne v86intn.1			#  no, keep checking
 		popl %eax			# get the stack straight
 		jmp int15_87			# it's our cue
-v86intn.1:	popl %eax			# restore EAX
-v86intn.2:	subl %edi,%esi			# From
+v86intn.1:	cmpw $0x4f53,%ax		# is it the delete key callout?
+		jne v86intn.2			#  no, handle the int normally
+		movb BDA_KEYFLAGS,%al		# get the shift key state
+.`ifdef' PC98
+		andb $0x18,%al			# mask off just Ctrl and Alt
+		cmpb $0x18,%al			# are both Ctrl and Alt down?
+.else
+		andb $0xc,%al			# mask off just Ctrl and Alt
+		cmpb $0xc,%al			# are both Ctrl and Alt down?
+.endif
+		jne v86intn.2			#  no, handle the int normally
+		popl %eax			# restore EAX
+		jmp reboot			# reboot the machine
+v86intn.2:	popl %eax			# restore EAX
+v86intn.3:	subl %edi,%esi			# From
 		shrl $0x4,%edi			#  linear
 		movw %dx,-0x2(%ebx)		# Save flags
 		movw %di,-0x4(%ebx)		# Save CS
diff --git a/sys/boot/pc98/btx/btx/btx.s b/sys/boot/pc98/btx/btx/btx.s
index 5858dda..408485d 100644
--- a/sys/boot/pc98/btx/btx/btx.s
+++ b/sys/boot/pc98/btx/btx/btx.s
@@ -82,12 +82,15 @@
 # BIOS Data Area locations.
 #
 .`ifdef' PC98
-		.set BDA_MEM,0xa1501		# Free memory
-		.set BDA_POS,0xa153e		# Cursor position
+		.set BDA_MEM,0x501		# Free memory
+		.set BDA_KEYFLAGS,0x53a		# Keyboard shift-state flags
+		.set BDA_POS,0x53e		# Cursor position
 .else
 		.set BDA_MEM,0x413		# Free memory
+		.set BDA_KEYFLAGS,0x417		# Keyboard shift-state flags
 		.set BDA_SCR,0x449		# Video mode
 		.set BDA_POS,0x450		# Cursor position
+		.set BDA_BOOT,0x472		# Boot howto flag
 .endif
 #
 # Derivations, for brevity.
@@ -316,7 +319,10 @@ exit.3:		jz exit.3			# No
 		outb %al,$0xf0
 exit.4:		jmp exit.4
 .else
-		int $0x19			# BIOS: Reboot
+		.code16
+		movw $0x1234, BDA_BOOT		# Do a warm boot
+		jmpfwi(0xffff,0x0)		# reboot the machine
+		.code32
 .endif
 #
 # Set IRQ offsets by reprogramming 8259A PICs.
@@ -671,6 +677,8 @@ int15_87:	pushl %eax			# Save
 		pushl %ecx			# stash ECX
 		xorl %ecx,%ecx			# highw of ECX is clear
 		movw 0x18(%ebp),%cx		# Get user's ECX
+		shll $0x1,%ecx			# Convert from num words to num
+						#  bytes
 		rep				# repeat...
 		movsb				#  perform copy.
 		popl %ecx			# Restore
@@ -684,19 +692,40 @@ int15_87:	pushl %eax			# Save
 		jmp v86mon.5			# Finish up
 
 #
+# Reboot the machine by setting the reboot flag and exiting
+#
+reboot:		orb $0x1,btx_hdr+0x7		# Set the reboot flag
+		jmp exit			# Terminate BTX and reboot
+
+#
 # Emulate INT imm8... also make sure to check if it's int 15/87
 #
 v86intn:	lodsb				# Get int no
+		cmpb $0x19,%al			# is it int 19?
+		je reboot			#  yes, reboot the machine
 		cmpb $0x15,%al			# is it int 15?
-		jne v86intn.2			#  no, skip parse
+		jne v86intn.3			#  no, skip parse
 		pushl %eax                      # stash EAX
 		movl 0x1c(%ebp),%eax		# user's saved EAX
-		cmpb $0x87,%ah			# is it our sub function?
-		jne v86intn.1			#  no, don't handle it
+		cmpb $0x87,%ah			# is it the memcpy subfunction?
