diff options
| -rw-r--r-- | sys/boot/i386/boot0/Makefile | 24 | ||||
| -rw-r--r-- | sys/boot/i386/boot0/boot0.s | 224 |
2 files changed, 82 insertions, 166 deletions
diff --git a/sys/boot/i386/boot0/Makefile b/sys/boot/i386/boot0/Makefile index 429a62c..4d3f006 100644 --- a/sys/boot/i386/boot0/Makefile +++ b/sys/boot/i386/boot0/Makefile @@ -10,33 +10,23 @@ BINMODE= 444 M4?= m4 -# The default set of flags compiled into boot0. This enables update (writing -# the modified boot0 back to disk after running so that the selection made is -# saved), packet mode (detect and use the BIOS EDD extensions if we try to -# boot past the 1024 cylinder liimt), and booting from all valid slices. -BOOT_BOOT0_FLAGS?= 0x8f +B0FLAGS=0xf +B0TICKS=0xb6 -# The number of timer ticks to wait for a keypress before assuming the default -# selection. Since there are 18.2 ticks per second, the default value of -# 0xb6 (182d) corresponds to 10 seconds. -BOOT_BOOT0_TICKS?= 0xb6 - -# The base address that we the boot0 code to to run it. Don't change this -# unless you are glutton for punishment. -BOOT_BOOT0_ORG?= 0x600 +ORG= 0x600 boot0: boot0.o .if ${OBJFORMAT} == aout - ${LD} -N -s -T ${BOOT_BOOT0_ORG} -o boot0.out boot0.o + ${LD} -N -s -T ${ORG} -o boot0.out boot0.o dd if=boot0.out of=${.TARGET} ibs=32 skip=1 .else - ${LD} -N -e start -Ttext ${BOOT_BOOT0_ORG} -o boot0.out boot0.o + ${LD} -N -e start -Ttext ${ORG} -o boot0.out boot0.o objcopy -S -O binary boot0.out ${.TARGET} .endif boot0.o: boot0.s - ${AS} ${AFLAGS} --defsym FLAGS=${BOOT_BOOT0_FLAGS} \ - --defsym TICKS=${BOOT_BOOT0_TICKS} ${.IMPSRC} -o ${.TARGET} + ${AS} ${AFLAGS} --defsym FLAGS=${B0FLAGS} --defsym TICKS=${B0TICKS} \ + ${.IMPSRC} -o ${.TARGET} CLEANFILES+= boot0.out boot0.o diff --git a/sys/boot/i386/boot0/boot0.s b/sys/boot/i386/boot0/boot0.s index 90c0e5c..5c2eca2 100644 --- a/sys/boot/i386/boot0/boot0.s +++ b/sys/boot/i386/boot0/boot0.s @@ -15,20 +15,17 @@ # $FreeBSD$ -# A 1024-byte boot manager. +# A 512-byte boot manager. .set NHRDRV,0x475 # Number of hard drives .set ORIGIN,0x600 # Execution address - .set SECTOR_SIZE,0x200 # Length of a sector - .set NUM_SECTORS,2 # Total length in sectors - - .set FAKE,ORIGIN+(SECTOR_SIZE*NUM_SECTORS) # Partition entry + .set FAKE,0x800 # Partition entry .set LOAD,0x7c00 # Load address .set PRT_OFF,0x1be # Partition table - .set TBL0SZ,table0_end-table0 # Table 0 size - .set TBL1SZ,table1_end-table1 # Table 1 size + .set TBL0SZ,0x3 # Table 0 size + .set TBL1SZ,0xc # Table 1 size .set MAGIC,0xaa55 # Magic: bootable @@ -36,21 +33,14 @@ .set KEY_F1,0x3b # F1 key scan code # -# Flag bits -# - .set FL_PACKET,0x80 # Packet mode - .set FL_NOUPDATE,0x40 # Don't save selection - .set FL_SETDRV,0x20 # Override drive number -# # Addresses in the sector of embedded data values. -# Accessed with negative offsets from the end of the relocated sectors (%bp). -# - .set _PRT_END,(FAKE-(ORIGIN+SECTOR_SIZE)) - .set _NXTDRV,-(_PRT_END+0x48) # Next drive - .set _OPT,-(_PRT_END+0x47) # Default option - .set _SETDRV,-(_PRT_END+0x46) # Drive to force - .set _FLAGS,-(_PRT_END+0x45) # Flags - .set _TICKS,-(_PRT_END+0x44) # Timeout ticks +# Accessed with