Mega i386 loader commit.

- Don't hard code 0x10000 as the entry point for the loader.  Instead add
  src/sys/boot/i386/Makefile.inc which defines a make variable with the
  entry point for the loader.  Move the loader's entry point up to
  0x20000, which makes PXE happy.
- Don't try to use cpp to parse btxldr for the optional BTXLDR_VERBOSE,
  instead use m4 to achieve this.  Also, add a BTXLDR_VERBOSE knob in the
  btxldr Makefile to turn this option on.
- Redo parts of cdldr's Makefile so that it now builds and installs cdboot
  instead of having i386/loader/Makefile do that.  Also, add in some more
  variables to make the pxeldr Makefile almost identical and thus to ease
  maintainability.
- Teach cdldr about the a.out format.  Cdldr now parsers the a.out header
  of the loader binary and relocates it based on that.  The entry point of
  the loader no longer has to be hardcoded into cdldr.  Also, the boot
  info table from mkisofs is no longer required to get a useful cdboot.
- Update the lsdev function for BIOS disks to parse other file systems
  (such as DOS FAT) that we currently support.  This is still buggy as
  it assumes that a floppy with a DOS boot sector actually has a MBR and
  parses it as such.  I'll be fixing this in the future.
- The biggie:  Add in support for booting off of PXE-enabled network
  adapters.  Currently, we use the TFTP API provided by the PXE BIOS.
  Eventually we will switch to using the low-level NIC driver thus
  allowing both TFTP and NFS to be used, but for now it's just TFTP.

Submitted by:	ps, alfred
Testing by:	Benno Rice <benno@netizen.com.au>

2 files changed, 91 insertions, 69 deletions

diff --git a/sys/boot/i386/cdldr/Makefile b/sys/boot/i386/cdldr/Makefile
index d57d509..a67f2a7 100644
--- a/sys/boot/i386/cdldr/Makefile
+++ b/sys/boot/i386/cdldr/Makefile
@@ -2,22 +2,39 @@
 
 MAINTAINER=jhb@FreeBSD.org
 
-ORG=0x00
+ORG=		0x7c00
 
-all: cdldr
+LDR=		cdldr
+BOOT=		cdboot
+PROG=		${BOOT}
+NOMAN=
+STRIP=
+BINDIR?=	/boot
 
-cdldr: cdldr.o
+
+.if exists(${.OBJDIR}/../loader)
+LOADER=	${.OBJDIR}/../loader/loader
+.else
+LOADER=	${.CURDIR}/../loader/loader
+.endif
+
+${BOOT}: ${LDR} ${LOADER}
+	cat ${LDR} ${LOADER} > ${.TARGET}.tmp
+	dd if=${.TARGET}.tmp of=${.TARGET} obs=2k conv=osync
+	rm ${.TARGET}.tmp
+
+${LDR}: ${LDR}.o
 .if ${OBJFORMAT} == aout
-	${LD} -nostdlib -N -s -T ${ORG} -o cdldr.out cdldr.o
-	dd if=cdldr.out of=${.TARGET} ibs=32 skip=1
+	${LD} -nostdlib -N -s -T ${ORG} -o ${LDR}.out ${LDR}.o
+	dd if=${LDR}.out of=${.TARGET} ibs=32 skip=1
 .else
-	${LD} -N -e start -Ttext ${ORG} -o cdldr.out cdldr.o
-	objcopy -S -O binary cdldr.out ${.TARGET}
+	${LD} -N -e start -Ttext ${ORG} -o ${LDR}.out ${LDR}.o
+	objcopy -S -O binary ${LDR}.out ${.TARGET}
 .endif
 
-cdldr.o: cdldr.s
-	${AS} ${AFLAGS} -o ${.TARGET} ${.CURDIR}/cdldr.s
+${LDR}.o: ${.CURDIR}/${LDR}.s
+	${AS} ${AFLAGS} -o ${.TARGET} ${.CURDIR}/${LDR}.s
 
-CLEANFILES+= cdldr cdldr.out cdldr.o
+CLEANFILES+= ${LDR} ${LDR}.out ${LDR}.o ${BOOT}.tmp
 
