svn commit: r223597 - head/sys/boot/i386/zfsboot
John Baldwin
jhb at FreeBSD.org
Mon Jun 27 13:58:25 UTC 2011
Author: jhb
Date: Mon Jun 27 13:58:24 2011
New Revision: 223597
URL: http://svn.freebsd.org/changeset/base/223597
Log:
- Remove the fake BPB from zfsldr. zfsldr doesn't support booting from
floppies, so it will not be used as the start of an emulated floppy
image on a bootable CD which is what the fake BPB was used for.
- Only check that EDD packet mode is available once at the start of
zfsldr rather than for each disk sector now that we read data in one
sector at a time. As a result, collapse the remaining bits of read
up into nread and rename nread to read.
- Restore a return at the end of putstr that I removed in the previous
revision.
Tested by: Henri Hennebert (earlier version)
MFC after: 1 week
Modified:
head/sys/boot/i386/zfsboot/Makefile
head/sys/boot/i386/zfsboot/zfsldr.S
Modified: head/sys/boot/i386/zfsboot/Makefile
==============================================================================
--- head/sys/boot/i386/zfsboot/Makefile Mon Jun 27 13:23:51 2011 (r223596)
+++ head/sys/boot/i386/zfsboot/Makefile Mon Jun 27 13:58:24 2011 (r223597)
@@ -57,7 +57,7 @@ zfsboot1: zfsldr.out
objcopy -S -O binary zfsldr.out ${.TARGET}
zfsldr.out: zfsldr.o
- ${LD} ${LDFLAGS} -e start -Ttext ${ORG1} -o ${.TARGET} zfsldr.o
+ ${LD} ${LDFLAGS} -e main -Ttext ${ORG1} -o ${.TARGET} zfsldr.o
CLEANFILES+= zfsboot2 zfsboot.ld zfsboot.ldr zfsboot.bin zfsboot.out \
zfsboot.o zfsboot.s zfsboot.s.tmp sio.o cons.o drv.o util.o
Modified: head/sys/boot/i386/zfsboot/zfsldr.S
==============================================================================
--- head/sys/boot/i386/zfsboot/zfsldr.S Mon Jun 27 13:23:51 2011 (r223596)
+++ head/sys/boot/i386/zfsboot/zfsldr.S Mon Jun 27 13:58:24 2011 (r223597)
@@ -34,46 +34,9 @@
.set SIZ_SEC,0x200 # Sector size
.set NSECT,0x80
- .globl start
+ .globl main
.code16
-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 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
- * 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
-
- .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
-
- .org 0x24, 0x00
-ebpb: .byte 0 # BIOS physical drive number (W)
-
- .org 0x25,0x90
/*
* Load the rest of zfsboot2 and BTX up, copy the parts to the right locations,
* and start it all up.
@@ -90,18 +53,17 @@ main: cld # String ops inc
mov %cx,%ss # Set up
mov $start,%sp # stack
/*
- * 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.
+ * 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 read.
+ * 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.
*/
+ call check_edd # Make sure EDD works
mov $part4,%si # Dummy partition
- cmpb $0x80,%dl # Hard drive?
- jb main.4 # No
xor %eax,%eax # Read MBR
movl $MEM_BUF,%ebx # from first
- callw nread # sector
+ call read # sector
mov $0x1,%cx # Two passes
main.1: mov $MEM_BUF+PRT_OFF,%si # Partition table
movb $0x1,%dh # Partition
@@ -122,10 +84,6 @@ main.3: add $0x10,%si # Next entry
*/
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
@@ -153,7 +111,7 @@ main.5: mov %dx,MEM_ARG # Save args
movl $1024,%eax # Offset to boot2
mov $MEM_BTX,%ebx # Destination buffer
main.6: pushal # Save params
- callw nread # Read disk
+ call read # Read disk
popal # Restore
incl %eax # Advance to
add $SIZ_SEC,%ebx # next sector
@@ -200,16 +158,16 @@ seta20.3: sti # Enable interrupts
/*
- * Trampoline used to call read from within zfsldr. Sets up an EDD
- * packet on the stack and passes it to read. We assume that the
- * destination address is always segment-aligned.
+ * Read a sector from the disk. Sets up an EDD packet on the stack
+ * and passes it to read. We assume that the destination address is
+ * always segment-aligned.
*
* %eax - int - LBA to read in relative to partition start
* %ebx - ptr - destination address
* %dl - byte - drive to read from
* %si - ptr - MBR partition entry
*/
-nread: xor %ecx,%ecx # Get
+read: xor %ecx,%ecx # Get
addl 0x8(%si),%eax # LBA
adc $0,%ecx
pushl %ecx # Starting absolute block
@@ -219,12 +177,13 @@ nread: xor %ecx,%ecx # Get
push $0 # transfer buffer
push $0x1 # Read 1 sector
push $0x10 # Size of packet
- mov %sp,%bp # Packet pointer
- callw read # Read from disk
- jc nread.1 # If error, fail
- lea 0x10(%bp),%sp # Clear stack
+ mov %sp,%si # Packet pointer
+ mov $0x42,%ah # BIOS: Extended
+ int $0x13 # read
+ jc read.1 # If error, fail
+ lea 0x10(%si),%sp # Clear stack
ret # If success, return
-nread.1: mov %ah,%al # Format
+read.1: mov %ah,%al # Format
mov $read_err,%di # error
call hex8 # code
mov $msg_read,%si # Set the error message and
@@ -250,36 +209,26 @@ putstr.0: mov $0x7,%bx # Page:attribu
putstr: lodsb # Get char
testb %al,%al # End of string?
jne putstr.0 # No
-
+ ret # 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
+ * Check to see if the disk supports EDD. zfsboot requires EDD and does not
+ * support older C/H/S disk I/O.
*/
-read: cmpb $0x80,%dl # Hard drive?
- jb read.1 # No, use CHS
+check_edd: cmpb $0x80,%dl # Hard drive?
+ jb check_edd.1 # No, fail to boot
mov $0x55aa,%bx # Magic
push %dx # Save
movb $0x41,%ah # BIOS: Check
int $0x13 # extensions present
pop %dx # Restore
- jc read.1 # If error, use CHS
+ jc check_edd.1 # If error, fail
cmp $0xaa55,%bx # Magic?
- jne read.1 # No, so use CHS
+ jne check_edd.1 # No, so fail
testb $0x1,%cl # Packet interface?
- jz read.1 # No, so use CHS
- mov %bp,%si # Disk packet
- movb $0x42,%ah # BIOS: Extended
- int $0x13 # read
- retw # To caller
-read.1: mov $msg_chs,%si
- jmp error
-
+ jz check_edd.1 # No, so fail
+ ret # EDD ok, keep booting
+check_edd.1: mov $msg_chs,%si # Warn that CHS is
+ jmp error # unsupported and fail
/*
* AL to hex, saving the result to [EDI].
*/
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