+		jne v86intn.1			#  no, keep checking
 		popl %eax			# get the stack straight
 		jmp int15_87			# it's our cue
-v86intn.1:	popl %eax			# restore EAX
-v86intn.2:	subl %edi,%esi			# From
+v86intn.1:	cmpw $0x4f53,%ax		# is it the delete key callout?
+		jne v86intn.2			#  no, handle the int normally
+		movb BDA_KEYFLAGS,%al		# get the shift key state
+.`ifdef' PC98
+		andb $0x18,%al			# mask off just Ctrl and Alt
+		cmpb $0x18,%al			# are both Ctrl and Alt down?
+.else
+		andb $0xc,%al			# mask off just Ctrl and Alt
+		cmpb $0xc,%al			# are both Ctrl and Alt down?
+.endif
+		jne v86intn.2			#  no, handle the int normally
+		popl %eax			# restore EAX
+		jmp reboot			# reboot the machine
+v86intn.2:	popl %eax			# restore EAX
+v86intn.3:	subl %edi,%esi			# From
 		shrl $0x4,%edi			#  linear
 		movw %dx,-0x2(%ebx)		# Save flags
 		movw %di,-0x4(%ebx)		# Save CS
diff --git a/sys/boot/pc98/btx/btxldr/Makefile b/sys/boot/pc98/btx/btxldr/Makefile
index b6f4016..35964ce 100644
--- a/sys/boot/pc98/btx/btxldr/Makefile
+++ b/sys/boot/pc98/btx/btxldr/Makefile
@@ -1,26 +1,28 @@
 # $FreeBSD$
 
-ORG=0x100000
-#AFLAGS+=	-x assembler-with-cpp
+M4?=	m4
+M4FLAGS+=	-DLOADER_ADDRESS=${LOADER_ADDRESS} -DPC98
 
-#AFLAGS+=	--defsym PC98=1 --defsym BTXLDR_VERBOSE=1
-AFLAGS+=	--defsym PC98=1
+.if defined(BTXLDR_VERBOSE)
+M4FLAGS+=	-DBTXLDR_VERBOSE
+.endif
 
 all: btxldr
 
 btxldr: btxldr.o
 .if ${OBJFORMAT} == aout
-	${LD} -nostdlib -N -s -T ${ORG} -o btxldr.out btxldr.o
+	${LD} -nostdlib -N -s -T ${LOADER_ADDRESS} -o btxldr.out btxldr.o
 	dd if=btxldr.out of=${.TARGET} ibs=32 skip=1
 .else
-	${LD} -N -e start -Ttext ${ORG} -o btxldr.out btxldr.o
+	${LD} -N -e start -Ttext ${LOADER_ADDRESS} -o btxldr.out btxldr.o
 	objcopy -S -O binary btxldr.out ${.TARGET}
 .endif
 
 btxldr.o: btxldr.s
-#	${CC} ${AFLAGS} -c -o ${.TARGET} ${.CURDIR}/btxldr.s
-	${AS} ${AFLAGS} -o ${.TARGET} ${.CURDIR}/btxldr.s
+	(cd ${.CURDIR}; ${M4} ${M4FLAGS} btxldr.s ) | \
+		${AS} ${AFLAGS} -o ${.TARGET}
 
 CLEANFILES+= btxldr btxldr.out btxldr.o
 
+.include <${.CURDIR}/../../Makefile.inc>
 .include <bsd.prog.mk>
diff --git a/sys/boot/pc98/btx/btxldr/btxldr.S b/sys/boot/pc98/btx/btxldr/btxldr.S
index acb4a14..74b8a6d 100644
--- a/sys/boot/pc98/btx/btxldr/btxldr.S
+++ b/sys/boot/pc98/btx/btxldr/btxldr.S
@@ -27,7 +27,7 @@
 		.set MEM_ESP,0x1000		# New stack pointer
 		.set MEM_TBL,0x5000		# BTX page tables
 		.set MEM_ENTRY,0x9010		# BTX entry point
-		.set MEM_DATA,0x101000		# Data segment
+		.set MEM_DATA,start+0x1000	# Data segment
 #
 # Segment selectors.
 #
@@ -43,37 +43,37 @@
 #
 # Screen constants.
 #
-.ifdef PC98
+ifdef(`PC98',`
 		.set SCR_MAT,0xe1		# Mode/attribute
-.else
+',`
 		.set SCR_MAT,0x7		# Mode/attribute
-.endif
+')
 		.set SCR_COL,0x50		# Columns per row
 		.set SCR_ROW,0x19		# Rows per screen
 #
 # BIOS Data Area locations.
 #
-.ifdef PC98
+ifdef(`PC98',`
 		.set BDA_MEM,0xa1501		# Free memory
 		.set BDA_POS,0xa153e		# Cursor position
-.else
+',`
 		.set BDA_MEM,0x413		# Free memory
 		.set BDA_SCR,0x449		# Video mode
 		.set BDA_POS,0x450		# Cursor position
-.endif
+')
 #
 # Required by aout gas inadequacy.
 #
 		.set SIZ_STUB,0x1a		# Size of stub
 #
-# We expect to be loaded by boot2 at 0x100000.
