Due to space constraints, the UFS boot2 and boot1 use an evil hack where

boot2 calls back into boot1 to perform disk reads.  The ZFS MBR boot blocks
do not have the same space constraints, so remove this hack for ZFS.
While here, remove commented out code to support C/H/S addressing from
zfsldr.  The ZFS and GPT bootstraps always just use EDD LBA addressing.

MFC after:	2 weeks

4 files changed, 33 insertions, 129 deletions

diff --git a/sys/boot/i386/boot2/Makefile b/sys/boot/i386/boot2/Makefile
index d9b91df..64d49ec 100644
--- a/sys/boot/i386/boot2/Makefile
+++ b/sys/boot/i386/boot2/Makefile
@@ -32,6 +32,7 @@ CFLAGS=	-Os \
 	-mno-align-long-strings \
 	-mrtd \
 	-mregparm=3 \
+	-DUSE_XREAD \
 	-D${BOOT2_UFS} \
 	-DFLAGS=${BOOT_BOOT1_FLAGS} \
 	-DSIOPRT=${BOOT_COMCONSOLE_PORT} \
diff --git a/sys/boot/i386/common/drv.c b/sys/boot/i386/common/drv.c
index d249bc1..11f6628 100644
--- a/sys/boot/i386/common/drv.c
+++ b/sys/boot/i386/common/drv.c
@@ -26,7 +26,7 @@ __FBSDID("$FreeBSD$");
 #include "rbx.h"
 #include "util.h"
 #include "drv.h"
-#ifndef GPT
+#ifdef USE_XREAD
 #include "xreadorg.h"
 #endif
 
@@ -58,7 +58,7 @@ drvsize(struct dsk *dskp)
 }
 #endif	/* GPT */
 
-#ifdef GPT
+#ifndef USE_XREAD
 static struct {
 	uint16_t	len;
 	uint16_t	count;
@@ -66,7 +66,7 @@ static struct {
 	uint16_t	seg;
 	uint64_t	lba;
 } packet;
-#endif	/* GPT */
+#endif
 
 int
 drvread(struct dsk *dskp, void *buf, daddr_t lba, unsigned nblk)
@@ -75,7 +75,7 @@ drvread(struct dsk *dskp, void *buf, daddr_t lba, unsigned nblk)
 
 	if (!OPT_CHECK(RBX_QUIET))
 		printf("%c\b", c = c << 8 | c >> 24);
-#ifdef GPT
+#ifndef USE_XREAD
 	packet.len = 0x10;
 	packet.count = nblk;
 	packet.off = VTOPOFF(buf);
@@ -87,7 +87,7 @@ drvread(struct dsk *dskp, void *buf, daddr_t lba, unsigned nblk)
 	v86.edx = dskp->drive;
 	v86.ds = VTOPSEG(&packet);
 	v86.esi = VTOPOFF(&packet);
-#else	/* !GPT */
+#else	/* USE_XREAD */
 	v86.ctl = V86_ADDR | V86_CALLF | V86_FLAGS;
 	v86.addr = XREADORG;		/* call to xread in boot1 */
 	v86.es = VTOPSEG(buf);
@@ -95,7 +95,7 @@ drvread(struct dsk *dskp, void *buf, daddr_t lba, unsigned nblk)
 	v86.ebx = VTOPOFF(buf);
 	v86.ecx = lba >> 32;
 	v86.edx = nblk << 8 | dskp->drive;
-#endif	/* !GPT */
+#endif	/* USE_XREAD */
 	v86int();
 	if (V86_CY(v86.efl)) {
 		printf("%s: error %u lba %u\n",
diff --git a/sys/boot/i386/zfsboot/Makefile b/sys/boot/i386/zfsboot/Makefile
index 6f8f4f5..06ff863 100644
--- a/sys/boot/i386/zfsboot/Makefile
+++ b/sys/boot/i386/zfsboot/Makefile
@@ -6,9 +6,6 @@ FILES=		zfsboot
 
 NM?=		nm
 
-# A value of 0x80 enables LBA support.
-BOOT_BOOT1_FLAGS?=	0x80
-
 BOOT_COMCONSOLE_PORT?= 0x3f8
 BOOT_COMCONSOLE_SPEED?= 9600
 B2SIOFMT?=	0x3
@@ -25,7 +22,6 @@ CFLAGS=	-DBOOTPROG=\"zfsboot\" \
 	-mno-align-long-strings \
 	-mrtd \
 	-DBOOT2 \
-	-DFLAGS=${BOOT_BOOT1_FLAGS} \
 	-DSIOPRT=${BOOT_COMCONSOLE_PORT} \
 	-DSIOFMT=${B2SIOFMT} \
 	-DSIOSPD=${BOOT_COMCONSOLE_SPEED} \
@@ -64,8 +60,7 @@ zfsldr.out: zfsldr.o
 	${LD} ${LDFLAGS} -e start -Ttext ${ORG1} -o ${.TARGET} zfsldr.o
 
 CLEANFILES+=	zfsboot2 zfsboot.ld zfsboot.ldr zfsboot.bin zfsboot.out \
-		zfsboot.o zfsboot.s zfsboot.s.tmp xreadorg.h sio.o cons.o \
-		drv.o util.o
+		zfsboot.o zfsboot.s zfsboot.s.tmp sio.o cons.o drv.o util.o
 
