Change the comment character from # to // in boot1.s and run

it through CPP so we can conditionalized things.

Sponsored by:	DARPA & NAI Labs

4 files changed, 648 insertions, 646 deletions

diff --git a/sys/boot/i386/boot2/Makefile b/sys/boot/i386/boot2/Makefile
index e4ab3f5..4526d15 100644
--- a/sys/boot/i386/boot2/Makefile
+++ b/sys/boot/i386/boot2/Makefile
@@ -49,7 +49,8 @@ boot1.out: boot1.o
 	${LD} ${LDFLAGS} -e start -Ttext ${ORG1} -o ${.TARGET} boot1.o
 
 boot1.o: boot1.s
-	${AS} ${AFLAGS} --defsym FLAGS=${B1FLAGS} ${.IMPSRC} -o ${.TARGET}
+	${CPP} ${CFLAGS} ${.IMPSRC} | \
+	    ${AS} ${AFLAGS} --defsym FLAGS=${B1FLAGS} -o ${.TARGET}
 
 boot2.o: boot2.c ${.CURDIR}/../../common/ufsread.c
 	${CC} ${CFLAGS} -S -o boot2.s.tmp ${.IMPSRC}
diff --git a/sys/boot/i386/boot2/boot1.S b/sys/boot/i386/boot2/boot1.S
index 50a6d01..29f9560 100644
--- a/sys/boot/i386/boot2/boot1.S
+++ b/sys/boot/i386/boot2/boot1.S
@@ -1,360 +1,360 @@
-#
-# Copyright (c) 1998 Robert Nordier
-# All rights reserved.
-#
-# Redistribution and use in source and binary forms are freely
-# permitted provided that the above copyright notice and this
-# paragraph and the following disclaimer are duplicated in all
-# such forms.
-#
-# This software is provided "AS IS" and without any express or
-# implied warranties, including, without limitation, the implied
-# warranties of merchantability and fitness for a particular
-# purpose.
-#
+//
+// Copyright (c) 1998 Robert Nordier
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms are freely
+// permitted provided that the above copyright notice and this
+// paragraph and the following disclaimer are duplicated in all
+// such forms.
+//
+// This software is provided "AS IS" and without any express or
+// implied warranties, including, without limitation, the implied
+// warranties of merchantability and fitness for a particular
+// purpose.
+//
 
-# $FreeBSD$
+// $FreeBSD$
 
-# Memory Locations
-		.set MEM_REL,0x700		# Relocation address
-		.set MEM_ARG,0x900		# Arguments
-		.set MEM_ORG,0x7c00		# Origin
-		.set MEM_BUF,0x8c00		# Load area
-		.set MEM_BTX,0x9000		# BTX start
-		.set MEM_JMP,0x9010		# BTX entry point
-		.set MEM_USR,0xb000		# Client start
-		.set BDA_BOOT,0x472		# Boot howto flag
+// Memory Locations
+		.set MEM_REL,0x700		// Relocation address
+		.set MEM_ARG,0x900		// Arguments
+		.set MEM_ORG,0x7c00		// Origin
+		.set MEM_BUF,0x8c00		// Load area
+		.set MEM_BTX,0x9000		// BTX start
+		.set MEM_JMP,0x9010		// BTX entry point
+		.set MEM_USR,0xb000		// Client start
+		.set BDA_BOOT,0x472		// Boot howto flag
 	
-# Partition Constants 
-		.set PRT_OFF,0x1be		# Partition offset
-		.set PRT_NUM,0x4		# Partitions
-		.set PRT_BSD,0xa5		# Partition type
+// Partition Constants 
+		.set PRT_OFF,0x1be		// Partition offset
+		.set PRT_NUM,0x4		// Partitions
+		.set PRT_BSD,0xa5		// Partition type
 
-# Flag Bits
-		.set FL_PACKET,0x80		# Packet mode
+// Flag Bits
+		.set FL_PACKET,0x80		// Packet mode
 
-# Misc. Constants
-		.set SIZ_PAG,0x1000		# Page size
-		.set SIZ_SEC,0x200		# Sector size
+// Misc. Constants
+		.set SIZ_PAG,0x1000		// Page size
+		.set SIZ_SEC,0x200		// Sector size
 
 		.globl start
 		.globl xread
 		.code16
 
-start:		jmp main			# Start recognizably
+start:		jmp main			// Start recognizably
 
-# This is the start of a standard BIOS Parameter Block (BPB). Most bootable
-# FAT disks have this at the start of their MBR. While normal BIOS's will
-# work fine without this section, IBM's El Torito emulation "fixes" up the
-# BPB by writing into the memory copy of the MBR. Rather than have data
-# written into our xread routine, we'll define a BPB to work around it.
-# The data marked with (T) indicates a field required for a ThinkPad to
-# recognize the disk and (W) indicates fields written from IBM BIOS code.
-# The use of the BPB is based on what OpenBSD and NetBSD implemented in
-# their boot code but the required fields were determined by trial and error.
-#
-# Note: If additional space is needed in boot1, one solution would be to
-# move the "prompt" message data (below) to replace the OEM ID.
+// This is the start of a standard BIOS Parameter Block (BPB). Most bootable
+// FAT disks have this at the start of their MBR. While normal BIOS's will
+// work fine without this section, IBM's El Torito emulation "fixes" up the
+// BPB by writing into the memory copy of the MBR. Rather than have data
+// written into our xread routine, we'll define a BPB to work around it.
+// The data marked with (T) indicates a field required for a ThinkPad to
+// recognize the disk and (W) indicates fields written from IBM BIOS code.
+// The use of the BPB is based on what OpenBSD and NetBSD implemented in
+// their boot code but the required fields were determined by trial and error.
+//
+// Note: If additional space is needed in boot1, one solution would be to
+// move the "prompt" message data (below) to replace the OEM ID.
 
 		.org 0x03, 0x00
-oemid:		.space 0x08, 0x00	# OEM ID
+oemid:		.space 0x08, 0x00	// OEM ID
 
 		.org 0x0b, 0x00
-bpb:		.word   512		# sector size (T)
-		.byte	0		# sectors/clustor
-		.word	0		# reserved sectors
-		.byte	0		# number of FATs
-		.word	0		# root entries
-		.word	0		# small sectors
-		.byte	0		# media type (W)
-		.word	0		# sectors/fat
-		.word	18		# sectors per track (T)
-		.word	2		# number of heads (T)
-		.long	0		# hidden sectors (W)
-		.long	0		# large sectors
+bpb:		.word   512		// sector size (T)
+		.byte	0		// sectors/clustor
+		.word	0		// reserved sectors
+		.byte	0		// number of FATs
+		.word	0		// root entries
+		.word	0		// small sectors
+		.byte	0		// media type (W)
+		.word	0		// sectors/fat
+		.word	18		// sectors per track (T)
+		.word	2		// number of heads (T)
+		.long	0		// hidden sectors (W)
+		.long	0		// large sectors
 
 		.org 0x24, 0x00
-ebpb:		.byte	0		# BIOS physical drive number (W)
+ebpb:		.byte	0		// BIOS physical drive number (W)
 