+# We expect to be loaded by boot2 at the origin defined in ./Makefile.
 #
 		.globl start
 #
 # BTX program loader for ELF clients.
 #
 start:		cld				# String ops inc
-.ifdef PC98
+ifdef(`PC98',`
 		cli
 gdcwait.1:	inb $0x60,%al
 		testb $0x04,%al
@@ -94,58 +94,68 @@ gdcwait.2:	inb $0x60,%al
 		shlw $1,%dx
 		movl $BDA_POS,%ebx
 		movw %dx,(%ebx)
-.endif
+')
 		movl $m_logo,%esi		# Identify
 		call putstr			#  ourselves
 		movzwl BDA_MEM,%eax		# Get base memory
-.ifdef PC98
+ifdef(`PC98',`
 		andl $0x7,%eax
 		incl %eax
 		shll $0x11,%eax			#  in bytes
-.else
+',`
 		shll $0xa,%eax			#  in bytes
-.endif
+')
 		movl %eax,%ebp			# Base of user stack
+ifdef(`BTXLDR_VERBOSE',`
 		movl $m_mem,%esi		# Display
-		call dhexout			#  amount of
-		call dputstr			#  base memory
+		call hexout			#  amount of
+		call putstr			#  base memory
+')
 		lgdt gdtdesc			# Load new GDT
 #
 # Relocate caller's arguments.
 #
+ifdef('BTXLDR_VERBOSE',`
 		movl $m_esp,%esi		# Display
-		movl %esp,%eax			#  caller's
-		call dhexout			#  stack
-		call dputstr			#  pointer
+		movl %esp,%eax			#  caller
+		call hexout			#  stack
+		call putstr			#  pointer
 		movl $m_args,%esi		# Format string
 		leal 0x4(%esp,1),%ebx		# First argument
 		movl $0x6,%ecx			# Count
 start.1:	movl (%ebx),%eax		# Get argument and
 		addl $0x4,%ebx			#  bump pointer
-		call dhexout			# Display it
+		call hexout			# Display it
 		loop start.1			# Till done
-		call dputstr			# End message
+		call putstr			# End message
+')
 		movl $0x48,%ecx 		# Allocate space
 		subl %ecx,%ebp			#  for bootinfo
-		movl 0x18(%esp,1),%esi		# Source
+		movl 0x18(%esp,1),%esi		# Source: bootinfo
+		cmpl $0x0, %esi			# If the bootinfo pointer
+		je start_null_bi		#  is null, don't copy it
 		movl %ebp,%edi			# Destination
 		rep				# Copy
 		movsb				#  it
 		movl %ebp,0x18(%esp,1)		# Update pointer
+ifdef(`BTXLDR_VERBOSE',`
 		movl $m_rel_bi,%esi		# Display
 		movl %ebp,%eax			#  bootinfo
-		call dhexout			#  relocation
-		call dputstr			#  message
-		movl $0x18,%ecx 		# Allocate space
+		call hexout			#  relocation
+		call putstr			#  message
+')
+start_null_bi:	movl $0x18,%ecx 		# Allocate space
 		subl %ecx,%ebp			#  for arguments
 		leal 0x4(%esp,1),%esi		# Source
 		movl %ebp,%edi			# Destination
 		rep				# Copy
 		movsb				#  them
+ifdef(`BTXLDR_VERBOSE',`
 		movl $m_rel_args,%esi		# Display
 		movl %ebp,%eax			#  argument
-		call dhexout			#  relocation
-		call dputstr			#  message
+		call hexout			#  relocation
+		call putstr			#  message
+')
