mirror of
https://git.FreeBSD.org/src.git
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The new and improved boot0, v1.1. This version adds the following:
- Autodetection and support of the BIOS EDD extensions to work around the 1024 cylinder limit on all but really ancient BIOS's. - To work around some BIOS's which break when EDD is used with older drives, we only attempt to use EDD if the cylinder is > 1023. - Since this new code required more space than we had left, expand boot0 to 2 sectors (1024 bytes) in length. - Add support for boot0 being multiple sectors using predefined constants. If boot0 needs to be extended in the future, all that is required is bumping the NUM_SECTORS constant. - Now that we have more room to work with, add a few more fs type descriptions while making others more verbose.
This commit is contained in:
John Baldwin
parent
fcb7c05133
commit
1dce5cb37f
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=63032
@ -8,7 +8,8 @@ BINMODE= 444
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M4?= m4
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B0FLAGS=0xf
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# update, packet mode, and all slices enabled by default
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B0FLAGS=0x8f
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B0TICKS=0xb6
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ORG= 0x600
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@ -15,17 +15,20 @@
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# $FreeBSD$
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# A 512-byte boot manager.
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# A 1024-byte boot manager.
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.set NHRDRV,0x475 # Number of hard drives
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.set ORIGIN,0x600 # Execution address
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.set FAKE,0x800 # Partition entry
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.set SECTOR_SIZE,0x200 # Length of a sector
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.set NUM_SECTORS,2 # Total length in sectors
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.set FAKE,ORIGIN+(SECTOR_SIZE*NUM_SECTORS) # Partition entry
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.set LOAD,0x7c00 # Load address
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.set PRT_OFF,0x1be # Partition table
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.set TBL0SZ,0x3 # Table 0 size
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.set TBL1SZ,0xb # Table 1 size
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.set TBL0SZ,table0_end-table0 # Table 0 size
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.set TBL1SZ,table1_end-table1 # Table 1 size
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.set MAGIC,0xaa55 # Magic: bootable
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@ -33,14 +36,21 @@
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.set KEY_F1,0x3b # F1 key scan code
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#
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# Addresses in the sector of embedded data values.
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# Accessed with negative offsets from the end of the relocated sector (%ebp).
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# Flag bits
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#
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.set _NXTDRV,-0x48 # Next drive
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.set _OPT,-0x47 # Default option
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.set _SETDRV,-0x46 # Drive to force
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.set _FLAGS,-0x45 # Flags
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.set _TICKS,-0x44 # Timeout ticks
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.set FL_PACKET,0x80 # Packet mode
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.set FL_NOUPDATE,0x40 # Don't save selection
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.set FL_SETDRV,0x20 # Override drive number
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#
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# Addresses in the sector of embedded data values.
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# Accessed with negative offsets from the end of the relocated sectors (%bp).
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#
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.set _PRT_END,(FAKE-(ORIGIN+SECTOR_SIZE))
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.set _NXTDRV,-(_PRT_END+0x48) # Next drive
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.set _OPT,-(_PRT_END+0x47) # Default option
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.set _SETDRV,-(_PRT_END+0x46) # Drive to force
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.set _FLAGS,-(_PRT_END+0x45) # Flags
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.set _TICKS,-(_PRT_END+0x44) # Timeout ticks
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.set _FAKE,0x0 # Fake partition entry
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.set _MNUOPT,0xc # Menu options
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@ -52,40 +62,48 @@
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# segments start at 0.
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# The stack is immediatly below the address we were loaded to.
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#
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# Note that this section of code is used as the first signature check in
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# boot0cfg(8).
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#
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start: cld # String ops inc
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xorw %ax,%ax # Zero
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movw %ax,%es # Address
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movw %ax,%ds # data
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movw %ax,%ss # Set up
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movw $LOAD,%sp # stack
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#
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# Copy this code to the address it was linked for
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#
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movw %sp,%si # Source
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movw $start,%di # Destination
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movw $0x100,%cx # Word count
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rep # Relocate
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movsw # code
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#
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# End signature code
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#
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#
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# Set address for variable space beyond code, and clear it.
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# Notice that this is also used to point to the values embedded in in the block,
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# by using negative offsets.
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#
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movw %di,%bp # Address variables
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movw $fake,%bp # Address variables
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movw %bp,%di # %di used in stosw
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movb $0x8,%cl # Words to clear
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rep # Zero
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stosw # them
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incb -0xe(%di) # Sector number 1
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#
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# Reload all of boot0 (including the extra sectors) into memory at the
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# relocation address.