 		.org 0x25,0x90
-# 
-# Trampoline used by boot2 to call read to read data from the disk via
-# the BIOS.  Call with:
-#
-# %cx:%ax	- long    - LBA to read in
-# %es:(%bx)	- caddr_t - buffer to read data into
-# %dl		- byte    - drive to read from
-# %dh		- byte    - num sectors to read
-# 
+// 
+// Trampoline used by boot2 to call read to read data from the disk via
+// the BIOS.  Call with:
+//
+// %cx:%ax	- long    - LBA to read in
+// %es:(%bx)	- caddr_t - buffer to read data into
+// %dl		- byte    - drive to read from
+// %dh		- byte    - num sectors to read
+// 
 
-xread:		push %ss			# Address
-		pop %ds				#  data
-#
-# Setup an EDD disk packet and pass it to read
-# 
-xread.1:					# Starting
-		pushl $0x0			#  absolute
-		push %cx			#  block
-		push %ax			#  number
-		push %es			# Address of
-		push %bx			#  transfer buffer
-		xor %ax,%ax			# Number of
-		movb %dh,%al			#  blocks to
-		push %ax			#  transfer
-		push $0x10			# Size of packet
-		mov %sp,%bp			# Packet pointer
-		callw read			# Read from disk
-		lea 0x10(%bp),%sp		# Clear stack
-		lret				# To far caller
-# 
-# Load the rest of boot2 and BTX up, copy the parts to the right locations,
-# and start it all up.
-#
+xread:		push %ss			// Address
+		pop %ds				//  data
+//
+// Setup an EDD disk packet and pass it to read
+// 
+xread.1:					// Starting
+		pushl $0x0			//  absolute
+		push %cx			//  block
+		push %ax			//  number
+		push %es			// Address of
+		push %bx			//  transfer buffer
+		xor %ax,%ax			// Number of
+		movb %dh,%al			//  blocks to
+		push %ax			//  transfer
+		push $0x10			// Size of packet
+		mov %sp,%bp			// Packet pointer
+		callw read			// Read from disk
+		lea 0x10(%bp),%sp		// Clear stack
+		lret				// To far caller
+// 
+// Load the rest of boot2 and BTX up, copy the parts to the right locations,
+// and start it all up.
+//
 