 #
 # Set up BTX kernel.
 #
@@ -174,24 +184,32 @@ start.1:	movl (%ebx),%eax		# Get argument and
 		incl %edi			#  BTX
 		shll $0x2,%edi			#  load
 		addl $MEM_TBL,%edi		#  address
-		pushl %edi			# Save
+		pushl %edi			# Save load address
 		movzwl 0xa(%ebx),%ecx		# Image size
-		pushl %ecx			# Save
+ifdef(`BTXLDR_VERBOSE',`
+		pushl %ecx			# Save image size
+')
 		rep				# Relocate
 		movsb				#  BTX
 		movl %esi,%ebx			# Keep place
+ifdef(`BTXLDR_VERBOSE',`
 		movl $m_rel_btx,%esi		# Restore
 		popl %eax			#  parameters
-		call dhexout			#  and
+		call hexout			#  and
+')
 		popl %ebp			#  display
+ifdef(`BTXLDR_VERBOSE',`
 		movl %ebp,%eax			#  the
-		call dhexout			#  relocation
-		call dputstr			#  message
+		call hexout			#  relocation
+		call putstr			#  message
+')
 		addl $PAG_SIZ,%ebp		# Display
+ifdef(`BTXLDR_VERBOSE',`
 		movl $m_base,%esi		#  the
 		movl %ebp,%eax			#  user
-		call dhexout			#  base
-		call dputstr			#  address
+		call hexout			#  base
+		call putstr			#  address
+')
 #
 # Set up ELF-format client program.
 #
@@ -200,24 +218,29 @@ start.1:	movl (%ebx),%eax		# Get argument and
 		movl $e_fmt,%esi		# Display error
 		call putstr			#  message
 start.2:	jmp start.2			# Hang
-start.3:	movl $m_elf,%esi		# Display ELF
-		call dputstr			#  message
+start.3:
+ifdef(`BTXLDR_VERBOSE',`
+		movl $m_elf,%esi		# Display ELF
+		call putstr			#  message
 		movl $m_segs,%esi		# Format string
+')
 		movl $0x2,%edi			# Segment count
 		movl 0x1c(%ebx),%edx		# Get e_phoff
 		addl %ebx,%edx			# To pointer
 		movzwl 0x2c(%ebx),%ecx		# Get e_phnum
 start.4:	cmpl $0x1,(%edx)		# Is p_type PT_LOAD?
 		jne start.6			# No
+ifdef(`BTXLDR_VERBOSE',`
 		movl 0x4(%edx),%eax		# Display
-		call dhexout			#  p_offset
+		call hexout			#  p_offset
 		movl 0x8(%edx),%eax		# Display
-		call dhexout			#  p_vaddr
+		call hexout			#  p_vaddr
 		movl 0x10(%edx),%eax		# Display
-		call dhexout			#  p_filesz
+		call hexout			#  p_filesz
 		movl 0x14(%edx),%eax		# Display
-		call dhexout			#  p_memsz
-		call dputstr			# End message
+		call hexout			#  p_memsz
+		call putstr			# End message
+')
 		pushl %esi			# Save
 		pushl %edi			#  working
 		pushl %ecx			#  registers
@@ -241,8 +264,11 @@ start.5:	popl %ecx			# Restore
 		je start.7			# If none
 start.6:	addl $0x20,%edx 		# To next entry
 		loop start.4			# Till done
-start.7:	movl $m_done,%esi		# Display done
-		call dputstr			#  message
+start.7:
+ifdef(`BTXLDR_VERBOSE',`
+		movl $m_done,%esi		# Display done
+		call putstr			#  message
+')
 		movl $start.8,%esi		# Real mode stub
 		movl $MEM_STUB,%edi		# Destination
 		movl $SIZ_STUB,%ecx		# Size
@@ -266,10 +292,6 @@ start.9:
 #
 # Output message [ESI] followed by EAX in hex.
 #
-dhexout:
-.ifndef BTXLDR_VERBOSE
-		ret
-.endif
 hexout: 	pushl %eax			# Save
 		call putstr			# Display message
 		popl %eax			# Restore
@@ -295,12 +317,6 @@ hexout.2:	decl %esi			# Adjust for inc
 #
 # Output zero-terminated string [ESI] to the console.
 #
-dputstr:
-.ifndef BTXLDR_VERBOSE
-		ret
-.else
-		jmp putstr
-.endif
 putstr.0:	call putchr			# Output char
 putstr: 	lodsb				# Load char
 		testb %al,%al			# End of string?