negative offsets from the end of the relocated sector (%ebp). +# + .set _NXTDRV,-0x48 # Next drive + .set _OPT,-0x47 # Default option + .set _SETDRV,-0x46 # Drive to force + .set _FLAGS,-0x45 # Flags + .set _TICKS,-0x44 # Timeout ticks .set _FAKE,0x0 # Fake partition entry .set _MNUOPT,0xc # Menu options @@ -62,48 +52,40 @@ # segments start at 0. # The stack is immediately below the address we were loaded to. # -# Note that this section of code is used as the first signature check in -# boot0cfg(8). -# start: cld # String ops inc xorw %ax,%ax # Zero movw %ax,%es # Address movw %ax,%ds # data movw %ax,%ss # Set up movw $LOAD,%sp # stack -# -# End signature code -# + +# +# Copy this code to the address it was linked for +# + movw %sp,%si # Source + movw $start,%di # Destination + movw $0x100,%cx # Word count + rep # Relocate + movsw # code # # Set address for variable space beyond code, and clear it. # Notice that this is also used to point to the values embedded in the block, # by using negative offsets. # - movw $fake,%bp # Address variables - movw %bp,%di # %di used in stosw - movw $0x8,%cx # Words to clear + movw %di,%bp # Address variables + movb $0x8,%cl # Words to clear rep # Zero stosw # them - incb -0xe(%di) # Sector number 1 -# -# Reload all of boot0 (including the extra sectors) into memory at the -# relocation address. -# - push %dx # Save drive number - movw $start,%bx # Origin we were linked for - movw %bp,%si # Fake PTE - movw $0x200+NUM_SECTORS,%ax # Read in all - callw intx13 # of boot0 - pop %dx # Restore # # Relocate to the new copy of the code. # - jmp main+ORIGIN-LOAD # To relocated code + incb -0xe(%di) # Sector number + jmp main-LOAD+ORIGIN # To relocated code # -# Check what flags were loaded with us; specifically, use a predefined Drive. +# Check what flags were loaded with us, specifically, Use a predefined Drive. # If what the bios gives us is bad, use the '0' in the block instead, as well. # -main: testb $FL_SETDRV,_FLAGS(%bp) # Set number drive? +main: testb $0x20,_FLAGS(%bp) # Set number drive? jnz main.1 # Yes testb %dl,%dl # Drive number valid? js main.2 # Possibly (0x80 set) @@ -151,7 +133,7 @@ main.3: movb %ch,-0x4(%bx) # Zero active flag (ch == 0) jne main.4 # No # # If it matches get the matching element in the -# next array. If it doesn't, we are already +# next array. if it doesn't, we are already # pointing at its first element which points to a "?". # addw $TBL1SZ,%di # Adjust @@ -192,7 +174,7 @@ main.6: addb $'0'|0x80,%al # Save next callw putx # item # # Now that we've printed the drive (if we needed to), display a prompt. -# Get ready for the input by noting the time. +# Get ready for the input byt noting the time. # main.7: movw $prompt,%si # Display callw putstr # prompt @@ -260,7 +242,7 @@ main.12: cbtw # Option # for rewriting to the disk. # movb %al,_OPT(%bp) # Save option - movw $fake,%si # Partition for write + movw $FAKE,%si # Partition for write movb (%si),%dl # Drive number movw %si,%bx # Partition for read cmpb $0x4,%al # F5 pressed? @@ -274,10 +256,10 @@ main.12: cbtw # Option # If not asked to do a write-back (flags 0x40) don't do one. # main.13: pushw %bx # Save - testb $FL_NOUPDATE,_FLAGS(%bp) # Skip update? + testb $0x40,_FLAGS(%bp) # No updates? jnz main.14 # Yes movw $start,%bx # Data to write - movw $0x301,%ax # Write 1 sector + movb $0x3,%ah # Write sector callw intx13 # to disk main.14: popw %si # Restore popf # Restore @@ -292,16 +274,19 @@ main.14: popw %si # Restore # load selected bootsector to the LOAD location in RAM. # If it fails to read or isn't marked bootable, treat it # as a bad selection. +# XXX what does %si carry? # main.15: movw $LOAD,%bx # Address for read - movw $0x201,%ax # Read 1 sector + movb $0x2,%ah # Read sector callw intx13 # from disk jc main.10 # If error cmpw $MAGIC,0x1fe(%bx) # Bootable? jne main.10 # No - callw putn # Leave some space + pushw %si # Save + movw $crlf,%si # Leave some + callw puts # space + popw %si # Restore jmp *%bx # Invoke bootstrap - # # Display routines # @@ -340,91 +325,28 @@ putchr: pushw %bx # Save retw # To caller # One-sector disk I/O routine -# -# Calling conventions: (assumes %si -> partition table entry) -# -# 0x1(%si) - byte - head -# 0x2(%si) - word - cylinder/sector -# 0x8(%si) - long - LBA to use if needed -# %ah - byte - operation, 2 = read, 3 = write -# %al - byte - sector count -# %dl - byte - drive number -# %es:(%bx) - void - buffer to use for transfer -# -# If the head == 0xff, and cylinder/sector == 0xffff, then try -# to use the EDD stuff with the LBA offset instead of CHS. However, -# use CHS if at all possible. intx13: movb 0x1(%si),%dh # Load head movw 0x2(%si),%cx # Load cylinder:sector + movb $0x1,%al # Sector count pushw %si # Save movw %sp,%di # Save - cmpb $0xff,%dh # Might we need LBA? - jne intx13.2 # No, just use CHS - cmpw $0xffff,%cx # Do we need LBA? - jne intx13.2 # No - testb $FL_PACKET,_FLAGS(%bp) # Try the packet interface? - jz intx13.2 # No - pushw %cx # Save - pushw %bx # Save - movw $0x55aa,%bx # Magic - pushw %ax # Save - movb $0x41,%ah # BIOS: EDD extensions - int $0x13 # present? - popw %ax # Restore - jc intx13.1 # Not present, use CHS - cmpw $0xaa55,%bx # Magic? - jne intx13.1 # Not present, use CHS - testb $0x1,%cl # Packet mode available? - jz intx13.1 # No, use CHS - orb $0x40,%ah # Use disk packet -intx13.1: popw %bx # Restore - popw %cx # Restore - testb $0x40,%ah # Using packet mode? - jz intx13.2 # No, so skip the rest + testb $0x80,_FLAGS(%bp) # Use packet interface? + jz intx13.1 # No pushl $0x0 # Set the pushl 0x8(%si) # LBA address pushw %es # Set the transfer pushw %bx # buffer address - push $0x0 # Punch a hole in the stack - push $0x10 # Packet size + push $0x1 # Block count + push $0x10 # Packet size movw %sp,%si # Packet pointer - xchgb %al,0x2(%si) # Set the block count in the - # packet and zero %al, - # turning verify off for writes -intx13.2: int $0x13 # BIOS: Disk I/O + decw %ax # Verify off + orb $0x40,%ah # Use disk packet +intx13.1: int $0x13 # BIOS: Disk I/O movw %di,%sp # Restore popw %si # Restore retw # To caller - .org PRT_OFF-0xe,0x90 -# -# These values are sometimes changed before writing back to the drive -# Be especially careful that nxtdrv: must come after drive:, as it -# is part of the same string. -# -# Note that