-#
-# Setup the segment registers to flat addressing (segment 0) and setup the
-# stack to end just below the start of our code.
-# 
-main:		cld				# String ops inc
-		xor %cx,%cx			# Zero
-		mov %cx,%es			# Address
-		mov %cx,%ds			#  data
-		mov %cx,%ss			# Set up
-		mov $start,%sp			#  stack
-#
-# Relocate ourself to MEM_REL.  Since %cx == 0, the inc %ch sets
-# %cx == 0x100.
-# 
-		mov %sp,%si			# Source
-		mov $MEM_REL,%di		# Destination
-		incb %ch			# Word count
-		rep				# Copy
-		movsw				#  code
-#
-# If we are on a hard drive, then load the MBR and look for the first
-# FreeBSD slice.  We use the fake partition entry below that points to
-# the MBR when we call nread.  The first pass looks for the first active
-# FreeBSD slice.  The second pass looks for the first non-active FreeBSD
-# slice if the first one fails.
-# 
-		mov $part4,%si			# Partition
-		cmpb $0x80,%dl			# Hard drive?
-		jb main.4			# No
-		movb $0x1,%dh			# Block count
-		callw nread			# Read MBR
-		mov $0x1,%cx	 		# Two passes
-main.1: 	mov $MEM_BUF+PRT_OFF,%si	# Partition table
-		movb $0x1,%dh			# Partition
-main.2: 	cmpb $PRT_BSD,0x4(%si)		# Our partition type?
-		jne main.3			# No
-		jcxz main.5			# If second pass
-		testb $0x80,(%si)		# Active?
-		jnz main.5			# Yes
-main.3: 	add $0x10,%si	 		# Next entry
-		incb %dh			# Partition
-		cmpb $0x1+PRT_NUM,%dh		# In table?
-		jb main.2			# Yes
-		dec %cx				# Do two
-		jcxz main.1			#  passes
-#
-# If we get here, we didn't find any FreeBSD slices at all, so print an
-# error message and die.
-# 
-		mov $msg_part,%si		# Message
-		jmp error			# Error
-#
-# Floppies use partition 0 of drive 0.
-# 
-main.4: 	xor %dx,%dx			# Partition:drive
-#
-# Ok, we have a slice and drive in %dx now, so use that to locate and load
-# boot2.  %si references the start of the slice we are looking for, so go
-# ahead and load up the first 16 sectors (boot1 + boot2) from that.  When
-# we read it in, we conveniently use 0x8c00 as our transfer buffer.  Thus,
-# boot1 ends up at 0x8c00, and boot2 starts at 0x8c00 + 0x200 = 0x8e00.
-# The first part of boot2 is the disklabel, which is 0x200 bytes long.
-# The second part is BTX, which is thus loaded into 0x9000, which is where
-# it also runs from.  The boot2.bin binary starts right after the end of
-# BTX, so we have to figure out where the start of it is and then move the
-# binary to 0xb000.  Normally, BTX clients start at MEM_USR, or 0xa000, but
-# when we use btxld to create boot2, we use an entry point of 0x1000.  That
-# entry point is relative to MEM_USR; thus boot2.bin starts at 0xb000.
-# 
-main.5: 	mov %dx,MEM_ARG			# Save args
-		movb $0x14,%dh			# Sector count
-		callw nread			# Read disk
-		mov $MEM_BTX,%bx		# BTX
-		mov 0xa(%bx),%si		# Get BTX length and set
-		add %bx,%si			#  %si to start of boot2.bin
-		mov $MEM_USR+SIZ_PAG,%di	# Client page 1
-		mov $MEM_BTX+0x12*SIZ_SEC,%cx	# Byte
-		sub %si,%cx			#  count
-		rep				# Relocate
-		movsb				#  client
-		sub %di,%cx			# Byte count
-		xorb %al,%al			# Zero assumed bss from
-		rep				#  the end of boot2.bin
-		stosb				#  up to 0x10000
-		callw seta20			# Enable A20
-		jmp start+MEM_JMP-MEM_ORG	# Start BTX
-# 
-# Enable A20 so we can access memory above 1 meg.
-# 
-seta20: 	cli				# Disable interrupts
-seta20.1:	inb $0x64,%al			# Get status
-		testb $0x2,%al			# Busy?
-		jnz seta20.1			# Yes
-		movb $0xd1,%al			# Command: Write
-		outb %al,$0x64			#  output port
-seta20.2:	inb $0x64,%al			# Get status
-		testb $0x2,%al			# Busy?
-		jnz seta20.2			# Yes
-		movb $0xdf,%al			# Enable
-		outb %al,$0x60			#  A20
-		sti				# Enable interrupts
-		retw				# To caller
-# 
-# Trampoline used to call read from within boot1.
-# 
-nread:		mov $MEM_BUF,%bx		# Transfer buffer
-		mov 0x8(%si),%ax		# Get
-		mov 0xa(%si),%cx		#  LBA
-		push %cs			# Read from
-		callw xread.1	 		#  disk
-		jnc return			# If success, return
-		mov $msg_read,%si		# Otherwise, set the error
-						#  message and fall through to
-						#  the error routine
-# 
-# Print out the error message pointed to by %ds:(%si) followed
-# by a prompt, wait for a keypress, and then reboot the machine.
-# 
-error:		callw putstr			# Display message
-		mov $prompt,%si			# Display
-		callw putstr			#  prompt
-		xorb %ah,%ah			# BIOS: Get
-		int $0x16			#  keypress
-		movw $0x1234, BDA_BOOT		# Do a warm boot
-		ljmp $0xffff,$0x0		# reboot the machine
-# 
-# Display a null-terminated string using the BIOS output.
-# 
-putstr.0:	mov $0x7,%bx	 		# Page:attribute
-		movb $0xe,%ah			# BIOS: Display
-		int $0x10			#  character
-putstr: 	lodsb				# Get char
-		testb %al,%al			# End of string?
-		jne putstr.0			# No
+//
+// Setup the segment registers to flat addressing (segment 0) and setup the
+// stack to end just below the start of our code.
+// 
+main:		cld				// String ops inc
+		xor %cx,%cx			// Zero
+		mov %cx,%es			// Address
+		mov %cx,%ds			//  data
+		mov %cx,%ss			// Set up
+		mov $start,%sp			//  stack
+//
+// Relocate ourself to MEM_REL.  Since %cx == 0, the inc %ch sets
+// %cx == 0x100.
+// 
+		mov %sp,%si			// Source
+		mov $MEM_REL,%di		// Destination
+		incb %ch			// Word count
+		rep				// Copy
+		movsw				//  code
+//
+// If we are on a hard drive, then load the MBR and look for the first
+// FreeBSD slice.  We use the fake partition entry below that points to
+// the MBR when we call nread.  The first pass looks for the first active
+// FreeBSD slice.  The second pass looks for the first non-active FreeBSD
+// slice if the first one fails.
+// 
+		mov $part4,%si			// Partition
+		cmpb $0x80,%dl			// Hard drive?
+		jb main.4			// No
+		movb $0x1,%dh			// Block count
+		callw nread			// Read MBR
+		mov $0x1,%cx	 		// Two passes
+main.1: 	mov $MEM_BUF+PRT_OFF,%si	// Partition table
+		movb $0x1,%dh			// Partition
+main.2: 	cmpb $PRT_BSD,0x4(%si)		// Our partition type?
+		jne main.3			// No
+		jcxz main.5			// If second pass
+		testb $0x80,(%si)		// Active?
+		jnz main.5			// Yes
+main.3: 	add $0x10,%si	 		// Next entry
+		incb %dh			// Partition
+		cmpb $0x1+PRT_NUM,%dh		// In table?
+		jb main.2			// Yes
+		dec %cx				// Do two
+		jcxz main.1			//  passes
+//
+// If we get here, we didn't find any FreeBSD slices at all, so print an
+// error message and die.
+// 
+		mov $msg_part,%si		// Message
+		jmp error			// Error
+//
+// Floppies use partition 0 of drive 0.
+// 
+main.4: 	xor %dx,%dx			// Partition:drive
+//
+// Ok, we have a slice and drive in %dx now, so use that to locate and load
+// boot2.  %si references the start of the slice we are looking for, so go
+// ahead and load up the first 16 sectors (boot1 + boot2) from that.  When
+// we read it in, we conveniently use 0x8c00 as our transfer buffer.  Thus,
+// boot1 ends up at 0x8c00, and boot2 starts at 0x8c00 + 0x200 = 0x8e00.
+// The first part of boot2 is the disklabel, which is 0x200 bytes long.
+// The second part is BTX, which is thus loaded into 0x9000, which is where
+// it also runs from.  The boot2.bin binary starts right after the end of
+// BTX, so we have to figure out where the start of it is and then move the
+// binary to 0xb000.  Normally, BTX clients start at MEM_USR, or 0xa000, but
+// when we use btxld to create boot2, we use an entry point of 0x1000.  That
+// entry point is relative to MEM_USR; thus boot2.bin starts at 0xb000.
+// 
+main.5: 	mov %dx,MEM_ARG			// Save args
+		movb $0x14,%dh			// Sector count
+		callw nread			// Read disk
+		mov $MEM_BTX,%bx		// BTX
+		mov 0xa(%bx),%si		// Get BTX length and set
+		add %bx,%si			//  %si to start of boot2.bin
+		mov $MEM_USR+SIZ_PAG,%di	// Client page 1
+		mov $MEM_BTX+0x12*SIZ_SEC,%cx	// Byte
+		sub %si,%cx			//  count
+		rep				// Relocate
+		movsb				//  client
+		sub %di,%cx			// Byte count
+		xorb %al,%al			// Zero assumed bss from
+		rep				//  the end of boot2.bin
+		stosb				//  up to 0x10000
+		callw seta20			// Enable A20
+		jmp start+MEM_JMP-MEM_ORG	// Start BTX
+// 
+// Enable A20 so we can access memory above 1 meg.
+// 
+seta20: 	cli				// Disable interrupts
+seta20.1:	inb $0x64,%al			// Get status
+		testb $0x2,%al			// Busy?
+		jnz seta20.1			// Yes
+		movb $0xd1,%al			// Command: Write
+		outb %al,$0x64			//  output port
+seta20.2:	inb $0x64,%al			// Get status
+		testb $0x2,%al			// Busy?
+		jnz seta20.2			// Yes
+		movb $0xdf,%al			// Enable
+		outb %al,$0x60			//  A20
+		sti				// Enable interrupts
+		retw				// To caller
+// 
+// Trampoline used to call read from within boot1.
+// 
+nread:		mov $MEM_BUF,%bx		// Transfer buffer
+		mov 0x8(%si),%ax		// Get
+		mov 0xa(%si),%cx		//  LBA
+		push %cs			// Read from
+		callw xread.1	 		//  disk
+		jnc return			// If success, return
+		mov $msg_read,%si		// Otherwise, set the error
+						//  message and fall through to
+						//  the error routine
+// 
+// Print out the error message pointed to by %ds:(%si) followed
+// by a prompt, wait for a keypress, and then reboot the machine.
+// 
+error:		callw putstr			// Display message
+		mov $prompt,%si			// Display
+		callw putstr			//  prompt
+		xorb %ah,%ah			// BIOS: Get
+		int $0x16			//  keypress
+		movw $0x1234, BDA_BOOT		// Do a warm boot
+		ljmp $0xffff,$0x0		// reboot the machine
+// 
+// Display a null-terminated string using the BIOS output.
+// 
+putstr.0:	mov $0x7,%bx	 		// Page:attribute
+		movb $0xe,%ah			// BIOS: Display
+		int $0x10			//  character
+putstr: 	lodsb				// Get char
+		testb %al,%al			// End of string?
+		jne putstr.0			// No
 