@@ -309,26 +325,22 @@ putstr: 	lodsb				# Load char
 #
 # Output character AL to the console.
 #
-dputchr:
-.ifndef BTXLDR_VERBOSE
-		ret
-.endif
 putchr: 	pusha				# Save
 		xorl %ecx,%ecx			# Zero for loops
 		movb $SCR_MAT,%ah		# Mode/attribute
 		movl $BDA_POS,%ebx		# BDA pointer
 		movw (%ebx),%dx 		# Cursor position
-.ifdef PC98
+ifdef(`PC98',`
 		movl $0xa0000,%edi		# Regen buffer (color)
-.else
+',`
 		movl $0xb8000,%edi		# Regen buffer (color)
 		cmpb %ah,BDA_SCR-BDA_POS(%ebx)	# Mono mode?
 		jne putchr.1			# No
 		xorw %di,%di			# Regen buffer (mono)
-.endif
+')
 putchr.1:	cmpb $0xa,%al			# New line?
 		je putchr.2			# Yes
-.ifdef PC98
+ifdef(`PC98',`
 		movw %dx,%cx
 		movb %al,(%edi,%ecx,1)		# Write char
 		addl $0x2000,%ecx
@@ -342,7 +354,7 @@ putchr.2:	movw %dx,%ax
 		mul %dl
 		movw %ax,%dx
 putchr.3:	cmpw $SCR_COL*SCR_ROW*2,%dx
-.else
+',`
 		xchgl %eax,%ecx 		# Save char
 		movb $SCR_COL,%al		# Columns per row
 		mulb %dh			#  * row position
@@ -357,20 +369,20 @@ putchr.3:	cmpw $SCR_COL*SCR_ROW*2,%dx
 putchr.2:	xorb %dl,%dl			# Zero column
 		incb %dh			# Bump row
 putchr.3:	cmpb $SCR_ROW,%dh		# Beyond screen?
-.endif
+')
 		jb putchr.4			# No
 		leal 2*SCR_COL(%edi),%esi	# New top line
 		movw $(SCR_ROW-1)*SCR_COL/2,%cx # Words to move
 		rep				# Scroll
 		movsl				#  screen
 		movb $' ',%al			# Space
-.ifdef PC98
+ifdef(`PC98',`
 		xorb %ah,%ah
-.endif
+')
 		movb $SCR_COL,%cl		# Columns to clear
 		rep				# Clear
 		stosw				#  line
-.ifdef PC98
+ifdef(`PC98',`
 		movw $(SCR_ROW-1)*SCR_COL*2,%dx
 putchr.4:	movw %dx,(%ebx) 		# Update position
 		shrw $1,%dx
@@ -383,10 +395,10 @@ gdcwait.3:	inb $0x60,%al
 		outb %al,$0x60
 		movb %dh,%al
 		outb %al,$0x60
-.else
+',`
 		movb $SCR_ROW-1,%dh		# Bottom line
 putchr.4:	movw %dx,(%ebx) 		# Update position
-.endif
+')
 		popa				# Restore
 		ret				# To caller
 #
@@ -429,7 +441,7 @@ gdtdesc:	.word gdt.1-gdt-1		# Limit
 m_logo: 	.asciz " \nBTX loader 1.00  "
 m_vers: 	.asciz "BTX version is \0\n"
 e_fmt:		.asciz "Error: Client format not supported\n"
-#.ifdef BTXLDR_VERBOSE
+ifdef(`BTXLDR_VERBOSE',`
 m_mem:		.asciz "Starting in protected mode (base mem=\0)\n"
 m_esp:		.asciz "Arguments passed (esp=\0):\n"
 m_args: 	.asciz"<howto="
@@ -452,7 +464,7 @@ m_segs: 	.asciz "text segment: offset="
 		.asciz " filesz="
 		.asciz " memsz=\0\n"
 m_done: 	.asciz "Loading complete\n"
-#.endif
+')
 #
 # Uninitialized data area.
 #
diff --git a/sys/boot/pc98/btx/btxldr/btxldr.s b/sys/boot/pc98/btx/btxldr/btxldr.s