 .include <bsd.prog.mk>
diff --git a/sys/boot/i386/cdldr/cdldr.s b/sys/boot/i386/cdldr/cdldr.s
index 2ad2e30..30ed2fa 100644
--- a/sys/boot/i386/cdldr/cdldr.s
+++ b/sys/boot/i386/cdldr/cdldr.s
@@ -28,20 +28,25 @@
 #
 # Memory locations.
 #
-		.set MEM_LOADER_ADDRESS,0x100000 # where the loader lives
-		.set MEM_LDR_ENTRY,0x7c00	# our entry point
+		.set MEM_PAGE_SIZE,0x1000	# memory page size, 4k
 		.set MEM_ARG,0x900		# Arguments at start
 		.set MEM_ARG_BTX,0xa100		# Where we move them to so the
 						#  BTX client can see them
 		.set MEM_ARG_SIZE,0x18		# Size of the arguments
 		.set MEM_BTX_ADDRESS,0x9000	# where BTX lives
 		.set MEM_BTX_ENTRY,0x9010	# where BTX starts to execute
-		.set MEM_AOUT_HEADER,0x1000	# size of the a.out header
-		.set MEM_BTX_OFFSET,0x1000	# offset of BTX in the loader
-		.set MEM_BTX_IMAGE,MEM_LOADER_ADDRESS+MEM_BTX_OFFSET # where
-						#  BTX is in the loader
+		.set MEM_BTX_OFFSET,MEM_PAGE_SIZE # offset of BTX in the loader
 		.set MEM_BTX_CLIENT,0xa000	# where BTX clients live
 #
+# a.out header fields
+#
+		.set AOUT_TEXT,0x04		# text segment size
+		.set AOUT_DATA,0x08		# data segment size
+		.set AOUT_BSS,0x0c		# zero'd BSS size
+		.set AOUT_SYMBOLS,0x10		# symbol table
+		.set AOUT_ENTRY,0x14		# entry point
+		.set AOUT_HEADER,MEM_PAGE_SIZE	# size of the a.out header
+#
 # Flags for kargs->bootflags
 #
 		.set KARGS_FLAGS_CD,0x1		# flag to indicate booting from
@@ -58,7 +63,8 @@
 #
 		.set INT_SYS,0x30		# BTX syscall interrupt
 #
-# We expect to be loaded by the BIOS at 0x7c00 (standard boot loader entry point)
+# We expect to be loaded by the BIOS at 0x7c00 (standard boot loader entry
+# point)
 #
 		.code16
 		.globl start
@@ -66,40 +72,22 @@
 #
 # BTX program loader for CD booting
 #
-start:		jmp begin			# skip the boot info table
-		.org 0x8, 0x90			# fill with nops up to the table
-#
-# Boot information table that is filled in by mkisofs(8), see the man page for
-# details
-#
-boot_info_table:
-bi_pvd_LBA:	.long 0x0
-bi_file_LBA:	.long 0x0
-bi_file_length:	.long 0x0
-bi_checksum:	.long 0x0
-bi_reserved:	.byte 0x0
-		.org 0x40, 0x0
-#
-# Actual start of execution
-#
-begin:		cld				# string ops inc
+start:		cld				# string ops inc
 		xorw %ax, %ax			# zero %ax
 		movw %ax, %ss			# setup the
-		movw $MEM_LDR_ENTRY, %sp	#  stack
+		movw $start, %sp		#  stack
 		pushw %dx			# save the BIOS boot device in
 						#  %dl for later
-		movw $(MEM_LDR_ENTRY/0x10), %ax # setup the
-		movw %ax, %ds			#  data segment
-		movl $welcome_msg, %si		# %ds:(%si) -> welcome message
+		movw %ax, %ds			# setup the
+		movw %ax, %es			#  data segments
+		movw $welcome_msg, %si		# %ds:(%si) -> welcome message
 		call putstr			# display the welcome message
 #
 # Setup the arguments that the loader is expecting from boot[12]
 #
-		movl $bootinfo_msg, %si		# %ds:(%si) -> boot args message