-#
-# Overused return code.  ereturn is used to return an error from the
-# read function.  Since we assume putstr succeeds, we (ab)use the
-# same code when we return from putstr. 
-# 
-ereturn:	movb $0x1,%ah			# Invalid
-		stc				#  argument
-return: 	retw				# To caller
-# 
-# Reads sectors from the disk.  If EDD is enabled, then check if it is
-# installed and use it if it is.  If it is not installed or not enabled, then
-# fall back to using CHS.  Since we use a LBA, if we are using CHS, we have to
-# fetch the drive parameters from the BIOS and divide it out ourselves.
-# Call with:
-#
-# %dl	- byte     - drive number
-# stack - 10 bytes - EDD Packet
-#
-read:	 	push %dx			# Save
-		movb $0x8,%ah			# BIOS: Get drive
-		int $0x13			#  parameters
-		movb %dh,%ch			# Max head number
-		pop %dx				# Restore
-		jc return			# If error
-		andb $0x3f,%cl			# Sectors per track
-		jz ereturn			# If zero
-		cli				# Disable interrupts
-		mov 0x8(%bp),%eax		# Get LBA
-		push %dx			# Save
-		movzbl %cl,%ebx			# Divide by
-		xor %edx,%edx			#  sectors
-		div %ebx			#  per track
-		movb %ch,%bl			# Max head number
-		movb %dl,%ch			# Sector number
-		inc %bx				# Divide by
-		xorb %dl,%dl			#  number
-		div %ebx			#  of heads
-		movb %dl,%bh			# Head number
-		pop %dx				# Restore
-		cmpl $0x3ff,%eax		# Cylinder number supportable?
-		sti				# Enable interrupts
-		ja read.7			# No, try EDD
-		xchgb %al,%ah			# Set up cylinder
-		rorb $0x2,%al			#  number
-		orb %ch,%al			# Merge
-		inc %ax				#  sector
-		xchg %ax,%cx	 		#  number
-		movb %bh,%dh			# Head number
-		subb %ah,%al			# Sectors this track
-		mov 0x2(%bp),%ah		# Blocks to read
-		cmpb %ah,%al			# To read
-		jb read.2			#  this
-		movb %ah,%al			#  track
-read.2: 	mov $0x5,%di	 		# Try count
-read.3: 	les 0x4(%bp),%bx		# Transfer buffer
-		push %ax			# Save
-		movb $0x2,%ah			# BIOS: Read
-		int $0x13			#  from disk
-		pop %bx				# Restore
-		jnc read.4			# If success
-		dec %di				# Retry?
-		jz read.6			# No
-		xorb %ah,%ah			# BIOS: Reset
-		int $0x13			#  disk system
-		xchg %bx,%ax	 		# Block count
-		jmp read.3			# Continue
-read.4: 	movzbw %bl,%ax	 		# Sectors read
-		add %ax,0x8(%bp)		# Adjust
-		jnc read.5			#  LBA,
-		incw 0xa(%bp)	 		#  transfer
-read.5: 	shlb %bl			#  buffer
-		add %bl,0x5(%bp)		#  pointer,
-		sub %al,0x2(%bp)		#  block count
-		ja read				# If not done
-read.6: 	retw				# To caller
-read.7:		testb $FL_PACKET,%cs:MEM_REL+flags-start # LBA support enabled?
-		jz ereturn			# No, so return an error
-		mov $0x55aa,%bx			# Magic
-		push %dx			# Save
-		movb $0x41,%ah			# BIOS: Check
-		int $0x13			#  extensions present
-		pop %dx				# Restore
-		jc return			# If error, return an error
-		cmp $0xaa55,%bx			# Magic?
-		jne ereturn			# No, so return an error
-		testb $0x1,%cl			# Packet interface?
-		jz ereturn			# No, so return an error
-		mov %bp,%si			# Disk packet
-		movb $0x42,%ah			# BIOS: Extended
-		int $0x13			#  read
-		retw				# To caller
+//
+// Overused return code.  ereturn is used to return an error from the
+// read function.  Since we assume putstr succeeds, we (ab)use the
+// same code when we return from putstr. 
+// 
+ereturn:	movb $0x1,%ah			// Invalid
+		stc				//  argument
+return: 	retw				// To caller
+// 
+// Reads sectors from the disk.  If EDD is enabled, then check if it is
+// installed and use it if it is.  If it is not installed or not enabled, then
+// fall back to using CHS.  Since we use a LBA, if we are using CHS, we have to
+// fetch the drive parameters from the BIOS and divide it out ourselves.
+// Call with:
+//
+// %dl	- byte     - drive number
+// stack - 10 bytes - EDD Packet
+//
+read:	 	push %dx			// Save
+		movb $0x8,%ah			// BIOS: Get drive
+		int $0x13			//  parameters
+		movb %dh,%ch			// Max head number
+		pop %dx				// Restore
+		jc return			// If error
+		andb $0x3f,%cl			// Sectors per track
+		jz ereturn			// If zero
+		cli				// Disable interrupts
+		mov 0x8(%bp),%eax		// Get LBA
+		push %dx			// Save
+		movzbl %cl,%ebx			// Divide by
+		xor %edx,%edx			//  sectors
+		div %ebx			//  per track
+		movb %ch,%bl			// Max head number
+		movb %dl,%ch			// Sector number
+		inc %bx				// Divide by
+		xorb %dl,%dl			//  number
+		div %ebx			//  of heads
+		movb %dl,%bh			// Head number
+		pop %dx				// Restore
+		cmpl $0x3ff,%eax		// Cylinder number supportable?
+		sti				// Enable interrupts
+		ja read.7			// No, try EDD
+		xchgb %al,%ah			// Set up cylinder
+		rorb $0x2,%al			//  number
+		orb %ch,%al			// Merge
+		inc %ax				//  sector
+		xchg %ax,%cx	 		//  number
+		movb %bh,%dh			// Head number
+		subb %ah,%al			// Sectors this track
+		mov 0x2(%bp),%ah		// Blocks to read
+		cmpb %ah,%al			// To read
+		jb read.2			//  this
+		movb %ah,%al			//  track
+read.2: 	mov $0x5,%di	 		// Try count
+read.3: 	les 0x4(%bp),%bx		// Transfer buffer
+		push %ax			// Save
+		movb $0x2,%ah			// BIOS: Read
+		int $0x13			//  from disk
+		pop %bx				// Restore
+		jnc read.4			// If success
+		dec %di				// Retry?
+		jz read.6			// No
+		xorb %ah,%ah			// BIOS: Reset
+		int $0x13			//  disk system
+		xchg %bx,%ax	 		// Block count
+		jmp read.3			// Continue
+read.4: 	movzbw %bl,%ax	 		// Sectors read
+		add %ax,0x8(%bp)		// Adjust
+		jnc read.5			//  LBA,
+		incw 0xa(%bp)	 		//  transfer
+read.5: 	shlb %bl			//  buffer
+		add %bl,0x5(%bp)		//  pointer,
+		sub %al,0x2(%bp)		//  block count
+		ja read				// If not done
+read.6: 	retw				// To caller
+read.7:		testb $FL_PACKET,%cs:MEM_REL+flags-start // LBA support enabled?
+		jz ereturn			// No, so return an error
+		mov $0x55aa,%bx			// Magic
+		push %dx			// Save
+		movb $0x41,%ah			// BIOS: Check
+		int $0x13			//  extensions present
+		pop %dx				// Restore
+		jc return			// If error, return an error
+		cmp $0xaa55,%bx			// Magic?
+		jne ereturn			// No, so return an error
+		testb $0x1,%cl			// Packet interface?
+		jz ereturn			// No, so return an error
+		mov %bp,%si			// Disk packet
+		movb $0x42,%ah			// BIOS: Extended
+		int $0x13			//  read
+		retw				// To caller
 
-# Messages
+// Messages
 
 msg_read:	.asciz "Read"
 msg_part:	.asciz "Boot"
 
 prompt: 	.asciz " error\r\n"
 
-flags:		.byte FLAGS			# Flags
+flags:		.byte FLAGS			// Flags
 
 		.org PRT_OFF,0x90
 
-# Partition table
+// Partition table
 
 		.fill 0x30,0x1,0x0
 part4:		.byte 0x80, 0x00, 0x01, 0x00
 		.byte 0xa5, 0xfe, 0xff, 0xff
 		.byte 0x00, 0x00, 0x00, 0x00
-		.byte 0x50, 0xc3, 0x00, 0x00	# 50000 sectors long, bleh
+		.byte 0x50, 0xc3, 0x00, 0x00	// 50000 sectors long, bleh
 