index acb4a14..74b8a6d 100644
--- a/sys/boot/pc98/btx/btxldr/btxldr.s
+++ b/sys/boot/pc98/btx/btxldr/btxldr.s
@@ -27,7 +27,7 @@
 		.set MEM_ESP,0x1000		# New stack pointer
 		.set MEM_TBL,0x5000		# BTX page tables
 		.set MEM_ENTRY,0x9010		# BTX entry point
-		.set MEM_DATA,0x101000		# Data segment
+		.set MEM_DATA,start+0x1000	# Data segment
 #
 # Segment selectors.
 #
@@ -43,37 +43,37 @@
 #
 # Screen constants.
 #
-.ifdef PC98
+ifdef(`PC98',`
 		.set SCR_MAT,0xe1		# Mode/attribute
-.else
+',`
 		.set SCR_MAT,0x7		# Mode/attribute
-.endif
+')
 		.set SCR_COL,0x50		# Columns per row
 		.set SCR_ROW,0x19		# Rows per screen
 #
 # BIOS Data Area locations.
 #
-.ifdef PC98
+ifdef(`PC98',`
 		.set BDA_MEM,0xa1501		# Free memory
 		.set BDA_POS,0xa153e		# Cursor position
-.else
+',`
 		.set BDA_MEM,0x413		# Free memory
 		.set BDA_SCR,0x449		# Video mode
 		.set BDA_POS,0x450		# Cursor position
-.endif
+')
 #
 # Required by aout gas inadequacy.
 #
 		.set SIZ_STUB,0x1a		# Size of stub
 #
-# We expect to be loaded by boot2 at 0x100000.
+# We expect to be loaded by boot2 at the origin defined in ./Makefile.
 #
 		.globl start
 #
 # BTX program loader for ELF clients.
 #
 start:		cld				# String ops inc
-.ifdef PC98
+ifdef(`PC98',`
 		cli
 gdcwait.1:	inb $0x60,%al
 		testb $0x04,%al
@@ -94,58 +94,68 @@ gdcwait.2:	inb $0x60,%al
 		shlw $1,%dx
 		movl $BDA_POS,%ebx
 		movw %dx,(%ebx)
-.endif
+')
 		movl $m_logo,%esi		# Identify
 		call putstr			#  ourselves
 		movzwl BDA_MEM,%eax		# Get base memory
-.ifdef PC98
+ifdef(`PC98',`
 		andl $0x7,%eax
 		incl %eax
 		shll $0x11,%eax			#  in bytes
-.else
+',`
 		shll $0xa,%eax			#  in bytes
-.endif
+')
 		movl %eax,%ebp			# Base of user stack
+ifdef(`BTXLDR_VERBOSE',`
 		movl $m_mem,%esi		# Display
-		call dhexout			#  amount of
-		call dputstr			#  base memory
+		call hexout			#  amount of
+		call putstr			#  base memory
+')
 		lgdt gdtdesc			# Load new GDT
 #
 # Relocate caller's arguments.
 #
+ifdef('BTXLDR_VERBOSE',`
 		movl $m_esp,%esi		# Display
-		movl %esp,%eax			#  caller's
-		call dhexout			#  stack
-		call dputstr			#  pointer
+		movl %esp,%eax			#  caller
+		call hexout			#  stack
+		call putstr			#  pointer
 		movl $m_args,%esi		# Format string
 		leal 0x4(%esp,1),%ebx		# First argument
 		movl $0x6,%ecx			# Count
 start.1:	movl (%ebx),%eax		# Get argument and
 		addl $0x4,%ebx			#  bump pointer
-		call dhexout			# Display it
+		call hexout			# Display it
 		loop start.1			# Till done
-		call dputstr			# End message
+		call putstr			# End message
+')
 		movl $0x48,%ecx 		# Allocate space
 		subl %ecx,%ebp			#  for bootinfo
-		movl 0x18(%esp,1),%esi		# Source
+		movl 0x18(%esp,1),%esi		# Source: bootinfo
+		cmpl $0x0, %esi			# If the bootinfo pointer
+		je start_null_bi		#  is null, don't copy it
 		movl %ebp,%edi			# Destination
 		rep				# Copy
 		movsb				#  it
 		movl %ebp,0x18(%esp,1)		# Update pointer
+ifdef(`BTXLDR_VERBOSE',`
 		movl $m_rel_bi,%esi		# Display
 		movl %ebp,%eax			#  bootinfo
-		call dhexout			#  relocation
-		call dputstr			#  message
-		movl $0x18,%ecx 		# Allocate space
+		call hexout			#  relocation
+		call putstr			#  message
+')
+start_null_bi:	movl $0x18,%ecx 		# Allocate space
 		subl %ecx,%ebp			#  for arguments
 		leal 0x4(%esp,1),%esi		# Source
 		movl %ebp,%edi			# Destination
 		rep				# Copy
 		movsb				#  them
+ifdef(`BTXLDR_VERBOSE',`
 		movl $m_rel_args,%esi		# Display
 		movl %ebp,%eax			#  argument
-		call dhexout			#  relocation
-		call dputstr			#  message
+		call hexout			#  relocation
+		call putstr			#  message
+')