+		movw $bootinfo_msg, %si		# %ds:(%si) -> boot args message
 		call putstr			# display the message
-		pushw %ss			# Copy %ss
-		popw %es			#  to %es
-		movl $MEM_ARG, %ebx		# %es:(%ebx) -> boot args
+		movl $MEM_ARG, %ebx		# %ds:(%ebx) -> boot args
 		movw %bx, %di			# %es:(%di) -> boot args
 		xorl %eax, %eax			# zero %eax
 		movw $(MEM_ARG_SIZE/4), %cx	# Size of arguments in 32-bit
@@ -107,8 +95,9 @@ begin:		cld				# string ops inc
 		rep				# Clear the arguments
 		stosl				#  to zero
 		popw %dx			# restore BIOS boot device
-		movb %dl, %es:0x4(%ebx)		# set kargs->bootdev
-		orb $KARGS_FLAGS_CD, %es:0x8(%ebx) # kargs->bootflags |= KARGS_FLAGS_CD
+		movb %dl, 0x4(%ebx)		# set kargs->bootdev
+		orb $KARGS_FLAGS_CD, 0x8(%ebx)	# kargs->bootflags |=
+						#  KARGS_FLAGS_CD
 #
 # Turn on the A20 address line
 #
@@ -118,49 +107,61 @@ begin:		cld				# string ops inc
 #
 		movw $relocate_msg, %si		# Display the
 		call putstr			#  relocation message
-		movl $MEM_LOADER_ADDRESS, %edi	# %edi is the destination
-		movl $(MEM_LDR_ENTRY+end-start+MEM_AOUT_HEADER), %esi # %esi is 
-						#  the start of the raw loader
-		movl bi_file_length, %ecx	# Set %ecx to the length
-		subl $(end-start+MEM_AOUT_HEADER), %ecx	# of the raw loader
+		movl end+AOUT_ENTRY, %edi	# %edi is the destination
+		movl $(end+AOUT_HEADER), %esi	# %esi is 
+						#  the start of the text
+						#  segment
+		movl end+AOUT_TEXT, %ecx	# %ecx = length of the text
+						#  segment
 		lgdt gdtdesc			# setup our own gdt
 		cli				# turn off interrupts
 		movl %cr0, %eax			# Turn on
-		orl $0x1, %eax			#  protected
+		orb $0x1, %al			#  protected
 		movl %eax, %cr0			#  mode
 		.byte 0xea			# long jump to
-		.word MEM_LDR_ENTRY+pm_start	#   clear the instruction
-		.word SEL_SCODE			#   pre-fetch
+		.word pm_start			#   clear the instruction
+		.word SEL_SCODE			#   pre-fetch queue
 		.code32
 pm_start:	movw $SEL_SDATA, %ax		# Initialize
 		movw %ax, %ds			#  %ds and
 		movw %ax, %es			#  %es to a flat selector
-		rep				# Relocate
-		movsb				#  the loader
-		movl $MEM_BTX_IMAGE, %esi	# %esi -> BTX in the loader
+		rep				# Relocate the
+		movsb				#  text segment
+		addl $(MEM_PAGE_SIZE - 1), %edi	# pad %edi out to a new page
+		andl $~(MEM_PAGE_SIZE - 1), %edi #  for the data segment
+		movl end+AOUT_DATA, %ecx	# size of the data segment
+		rep				# Relocate the
+		movsb				#  data segment
+		movl end+AOUT_BSS, %ecx		# size of the bss
+		xorl %eax, %eax			# zero %eax
+		addb $3, %cl			# round %ecx up to
+		shrl $2, %ecx			#  a multiple of 4
+		rep				# zero the
+		stosl				#  bss
+		movl end+AOUT_ENTRY, %esi	# %esi -> relocated loader
+		addl $MEM_BTX_OFFSET, %esi	# %esi -> BTX in the loader
 		movl $MEM_BTX_ADDRESS, %edi	# %edi -> where BTX needs to go
 		movzwl 0xa(%esi), %ecx		# %ecx -> length of BTX
 		rep				# Relocate
 		movsb				#  BTX
-		ljmp $SEL_SCODE16,$(MEM_LDR_ENTRY+pm_16) # Jump to 16-bit PM