-		.word 0xaa55			# Magic number
+		.word 0xaa55			// Magic number
diff --git a/sys/boot/i386/boot2/boot1.s b/sys/boot/i386/boot2/boot1.s
index 50a6d01..29f9560 100644
--- a/sys/boot/i386/boot2/boot1.s
+++ b/sys/boot/i386/boot2/boot1.s
@@ -1,360 +1,360 @@
-#
-# Copyright (c) 1998 Robert Nordier
-# All rights reserved.
-#
-# Redistribution and use in source and binary forms are freely
-# permitted provided that the above copyright notice and this
-# paragraph and the following disclaimer are duplicated in all
-# such forms.
-#
-# This software is provided "AS IS" and without any express or
-# implied warranties, including, without limitation, the implied
-# warranties of merchantability and fitness for a particular
-# purpose.
-#
+//
+// Copyright (c) 1998 Robert Nordier
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms are freely
+// permitted provided that the above copyright notice and this
+// paragraph and the following disclaimer are duplicated in all
+// such forms.
+//
+// This software is provided "AS IS" and without any express or
+// implied warranties, including, without limitation, the implied
+// warranties of merchantability and fitness for a particular
+// purpose.
+//
 
-# $FreeBSD$
+// $FreeBSD$
 
-# Memory Locations
-		.set MEM_REL,0x700		# Relocation address
-		.set MEM_ARG,0x900		# Arguments
-		.set MEM_ORG,0x7c00		# Origin
-		.set MEM_BUF,0x8c00		# Load area
-		.set MEM_BTX,0x9000		# BTX start
-		.set MEM_JMP,0x9010		# BTX entry point
-		.set MEM_USR,0xb000		# Client start
-		.set BDA_BOOT,0x472		# Boot howto flag
+// Memory Locations
+		.set MEM_REL,0x700		// Relocation address
+		.set MEM_ARG,0x900		// Arguments
+		.set MEM_ORG,0x7c00		// Origin
+		.set MEM_BUF,0x8c00		// Load area
+		.set MEM_BTX,0x9000		// BTX start
+		.set MEM_JMP,0x9010		// BTX entry point
+		.set MEM_USR,0xb000		// Client start
+		.set BDA_BOOT,0x472		// Boot howto flag
 	
-# Partition Constants 
-		.set PRT_OFF,0x1be		# Partition offset
-		.set PRT_NUM,0x4		# Partitions
-		.set PRT_BSD,0xa5		# Partition type
+// Partition Constants 
+		.set PRT_OFF,0x1be		// Partition offset
+		.set PRT_NUM,0x4		// Partitions
+		.set PRT_BSD,0xa5		// Partition type
 
-# Flag Bits
-		.set FL_PACKET,0x80		# Packet mode
+// Flag Bits
+		.set FL_PACKET,0x80		// Packet mode
 
-# Misc. Constants
-		.set SIZ_PAG,0x1000		# Page size
-		.set SIZ_SEC,0x200		# Sector size
+// Misc. Constants
+		.set SIZ_PAG,0x1000		// Page size
+		.set SIZ_SEC,0x200		// Sector size
 
 		.globl start
 		.globl xread
 		.code16
 
-start:		jmp main			# Start recognizably
+start:		jmp main			// Start recognizably
 
-# This is the start of a standard BIOS Parameter Block (BPB). Most bootable
-# FAT disks have this at the start of their MBR. While normal BIOS's will
-# work fine without this section, IBM's El Torito emulation "fixes" up the
-# BPB by writing into the memory copy of the MBR. Rather than have data
-# written into our xread routine, we'll define a BPB to work around it.
-# The data marked with (T) indicates a field required for a ThinkPad to
-# recognize the disk and (W) indicates fields written from IBM BIOS code.
-# The use of the BPB is based on what OpenBSD and NetBSD implemented in
-# their boot code but the required fields were determined by trial and error.
-#
-# Note: If additional space is needed in boot1, one solution would be to
-# move the "prompt" message data (below) to replace the OEM ID.
+// This is the start of a standard BIOS Parameter Block (BPB). Most bootable
+// FAT disks have this at the start of their MBR. While normal BIOS's will
+// work fine without this section, IBM's El Torito emulation "fixes" up the
+// BPB by writing into the memory copy of the MBR. Rather than have data
+// written into our xread routine, we'll define a BPB to work around it.
+// The data marked with (T) indicates a field required for a ThinkPad to
+// recognize the disk and (W) indicates fields written from IBM BIOS code.
+// The use of the BPB is based on what OpenBSD and NetBSD implemented in
+// their boot code but the required fields were determined by trial and error.
+//
+// Note: If additional space is needed in boot1, one solution would be to
+// move the "prompt" message data (below) to replace the OEM ID.
 
 		.org 0x03, 0x00
-oemid:		.space 0x08, 0x00	# OEM ID
+oemid:		.space 0x08, 0x00	// OEM ID
 
 		.org 0x0b, 0x00
-bpb:		.word   512		# sector size (T)
-		.byte	0		# sectors/clustor
-		.word	0		# reserved sectors
-		.byte	0		# number of FATs
-		.word	0		# root entries
-		.word	0		# small sectors
-		.byte	0		# media type (W)
-		.word	0		# sectors/fat
-		.word	18		# sectors per track (T)
-		.word	2		# number of heads (T)
-		.long	0		# hidden sectors (W)
-		.long	0		# large sectors
+bpb:		.word   512		// sector size (T)
+		.byte	0		// sectors/clustor
+		.word	0		// reserved sectors
+		.byte	0		// number of FATs
+		.word	0		// root entries
+		.word	0		// small sectors
+		.byte	0		// media type (W)
+		.word	0		// sectors/fat
+		.word	18		// sectors per track (T)
+		.word	2		// number of heads (T)
+		.long	0		// hidden sectors (W)
+		.long	0		// large sectors
 
 		.org 0x24, 0x00
-ebpb:		.byte	0		# BIOS physical drive number (W)
+ebpb:		.byte	0		// BIOS physical drive number (W)
 
 		.org 0x25,0x90
-# 
-# Trampoline used by boot2 to call read to read data from the disk via
-# the BIOS.  Call with:
-#
-# %cx:%ax	- long    - LBA to read in
-# %es:(%bx)	- caddr_t - buffer to read data into
-# %dl		- byte    - drive to read from
-# %dh		- byte    - num sectors to read
-# 
+// 
+// Trampoline used by boot2 to call read to read data from the disk via
+// the BIOS.  Call with:
+//
+// %cx:%ax	- long    - LBA to read in
+// %es:(%bx)	- caddr_t - buffer to read data into
+// %dl		- byte    - drive to read from
+// %dh		- byte    - num sectors to read
+// 
 