 # We currently allow 65536 bytes for zfsboot - in practice it could be
 # any size up to 3.5Mb but keeping it fixed size simplifies zfsldr.
@@ -92,20 +87,13 @@ zfsboot.out: ${BTXCRT} zfsboot.o sio.o drv.o cons.o util.o
 
 zfsboot.o: zfsboot.s
 
-SRCS=	zfsboot.c xreadorg.h
+SRCS=	zfsboot.c
 
-zfsboot.s: zfsboot.c xreadorg.h ${.CURDIR}/../../zfs/zfsimpl.c
+zfsboot.s: zfsboot.c ${.CURDIR}/../../zfs/zfsimpl.c
 	${CC} ${CFLAGS} -S -o zfsboot.s.tmp ${.CURDIR}/zfsboot.c
 	sed -e '/align/d' -e '/nop/d' < zfsboot.s.tmp > zfsboot.s
 	rm -f zfsboot.s.tmp
 
-xreadorg.h: zfsldr.out
-	${NM} -t d ${.ALLSRC} | awk '/([0-9])+ T xread/ \
-	    { x = $$1 - ORG1; \
-	    printf("#define XREADORG %#x\n", REL1 + x) }' \
-	    ORG1=`printf "%d" ${ORG1}` \
-	    REL1=`printf "%d" ${REL1}` > ${.TARGET}
-
 .if ${MACHINE_CPUARCH} == "amd64"
 beforedepend zfsboot.s: machine
 CLEANFILES+=	machine
diff --git a/sys/boot/i386/zfsboot/zfsldr.S b/sys/boot/i386/zfsboot/zfsldr.S
index 7bcdfc4..182d88e 100644
--- a/sys/boot/i386/zfsboot/zfsldr.S
+++ b/sys/boot/i386/zfsboot/zfsldr.S
@@ -30,16 +30,12 @@
 		.set PRT_NUM,0x4		# Partitions
 		.set PRT_BSD,0xa5		# Partition type
 
-/* Flag Bits */
-		.set FL_PACKET,0x80		# Packet mode
-
 /* Misc. Constants */
 		.set SIZ_PAG,0x1000		# Page size
 		.set SIZ_SEC,0x200		# Sector size
 
 		.set NSECT,0x80
 		.globl start
-		.globl xread
 		.code16
 
 start:		jmp main			# Start recognizably
@@ -49,7 +45,7 @@ start:		jmp main			# Start recognizably
  * 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.
+ * written into our code, 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
@@ -80,34 +76,7 @@ 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:
- *
- * %ecx:%eax	- 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:	pushl %ecx			# Starting absolute block
-		pushl %eax			#  block 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,
+ * Load the rest of zfsboot2 and BTX up, copy the parts to the right locations,
  * and start it all up.
  */
 
@@ -181,7 +150,7 @@ main.4: 	xor %dx,%dx			# Partition:drive
  * itself to 0x9000 - doing it in this order means that none of the
  * memcpy regions overlap which would corrupt the copy.  Normally, BTX
  * clients start at MEM_USR, or 0xa000, but when we use btxld to
- * create boot2, we use an entry point of 0x2000.  That entry point is
+ * create zfsboot2, we use an entry point of 0x2000.  That entry point is
  * relative to MEM_USR; thus boot2.bin starts at 0xc000.
  *
  * The load area and the target area for the client overlap so we have
@@ -241,15 +210,29 @@ seta20.3:	sti				# Enable interrupts
 
 
 /*
- * Trampoline used to call read from within boot1.
+ * Trampoline used to call read from within zfsldr.  Sets up an EDD
+ * packet on the stack and passes it to read.
+ *
+ * %eax		- int     - LBA to read in relative to partition start
+ * %dl		- byte    - drive to read from
+ * %dh		- byte    - num sectors to read
+ * %si		- ptr     - MBR partition entry
  */
 nread:		xor %eax,%eax			# Sector offset in partition
-nread.1:	mov $MEM_BUF,%bx		# Transfer buffer
-		xor %ecx,%ecx			# Get
+nread.1:	xor %ecx,%ecx			# Get
 		addl 0x8(%si),%eax		#  LBA
 		adc $0,%ecx
-		push %cs			# Read from
-		callw xread.1	 		#  disk
+		pushl %ecx			# Starting absolute block
+		pushl %eax			#  block number
+		push %es			# Address of
+		push $MEM_BUF			#  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
 		jnc return			# If success, return
 		mov $msg_read,%si		# Otherwise, set the error
 						#  message and fall through to
@@ -293,9 +276,7 @@ return: 	retw				# To caller
  * %dl	- byte     - drive number
  * stack - 10 bytes - EDD Packet
  */
-read:		testb $FL_PACKET,%cs:MEM_REL+flags-start # LBA support enabled?
-		jz read.1			# No, use CHS
-		cmpb $0x80,%dl			# Hard drive?
+read:		cmpb $0x80,%dl			# Hard drive?
 		jb read.1			# No, use CHS
 		mov $0x55aa,%bx			# Magic
 		push %dx			# Save
@@ -311,73 +292,9 @@ read:		testb $FL_PACKET,%cs:MEM_REL+flags-start # LBA support enabled?
 		movb $0x42,%ah			# BIOS: Extended
 		int $0x13			#  read
 		retw				# To caller
-#if 0	
-read.1:	 	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 ereturn			# No, return an error
-		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
-#ifdef	TRACK_AT_A_TIME
-		movb %ah,%al			#  track
-#else
-		movb $1,%al			#  one sector
-#endif
-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.1			# If not done
-read.6: 	retw				# To caller
-#else
 read.1:		mov $msg_chs,%si
 		jmp error
 msg_chs:	.asciz "CHS not supported"
-#endif
 
 /* Messages */
 
@@ -386,8 +303,6 @@ msg_part:	.asciz "Boot"
 
 prompt: 	.asciz " error\r\n"
 
-flags:		.byte FLAGS			# Flags
-
 		.org PRT_OFF,0x90
 
 /* Partition table */