 #
 # Set up BTX kernel.
 #
@@ -174,24 +184,32 @@ start.1:	movl (%ebx),%eax		# Get argument and
 		incl %edi			#  BTX
 		shll $0x2,%edi			#  load
 		addl $MEM_TBL,%edi		#  address
-		pushl %edi			# Save
+		pushl %edi			# Save load address
 		movzwl 0xa(%ebx),%ecx		# Image size
-		pushl %ecx			# Save
+ifdef(`BTXLDR_VERBOSE',`
+		pushl %ecx			# Save image size
+')
 		rep				# Relocate
 		movsb				#  BTX
 		movl %esi,%ebx			# Keep place
+ifdef(`BTXLDR_VERBOSE',`
 		movl $m_rel_btx,%esi		# Restore
 		popl %eax			#  parameters
-		call dhexout			#  and
+		call hexout			#  and
+')
 		popl %ebp			#  display
+ifdef(`BTXLDR_VERBOSE',`
 		movl %ebp,%eax			#  the
-		call dhexout			#  relocation
-		call dputstr			#  message
+		call hexout			#  relocation
+		call putstr			#  message
+')
 		addl $PAG_SIZ,%ebp		# Display
+ifdef(`BTXLDR_VERBOSE',`
 		movl $m_base,%esi		#  the
 		movl %ebp,%eax			#  user
-		call dhexout			#  base
-		call dputstr			#  address
+		call hexout			#  base
+		call putstr			#  address
+')
 #
 # Set up ELF-format client program.
 #
@@ -200,24 +218,29 @@ start.1:	movl (%ebx),%eax		# Get argument and
 		movl $e_fmt,%esi		# Display error
 		call putstr			#  message
 start.2:	jmp start.2			# Hang
-start.3:	movl $m_elf,%esi		# Display ELF
-		call dputstr			#  message
+start.3:
+ifdef(`BTXLDR_VERBOSE',`
+		movl $m_elf,%esi		# Display ELF
+		call putstr			#  message
 		movl $m_segs,%esi		# Format string
+')
 		movl $0x2,%edi			# Segment count
 		movl 0x1c(%ebx),%edx		# Get e_phoff
 		addl %ebx,%edx			# To pointer
 		movzwl 0x2c(%ebx),%ecx		# Get e_phnum
 start.4:	cmpl $0x1,(%edx)		# Is p_type PT_LOAD?
 		jne start.6			# No
+ifdef(`BTXLDR_VERBOSE',`
 		movl 0x4(%edx),%eax		# Display
-		call dhexout			#  p_offset
+		call hexout			#  p_offset
 		movl 0x8(%edx),%eax		# Display
-		call dhexout			#  p_vaddr
+		call hexout			#  p_vaddr
 		movl 0x10(%edx),%eax		# Display
-		call dhexout			#  p_filesz
+		call hexout			#  p_filesz
 		movl 0x14(%edx),%eax		# Display
-		call dhexout			#  p_memsz
-		call dputstr			# End message
+		call hexout			#  p_memsz
+		call putstr			# End message
+')
 		pushl %esi			# Save
 		pushl %edi			#  working
 		pushl %ecx			#  registers
@@ -241,8 +264,11 @@ start.5:	popl %ecx			# Restore
 		je start.7			# If none
 start.6:	addl $0x20,%edx 		# To next entry
 		loop start.4			# Till done
-start.7:	movl $m_done,%esi		# Display done
-		call dputstr			#  message
+start.7:
+ifdef(`BTXLDR_VERBOSE',`
+		movl $m_done,%esi		# Display done
+		call putstr			#  message
+')
 		movl $start.8,%esi		# Real mode stub
 		movl $MEM_STUB,%edi		# Destination
 		movl $SIZ_STUB,%ecx		# Size
@@ -266,10 +292,6 @@ start.9:
 #
 # Output message [ESI] followed by EAX in hex.
 #
-dhexout:
-.ifndef BTXLDR_VERBOSE
-		ret
-.endif
 hexout: 	pushl %eax			# Save
 		call putstr			# Display message
 		popl %eax			# Restore
@@ -295,12 +317,6 @@ hexout.2:	decl %esi			# Adjust for inc
 #
 # Output zero-terminated string [ESI] to the console.
 #
-dputstr:
-.ifndef BTXLDR_VERBOSE
-		ret
-.else
-		jmp putstr
-.endif
 putstr.0:	call putchr			# Output char
 putstr: 	lodsb				# Load char
 		testb %al,%al			# End of string?