+		ljmp $SEL_SCODE16,$pm_16	# Jump to 16-bit PM
 		.code16
 pm_16:		movw $SEL_RDATA, %ax		# Initialize
 		movw %ax, %ds			#  %ds and
 		movw %ax, %es			#  %es to a real mode selector
 		movl %cr0, %eax			# Turn off
-		andl $~0x1, %eax		#  protected
+		andb $~0x1, %al			#  protected
 		movl %eax, %cr0			#  mode
 		.byte 0xea			# Long jump to
 		.word pm_end			#   clear the instruction
-		.word MEM_LDR_ENTRY/0x10	#   pre-fetch
+		.word 0x0			#   pre-fetch
 pm_end:		sti				# Turn interrupts back on now
 #
 # Copy the BTX client to MEM_BTX_CLIENT
 #
-		movw $(MEM_LDR_ENTRY/0x10), %ax # Initialize
-		movw %ax, %ds			#   %ds to local data segment
-		xorw %ax, %ax			# zero %ax and initialize
-		movw %ax, %es			#  %es to segment 0
+		xorw %ax, %ax			# zero %ax and set
+		movw %ax, %ds			#  %ds and %es
+		movw %ax, %es			#  to segment 0
 		movw $MEM_BTX_CLIENT, %di	# Prepare to relocate
 		movw $btx_client, %si		#  the simple btx client
 		movw $(btx_client_end-btx_client), %cx # length of btx client
@@ -170,17 +171,20 @@ pm_end:		sti				# Turn interrupts back on now
 # Copy the boot[12] args to where the BTX client can see them
 #
 		movw $MEM_ARG, %si		# where the args are at now
-		movw %ax, %ds			# need segment 0 in %ds
 		movw $MEM_ARG_BTX, %di		# where the args are moving to
 		movw $(MEM_ARG_SIZE/4), %cx	# size of the arguments in longs
 		rep				# Relocate
 		movsl				#  the words
 #
+# Save the entry point so the client can get to it later on
+#
+		movl end+AOUT_ENTRY, %eax	# load the entry point
+		stosl				# add it to the end of the
+						#  arguments
+#
 # Now we just start up BTX and let it do the rest
 #
-		movw $(MEM_LDR_ENTRY/0x10), %ax	# Initialize
-		movw %ax, %ds			#  %ds to the local data segment
-		movl $jump_message, %si		# Display the
+		movw $jump_message, %si		# Display the
 		call putstr			#  jump message
 		.byte 0xea			# Jump to
 		.word MEM_BTX_ENTRY 		# BTX entry
@@ -216,7 +220,7 @@ seta20.2:	inb $0x64,%al			# Get status
 		ret				# To caller
 
 #
-# BTX client to start btxld
+# BTX client to start btxldr
 #
 		.code32
 btx_client:	movl $(MEM_ARG_BTX-MEM_BTX_CLIENT+MEM_ARG_SIZE-4), %esi
@@ -228,7 +232,8 @@ push_arg:	lodsl				# Read argument
 		pushl %eax			# Push it onto the stack
 		loop push_arg			# Push all of the arguments
 		cld				# In case anyone depends on this
-		pushl $(MEM_LOADER_ADDRESS)	# Address to jump to
+		pushl MEM_ARG_BTX-MEM_BTX_CLIENT+MEM_ARG_SIZE # Entry point of
+						#  the loader
 		pushl %eax			# Emulate a near call
 		movl $0x1, %eax			# 'exec' system call
 		int $INT_SYS			# BTX system call
@@ -249,7 +254,7 @@ gdt.1:
 # Pseudo-descriptors.
 #
 gdtdesc:	.word gdt.1-gdt-1		# Limit
-		.long gdt+MEM_LDR_ENTRY		# Base
+		.long gdt			# Base
 		
 welcome_msg:	.asciz	"CD Loader 1.00\r\n\n"
 bootinfo_msg:	.asciz	"Building the boot loader arguments\r\n"