-xread:		push %ss			# Address
-		pop %ds				#  data
-#
-# Setup an EDD disk packet and pass it to read
-# 
-xread.1:					# Starting
-		pushl $0x0			#  absolute
-		push %cx			#  block
-		push %ax			#  number
-		push %es			# Address of
-		push %bx			#  transfer buffer
-		xor %ax,%ax			# Number of
-		movb %dh,%al			#  blocks to
-		push %ax			#  transfer
-		push $0x10			# Size of packet
-		mov %sp,%bp			# Packet pointer
-		callw read			# Read from disk
-		lea 0x10(%bp),%sp		# Clear stack
-		lret				# To far caller
-# 
-# Load the rest of boot2 and BTX up, copy the parts to the right locations,
-# and start it all up.
-#
+xread:		push %ss			// Address
+		pop %ds				//  data
+//
+// Setup an EDD disk packet and pass it to read
+// 
+xread.1:					// Starting
+		pushl $0x0			//  absolute
+		push %cx			//  block
+		push %ax			//  number
+		push %es			// Address of
+		push %bx			//  transfer buffer
+		xor %ax,%ax			// Number of
+		movb %dh,%al			//  blocks to
+		push %ax			//  transfer
+		push $0x10			// Size of packet
+		mov %sp,%bp			// Packet pointer
+		callw read			// Read from disk
+		lea 0x10(%bp),%sp		// Clear stack
+		lret				// To far caller
+// 
+// Load the rest of boot2 and BTX up, copy the parts to the right locations,
+// and start it all up.
+//
 
-#
-# Setup the segment registers to flat addressing (segment 0) and setup the
-# stack to end just below the start of our code.
-# 
-main:		cld				# String ops inc
-		xor %cx,%cx			# Zero
-		mov %cx,%es			# Address
-		mov %cx,%ds			#  data
-		mov %cx,%ss			# Set up
-		mov $start,%sp			#  stack
-#
-# Relocate ourself to MEM_REL.  Since %cx == 0, the inc %ch sets
-# %cx == 0x100.
-# 
-		mov %sp,%si			# Source
-		mov $MEM_REL,%di		# Destination
-		incb %ch			# Word count
-		rep				# Copy
-		movsw				#  code
-#
-# If we are on a hard drive, then load the MBR and look for the first
-# FreeBSD slice.  We use the fake partition entry below that points to
-# the MBR when we call nread.  The first pass looks for the first active
-# FreeBSD slice.  The second pass looks for the first non-active FreeBSD
-# slice if the first one fails.
-# 
-		mov $part4,%si			# Partition
-		cmpb $0x80,%dl			# Hard drive?
-		jb main.4			# No
-		movb $0x1,%dh			# Block count
-		callw nread			# Read MBR
-		mov $0x1,%cx	 		# Two passes
-main.1: 	mov $MEM_BUF+PRT_OFF,%si	# Partition table
-		movb $0x1,%dh			# Partition
-main.2: 	cmpb $PRT_BSD,0x4(%si)		# Our partition type?
-		jne main.3			# No
-		jcxz main.5			# If second pass
-		testb $0x80,(%si)		# Active?
-		jnz main.5			# Yes
-main.3: 	add $0x10,%si	 		# Next entry
-		incb %dh			# Partition
-		cmpb $0x1+PRT_NUM,%dh		# In table?
-		jb main.2			# Yes
-		dec %cx				# Do two
-		jcxz main.1			#  passes
-#
-# If we get here, we didn't find any FreeBSD slices at all, so print an
-# error message and die.
-# 
-		mov $msg_part,%si		# Message
-		jmp error			# Error
-#
-# Floppies use partition 0 of drive 0.
-# 
-main.4: 	xor %dx,%dx			# Partition:drive
-#
-# Ok, we have a slice and drive in %dx now, so use that to locate and load
-# boot2.  %si references the start of the slice we are looking for, so go
-# ahead and load up the first 16 sectors (boot1 + boot2) from that.  When
-# we read it in, we conveniently use 0x8c00 as our transfer buffer.  Thus,
-# boot1 ends up at 0x8c00, and boot2 starts at 0x8c00 + 0x200 = 0x8e00.
-# The first part of boot2 is the disklabel, which is 0x200 bytes long.
-# The second part is BTX, which is thus loaded into 0x9000, which is where
-# it also runs from.  The boot2.bin binary starts right after the end of
-# BTX, so we have to figure out where the start of it is and then move the
-# binary to 0xb000.  Normally, BTX clients start at MEM_USR, or 0xa000, but
-# when we use btxld to create boot2, we use an entry point of 0x1000.  That
-# entry point is relative to MEM_USR; thus boot2.bin starts at 0xb000.
-# 
-main.5: 	mov %dx,MEM_ARG			# Save args
-		movb $0x14,%dh			# Sector count
-		callw nread			# Read disk
-		mov $MEM_BTX,%bx		# BTX
-		mov 0xa(%bx),%si		# Get BTX length and set
-		add %bx,%si			#  %si to start of boot2.bin
-		mov $MEM_USR+SIZ_PAG,%di	# Client page 1
-		mov $MEM_BTX+0x12*SIZ_SEC,%cx	# Byte
-		sub %si,%cx			#  count
-		rep				# Relocate
-		movsb				#  client
-		sub %di,%cx			# Byte count
-		xorb %al,%al			# Zero assumed bss from
-		rep				#  the end of boot2.bin
-		stosb				#  up to 0x10000
-		callw seta20			# Enable A20
-		jmp start+MEM_JMP-MEM_ORG	# Start BTX
-# 
-# Enable A20 so we can access memory above 1 meg.
-# 
-seta20: 	cli				# Disable interrupts
-seta20.1:	inb $0x64,%al			# Get status
-		testb $0x2,%al			# Busy?
-		jnz seta20.1			# Yes
-		movb $0xd1,%al			# Command: Write
-		outb %al,$0x64			#  output port
-seta20.2:	inb $0x64,%al			# Get status
-		testb $0x2,%al			# Busy?
-		jnz seta20.2			# Yes
-		movb $0xdf,%al			# Enable
-		outb %al,$0x60			#  A20
-		sti				# Enable interrupts
-		retw				# To caller
-# 
-# Trampoline used to call read from within boot1.
-# 
-nread:		mov $MEM_BUF,%bx		# Transfer buffer
-		mov 0x8(%si),%ax		# Get
-		mov 0xa(%si),%cx		#  LBA
-		push %cs			# Read from
-		callw xread.1	 		#  disk
-		jnc return			# If success, return
-		mov $msg_read,%si		# Otherwise, set the error
-						#  message and fall through to
-						#  the error routine
-# 
-# Print out the error message pointed to by %ds:(%si) followed
-# by a prompt, wait for a keypress, and then reboot the machine.
-# 
-error:		callw putstr			# Display message
-		mov $prompt,%si			# Display
-		callw putstr			#  prompt
-		xorb %ah,%ah			# BIOS: Get
-		int $0x16			#  keypress
-		movw $0x1234, BDA_BOOT		# Do a warm boot
-		ljmp $0xffff,$0x0		# reboot the machine
-# 
-# Display a null-terminated string using the BIOS output.
-# 
-putstr.0:	mov $0x7,%bx	 		# Page:attribute
-		movb $0xe,%ah			# BIOS: Display
-		int $0x10			#  character
-putstr: 	lodsb				# Get char
-		testb %al,%al			# End of string?
-		jne putstr.0			# No
+//
+// Setup the segment registers to flat addressing (segment 0) and setup the
+// stack to end just below the start of our code.
+// 
+main:		cld				// String ops inc
+		xor %cx,%cx			// Zero
+		mov %cx,%es			// Address
+		mov %cx,%ds			//  data
+		mov %cx,%ss			// Set up
+		mov $start,%sp			//  stack
+//
+// Relocate ourself to MEM_REL.  Since %cx == 0, the inc %ch sets
+// %cx == 0x100.
+// 
+		mov %sp,%si			// Source
+		mov $MEM_REL,%di		// Destination
+		incb %ch			// Word count
+		rep				// Copy
+		movsw				//  code
+//
+// If we are on a hard drive, then load the MBR and look for the first
+// FreeBSD slice.  We use the fake partition entry below that points to
+// the MBR when we call nread.  The first pass looks for the first active
+// FreeBSD slice.  The second pass looks for the first non-active FreeBSD
+// slice if the first one fails.
+// 
+		mov $part4,%si			// Partition
+		cmpb $0x80,%dl			// Hard drive?
+		jb main.4			// No
+		movb $0x1,%dh			// Block count
+		callw nread			// Read MBR
+		mov $0x1,%cx	 		// Two passes
+main.1: 	mov $MEM_BUF+PRT_OFF,%si	// Partition table
+		movb $0x1,%dh			// Partition
+main.2: 	cmpb $PRT_BSD,0x4(%si)		// Our partition type?
+		jne main.3			// No
+		jcxz main.5			// If second pass
+		testb $0x80,(%si)		// Active?
+		jnz main.5			// Yes
+main.3: 	add $0x10,%si	 		// Next entry
+		incb %dh			// Partition
+		cmpb $0x1+PRT_NUM,%dh		// In table?
+		jb main.2			// Yes
+		dec %cx				// Do two
+		jcxz main.1			//  passes
+//
+// If we get here, we didn't find any FreeBSD slices at all, so print an
+// error message and die.
+// 
+		mov $msg_part,%si		// Message
+		jmp error			// Error
+//
+// Floppies use partition 0 of drive 0.
+// 
+main.4: 	xor %dx,%dx			// Partition:drive
+//
+// Ok, we have a slice and drive in %dx now, so use that to locate and load
+// boot2.  %si references the start of the slice we are looking for, so go
+// ahead and load up the first 16 sectors (boot1 + boot2) from that.  When
+// we read it in, we conveniently use 0x8c00 as our transfer buffer.  Thus,
+// boot1 ends up at 0x8c00, and boot2 starts at 0x8c00 + 0x200 = 0x8e00.
+// The first part of boot2 is the disklabel, which is 0x200 bytes long.
+// The second part is BTX, which is thus loaded into 0x9000, which is where
+// it also runs from.  The boot2.bin binary starts right after the end of
+// BTX, so we have to figure out where the start of it is and then move the
+// binary to 0xb000.  Normally, BTX clients start at MEM_USR, or 0xa000, but
+// when we use btxld to create boot2, we use an entry point of 0x1000.  That
+// entry point is relative to MEM_USR; thus boot2.bin starts at 0xb000.
+// 
+main.5: 	mov %dx,MEM_ARG			// Save args
+		movb $0x14,%dh			// Sector count
+		callw nread			// Read disk
+		mov $MEM_BTX,%bx		// BTX
+		mov 0xa(%bx),%si		// Get BTX length and set
+		add %bx,%si			//  %si to start of boot2.bin
+		mov $MEM_USR+SIZ_PAG,%di	// Client page 1
+		mov $MEM_BTX+0x12*SIZ_SEC,%cx	// Byte
+		sub %si,%cx			//  count
+		rep				// Relocate
+		movsb				//  client
+		sub %di,%cx			// Byte count
+		xorb %al,%al			// Zero assumed bss from
+		rep				//  the end of boot2.bin
+		stosb				//  up to 0x10000
+		callw seta20			// Enable A20
+		jmp start+MEM_JMP-MEM_ORG	// Start BTX
+// 
+// Enable A20 so we can access memory above 1 meg.
+// 
+seta20: 	cli				// Disable interrupts
+seta20.1:	inb $0x64,%al			// Get status
+		testb $0x2,%al			// Busy?
+		jnz seta20.1			// Yes
+		movb $0xd1,%al			// Command: Write
+		outb %al,$0x64			//  output port
+seta20.2:	inb $0x64,%al			// Get status
+		testb $0x2,%al			// Busy?
+		jnz seta20.2			// Yes
+		movb $0xdf,%al			// Enable
+		outb %al,$0x60			//  A20
+		sti				// Enable interrupts
+		retw				// To caller
+// 
+// Trampoline used to call read from within boot1.
+// 
+nread:		mov $MEM_BUF,%bx		// Transfer buffer
+		mov 0x8(%si),%ax		// Get
+		mov 0xa(%si),%cx		//  LBA
+		push %cs			// Read from
+		callw xread.1	 		//  disk
+		jnc return			// If success, return
+		mov $msg_read,%si		// Otherwise, set the error
+						//  message and fall through to
+						//  the error routine
+// 
+// Print out the error message pointed to by %ds:(%si) followed
+// by a prompt, wait for a keypress, and then reboot the machine.
+// 
+error:		callw putstr			// Display message
+		mov $prompt,%si			// Display
+		callw putstr			//  prompt
+		xorb %ah,%ah			// BIOS: Get
+		int $0x16			//  keypress
+		movw $0x1234, BDA_BOOT		// Do a warm boot
+		ljmp $0xffff,$0x0		// reboot the machine
+// 
+// Display a null-terminated string using the BIOS output.
+// 
+putstr.0:	mov $0x7,%bx	 		// Page:attribute
+		movb $0xe,%ah			// BIOS: Display
+		int $0x10			//  character
+putstr: 	lodsb				// Get char
+		testb %al,%al			// End of string?
+		jne putstr.0			// No
 