@@ -309,26 +325,22 @@ putstr: 	lodsb				# Load char
 #
 # Output character AL to the console.
 #
-dputchr:
-.ifndef BTXLDR_VERBOSE
-		ret
-.endif
 putchr: 	pusha				# Save
 		xorl %ecx,%ecx			# Zero for loops
 		movb $SCR_MAT,%ah		# Mode/attribute
 		movl $BDA_POS,%ebx		# BDA pointer
 		movw (%ebx),%dx 		# Cursor position
-.ifdef PC98
+ifdef(`PC98',`
 		movl $0xa0000,%edi		# Regen buffer (color)
-.else
+',`
 		movl $0xb8000,%edi		# Regen buffer (color)
 		cmpb %ah,BDA_SCR-BDA_POS(%ebx)	# Mono mode?
 		jne putchr.1			# No
 		xorw %di,%di			# Regen buffer (mono)
-.endif
+')
 putchr.1:	cmpb $0xa,%al			# New line?
 		je putchr.2			# Yes
-.ifdef PC98
+ifdef(`PC98',`
 		movw %dx,%cx
 		movb %al,(%edi,%ecx,1)		# Write char
 		addl $0x2000,%ecx
@@ -342,7 +354,7 @@ putchr.2:	movw %dx,%ax
 		mul %dl
 		movw %ax,%dx
 putchr.3:	cmpw $SCR_COL*SCR_ROW*2,%dx
-.else
+',`
 		xchgl %eax,%ecx 		# Save char
 		movb $SCR_COL,%al		# Columns per row
 		mulb %dh			#  * row position
@@ -357,20 +369,20 @@ putchr.3:	cmpw $SCR_COL*SCR_ROW*2,%dx
 putchr.2:	xorb %dl,%dl			# Zero column
 		incb %dh			# Bump row
 putchr.3:	cmpb $SCR_ROW,%dh		# Beyond screen?
-.endif
+')
 		jb putchr.4			# No
 		leal 2*SCR_COL(%edi),%esi	# New top line
 		movw $(SCR_ROW-1)*SCR_COL/2,%cx # Words to move
 		rep				# Scroll
 		movsl				#  screen
 		movb $' ',%al			# Space
-.ifdef PC98
+ifdef(`PC98',`
 		xorb %ah,%ah
-.endif
+')
 		movb $SCR_COL,%cl		# Columns to clear
 		rep				# Clear
 		stosw				#  line
-.ifdef PC98
+ifdef(`PC98',`
 		movw $(SCR_ROW-1)*SCR_COL*2,%dx
 putchr.4:	movw %dx,(%ebx) 		# Update position
 		shrw $1,%dx
@@ -383,10 +395,10 @@ gdcwait.3:	inb $0x60,%al
 		outb %al,$0x60
 		movb %dh,%al
 		outb %al,$0x60
-.else
+',`
 		movb $SCR_ROW-1,%dh		# Bottom line
 putchr.4:	movw %dx,(%ebx) 		# Update position
-.endif
+')
 		popa				# Restore
 		ret				# To caller
 #
@@ -429,7 +441,7 @@ gdtdesc:	.word gdt.1-gdt-1		# Limit
 m_logo: 	.asciz " \nBTX loader 1.00  "
 m_vers: 	.asciz "BTX version is \0\n"
 e_fmt:		.asciz "Error: Client format not supported\n"
-#.ifdef BTXLDR_VERBOSE
+ifdef(`BTXLDR_VERBOSE',`
 m_mem:		.asciz "Starting in protected mode (base mem=\0)\n"
 m_esp:		.asciz "Arguments passed (esp=\0):\n"
 m_args: 	.asciz"<howto="
@@ -452,7 +464,7 @@ m_segs: 	.asciz "text segment: offset="
 		.asciz " filesz="
 		.asciz " memsz=\0\n"
 m_done: 	.asciz "Loading complete\n"
-#.endif
+')
 #
 # Uninitialized data area.
 #