the 'drive' string variable is used as the second signature -# check in boot0cfg(8). -# -version_minor: .byte 0x1 # minor version -version_major: .byte 0x1 # major version -drive: .ascii "Drive " -nxtdrv: .byte 0x0 # Next drive number -opt: .byte 0x0 # Option -setdrv: .byte 0x80 # Drive to force -flags: .byte FLAGS # Flags -ticks: .word TICKS # Delay - -# -# here is the 64 byte partition table that fdisk would fiddle with. -# -partbl: .fill 0x40,0x1,0x0 # Partition table - .word MAGIC # Magic number - -# -# start of sector two.. ugh -# - .org SECTOR_SIZE,0x90 # Menu strings item: .ascii " "; .byte ' '|0x80 @@ -437,14 +359,12 @@ tables: # # These entries identify invalid or NON BOOT types and partitions. # -table0: .byte 0x0, 0x5, 0xf -table0_end: + .byte 0x0, 0x5, 0xf # # These values indicate bootable types we know the names of # -table1: .byte 0x1, 0x4, 0x6, 0x7, 0xb, 0xc, 0xe, 0x63, 0x83 + .byte 0x1, 0x4, 0x6, 0xb, 0xc, 0xe, 0x63, 0x83 .byte 0x9f, 0xa5, 0xa6, 0xa9 -table1_end: # # These are offsets that match the known names above and point to the strings # that will be printed. @@ -453,35 +373,41 @@ table1_end: .byte os_dos-. # DOS .byte os_dos-. # DOS .byte os_dos-. # DOS - .byte os_nt-. # NT or OS/2 - .byte os_windows-. # Windows - .byte os_windows-. # Windows - .byte os_windows-. # Windows + .byte os_dos-. # Windows + .byte os_dos-. # Windows + .byte os_dos-. # Windows .byte os_unix-. # UNIX .byte os_linux-. # Linux - .byte os_bsdos-. # BSD/OS + .byte os_bsd-. # BSD/OS .byte os_freebsd-. # FreeBSD - .byte os_openbsd-. # OpenBSD - .byte os_netbsd-. # NetBSD + .byte os_bsd-. # OpenBSD + .byte os_bsd-. # NetBSD # # And here are the strings themselves. 0x80 or'd into a byte indicates # the end of the string. (not so great for Russians but...) # -os_misc: .ascii "Unknow"; .byte 'n'|0x80 -os_dos: .ascii "DO"; .byte 'S'|0x80 -os_nt: .ascii "Windows N"; .byte 'T'|0x80 -os_windows: .ascii "Window"; .byte 's'|0x80 -os_unix: .ascii "UNI"; .byte 'X'|0x80 -os_linux: .ascii "Linu"; .byte 'x'|0x80 -os_freebsd: .ascii "FreeBS"; .byte 'D'|0x80 -os_openbsd: .ascii "OpenBS"; .byte 'D'|0x80 -os_netbsd: .ascii "NetBS"; .byte 'D'|0x80 -os_bsdos: .ascii "BSD/O"; .byte 'S'|0x80 +os_misc: .ascii "?"; .byte '?'|0x80 +os_dos: .ascii "DO"; .byte 'S'|0x80 +os_unix: .ascii "UNI"; .byte 'X'|0x80 +os_linux: .ascii "Linu"; .byte 'x'|0x80 +os_freebsd: .ascii "Free" +os_bsd: .ascii "BS"; .byte 'D'|0x80 + .org PRT_OFF-0xc,0x90 # -# Fake partition entry created at the end of the table used when loading -# boot0 at the very beginning and when loading an MBR from another disk when -# F5 is pressed. +# These values are sometimes changed before writing back to the drive +# Be especially careful that nxtdrv: must come after drive:, as it +# is part of the same string. # - .org SECTOR_SIZE*NUM_SECTORS, 0x0 -fake: +drive: .ascii "Drive " +nxtdrv: .byte 0x0 # Next drive number +opt: .byte 0x0 # Option +setdrv: .byte 0x80 # Drive to force +flags: .byte FLAGS # Flags +ticks: .word TICKS # Delay + +# +# here is the 64 byte partition table that fdisk would fiddle with. +# +partbl: .fill 0x40,0x1,0x0 # Partition table + .word MAGIC # Magic number |