-#
-# Overused return code.  ereturn is used to return an error from the
-# read function.  Since we assume putstr succeeds, we (ab)use the
-# same code when we return from putstr. 
-# 
-ereturn:	movb $0x1,%ah			# Invalid
-		stc				#  argument
-return: 	retw				# To caller
-# 
-# Reads sectors from the disk.  If EDD is enabled, then check if it is
-# installed and use it if it is.  If it is not installed or not enabled, then
-# fall back to using CHS.  Since we use a LBA, if we are using CHS, we have to
-# fetch the drive parameters from the BIOS and divide it out ourselves.
-# Call with:
-#
-# %dl	- byte     - drive number
-# stack - 10 bytes - EDD Packet
-#
-read:	 	push %dx			# Save
-		movb $0x8,%ah			# BIOS: Get drive
-		int $0x13			#  parameters
-		movb %dh,%ch			# Max head number
-		pop %dx				# Restore
-		jc return			# If error
-		andb $0x3f,%cl			# Sectors per track
-		jz ereturn			# If zero
-		cli				# Disable interrupts
-		mov 0x8(%bp),%eax		# Get LBA
-		push %dx			# Save
-		movzbl %cl,%ebx			# Divide by
-		xor %edx,%edx			#  sectors
-		div %ebx			#  per track
-		movb %ch,%bl			# Max head number
-		movb %dl,%ch			# Sector number
-		inc %bx				# Divide by
-		xorb %dl,%dl			#  number
-		div %ebx			#  of heads
-		movb %dl,%bh			# Head number
-		pop %dx				# Restore
-		cmpl $0x3ff,%eax		# Cylinder number supportable?
-		sti				# Enable interrupts
-		ja read.7			# No, try EDD
-		xchgb %al,%ah			# Set up cylinder
-		rorb $0x2,%al			#  number
-		orb %ch,%al			# Merge
-		inc %ax				#  sector
-		xchg %ax,%cx	 		#  number
-		movb %bh,%dh			# Head number
-		subb %ah,%al			# Sectors this track
-		mov 0x2(%bp),%ah		# Blocks to read
-		cmpb %ah,%al			# To read
-		jb read.2			#  this
-		movb %ah,%al			#  track
-read.2: 	mov $0x5,%di	 		# Try count
-read.3: 	les 0x4(%bp),%bx		# Transfer buffer
-		push %ax			# Save
-		movb $0x2,%ah			# BIOS: Read
-		int $0x13			#  from disk
-		pop %bx				# Restore
-		jnc read.4			# If success
-		dec %di				# Retry?
-		jz read.6			# No
-		xorb %ah,%ah			# BIOS: Reset
-		int $0x13			#  disk system
-		xchg %bx,%ax	 		# Block count
-		jmp read.3			# Continue
-read.4: 	movzbw %bl,%ax	 		# Sectors read
-		add %ax,0x8(%bp)		# Adjust
-		jnc read.5			#  LBA,
-		incw 0xa(%bp)	 		#  transfer
-read.5: 	shlb %bl			#  buffer
-		add %bl,0x5(%bp)		#  pointer,
-		sub %al,0x2(%bp)		#  block count
-		ja read				# If not done
-read.6: 	retw				# To caller
-read.7:		testb $FL_PACKET,%cs:MEM_REL+flags-start # LBA support enabled?
-		jz ereturn			# No, so return an error
-		mov $0x55aa,%bx			# Magic
-		push %dx			# Save
-		movb $0x41,%ah			# BIOS: Check
-		int $0x13			#  extensions present
-		pop %dx				# Restore
-		jc return			# If error, return an error
-		cmp $0xaa55,%bx			# Magic?
-		jne ereturn			# No, so return an error
-		testb $0x1,%cl			# Packet interface?
-		jz ereturn			# No, so return an error
-		mov %bp,%si			# Disk packet
-		movb $0x42,%ah			# BIOS: Extended
-		int $0x13			#  read
-		retw				# To caller
+//
+// Overused return code.  ereturn is used to return an error from the
+// read function.  Since we assume putstr succeeds, we (ab)use the
+// same code when we return from putstr. 
+// 
+ereturn:	movb $0x1,%ah			// Invalid
+		stc				//  argument
+return: 	retw				// To caller
+// 
+// Reads sectors from the disk.  If EDD is enabled, then check if it is
+// installed and use it if it is.  If it is not installed or not enabled, then
+// fall back to using CHS.  Since we use a LBA, if we are using CHS, we have to
+// fetch the drive parameters from the BIOS and divide it out ourselves.
+// Call with:
+//
+// %dl	- byte     - drive number
+// stack - 10 bytes - EDD Packet
+//
+read:	 	push %dx			// Save
+		movb $0x8,%ah			// BIOS: Get drive
+		int $0x13			//  parameters
+		movb %dh,%ch			// Max head number
+		pop %dx				// Restore
+		jc return			// If error
+		andb $0x3f,%cl			// Sectors per track
+		jz ereturn			// If zero
+		cli				// Disable interrupts
+		mov 0x8(%bp),%eax		// Get LBA
+		push %dx			// Save
+		movzbl %cl,%ebx			// Divide by
+		xor %edx,%edx			//  sectors
+		div %ebx			//  per track
+		movb %ch,%bl			// Max head number
+		movb %dl,%ch			// Sector number
+		inc %bx				// Divide by
+		xorb %dl,%dl			//  number
+		div %ebx			//  of heads
+		movb %dl,%bh			// Head number
+		pop %dx				// Restore
+		cmpl $0x3ff,%eax		// Cylinder number supportable?
+		sti				// Enable interrupts
+		ja read.7			// No, try EDD
+		xchgb %al,%ah			// Set up cylinder
+		rorb $0x2,%al			//  number
+		orb %ch,%al			// Merge
+		inc %ax				//  sector
+		xchg %ax,%cx	 		//  number
+		movb %bh,%dh			// Head number
+		subb %ah,%al			// Sectors this track
+		mov 0x2(%bp),%ah		// Blocks to read
+		cmpb %ah,%al			// To read
+		jb read.2			//  this
+		movb %ah,%al			//  track
+read.2: 	mov $0x5,%di	 		// Try count
+read.3: 	les 0x4(%bp),%bx		// Transfer buffer
+		push %ax			// Save
+		movb $0x2,%ah			// BIOS: Read
+		int $0x13			//  from disk
+		pop %bx				// Restore
+		jnc read.4			// If success
+		dec %di				// Retry?
+		jz read.6			// No
+		xorb %ah,%ah			// BIOS: Reset
+		int $0x13			//  disk system
+		xchg %bx,%ax	 		// Block count
+		jmp read.3			// Continue
+read.4: 	movzbw %bl,%ax	 		// Sectors read
+		add %ax,0x8(%bp)		// Adjust
+		jnc read.5			//  LBA,
+		incw 0xa(%bp)	 		//  transfer
+read.5: 	shlb %bl			//  buffer
+		add %bl,0x5(%bp)		//  pointer,
+		sub %al,0x2(%bp)		//  block count
+		ja read				// If not done
+read.6: 	retw				// To caller
+read.7:		testb $FL_PACKET,%cs:MEM_REL+flags-start // LBA support enabled?
+		jz ereturn			// No, so return an error
+		mov $0x55aa,%bx			// Magic
+		push %dx			// Save
+		movb $0x41,%ah			// BIOS: Check
+		int $0x13			//  extensions present
+		pop %dx				// Restore
+		jc return			// If error, return an error
+		cmp $0xaa55,%bx			// Magic?
+		jne ereturn			// No, so return an error
+		testb $0x1,%cl			// Packet interface?
+		jz ereturn			// No, so return an error
+		mov %bp,%si			// Disk packet
+		movb $0x42,%ah			// BIOS: Extended
+		int $0x13			//  read
+		retw				// To caller
 
-# Messages
+// Messages
 
 msg_read:	.asciz "Read"
 msg_part:	.asciz "Boot"
 
 prompt: 	.asciz " error\r\n"
 
-flags:		.byte FLAGS			# Flags
+flags:		.byte FLAGS			// Flags
 
 		.org PRT_OFF,0x90
 
-# Partition table
+// Partition table
 
 		.fill 0x30,0x1,0x0
 part4:		.byte 0x80, 0x00, 0x01, 0x00
 		.byte 0xa5, 0xfe, 0xff, 0xff
 		.byte 0x00, 0x00, 0x00, 0x00
-		.byte 0x50, 0xc3, 0x00, 0x00	# 50000 sectors long, bleh
+		.byte 0x50, 0xc3, 0x00, 0x00	// 50000 sectors long, bleh
 
-		.word 0xaa55			# Magic number
+		.word 0xaa55			// Magic number
diff --git a/sys/boot/i386/gptboot/Makefile b/sys/boot/i386/gptboot/Makefile
index e4ab3f5..4526d15 100644
--- a/sys/boot/i386/gptboot/Makefile
+++ b/sys/boot/i386/gptboot/Makefile
@@ -49,7 +49,8 @@ boot1.out: boot1.o
 	${LD} ${LDFLAGS} -e start -Ttext ${ORG1} -o ${.TARGET} boot1.o
 
 boot1.o: boot1.s
-	${AS} ${AFLAGS} --defsym FLAGS=${B1FLAGS} ${.IMPSRC} -o ${.TARGET}
+	${CPP} ${CFLAGS} ${.IMPSRC} | \
+	    ${AS} ${AFLAGS} --defsym FLAGS=${B1FLAGS} -o ${.TARGET}
 
 boot2.o: boot2.c ${.CURDIR}/../../common/ufsread.c
 	${CC} ${CFLAGS} -S -o boot2.s.tmp ${.IMPSRC}