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#
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push %dx # Save drive number
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movw $start,%bx # Origin we were linked for
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movw %bp,%si # Fake PTE
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movw $0x200+NUM_SECTORS,%ax # Read in all
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callw intx13 # of boot0
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pop %dx # Restore
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#
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# Relocate to the new copy of the code.
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#
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incb -0xe(%di) # Sector number
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jmp main-LOAD+ORIGIN # To relocated code
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jmp main+ORIGIN-LOAD # To relocated code
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#
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# Check what flags were loaded with us, specifically, Use a predefined Drive.
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# Check what flags were loaded with us; specifically, use a predefined Drive.
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# If what the bios gives us is bad, use the '0' in the block instead, as well.
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#
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main: testb $0x20,_FLAGS(%bp) # Set number drive?
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main: testb $FL_SETDRV,_FLAGS(%bp) # Set number drive?
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jnz main.1 # Yes
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testb %dl,%dl # Drive number valid?
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js main.2 # Possibly (0x80 set)
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@ -133,7 +151,7 @@ main.3: movb %ch,-0x4(%bx) # Zero active flag (ch == 0)
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jne main.4 # No
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#
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# If it matches get the matching element in the
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# next array. if it doesn't, we are already
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# next array. If it doesn't, we are already
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# pointing at its first element which points to a "?".
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#
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addw $TBL1SZ,%di # Adjust
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@ -174,7 +192,7 @@ main.6: addb $'0'|0x80,%al # Save next
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callw putx # item
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#
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# Now that we've printed the drive (if we needed to), display a prompt.
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# Get ready for the input byt noting the time.
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# Get ready for the input by noting the time.
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#
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main.7: movw $prompt,%si # Display
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callw putstr # prompt
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@ -242,7 +260,7 @@ main.12: cbtw # Option
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# for rewriting to the disk.
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#
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movb %al,_OPT(%bp) # Save option
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movw $FAKE,%si # Partition for write
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movw $fake,%si # Partition for write
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movb (%si),%dl # Drive number
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movw %si,%bx # Partition for read
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cmpb $0x4,%al # F5 pressed?
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@ -256,10 +274,10 @@ main.12: cbtw # Option
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# If not asked to do a write-back (flags 0x40) don't do one.
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#
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main.13: pushw %bx # Save
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testb $0x40,_FLAGS(%bp) # No updates?
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testb $FL_NOUPDATE,_FLAGS(%bp) # Skip update?
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jnz main.14 # Yes
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movw $start,%bx # Data to write
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movb $0x3,%ah # Write sector
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movw $0x301,%ax # Write 1 sector
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callw intx13 # to disk
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main.14: popw %si # Restore
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popf # Restore
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@ -274,19 +292,22 @@ main.14: popw %si # Restore
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# load selected bootsector to the LOAD location in RAM.
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# If it fails to read or isn't marked bootable, treat it
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# as a bad selection.
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# XXX what does %si carry?
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#
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main.15: movw $LOAD,%bx # Address for read
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movb $0x2,%ah # Read sector
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movw $0x201,%ax # Read 1 sector
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callw intx13 # from disk
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jc main.10 # If error
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cmpw $MAGIC,0x1fe(%bx) # Bootable?
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jne main.10 # No
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pushw %si # Save
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movw $crlf,%si # Leave some
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callw puts # space
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popw %si # Restore
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callw putn # Leave some space
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jmp *%bx # Invoke bootstrap
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/*
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movw %bx,%si # Memory to dump
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movw $SECTOR_SIZE/16,%dx # Lines to display
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callw memdump # Dump memory
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hang: jmp hang # Spin
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*/
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#
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# Display routines
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#
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@ -325,79 +346,74 @@ putchr: pushw %bx # Save
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retw # To caller
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# One-sector disk I/O routine
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#
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# Calling conventions: (assumes %si -> partition table entry)
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#
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# 0x1(%si) - byte - head
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# 0x2(%si) - word - cylinder/sector
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# 0x8(%si) - long - LBA to use if needed
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# %ah - byte - operation, 2 = read, 3 = write
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# %al - byte - sector count
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# %dl - byte - drive number
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# %es:(%bx) - void - buffer to use for transfer
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#
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# If the head == 0xff, and cylinder/sector == 0xffff, then try
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# to use the EDD stuff with the LBA offset instead of CHS. However,
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# use CHS if at all possible.
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intx13: movb 0x1(%si),%dh # Load head
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movw 0x2(%si),%cx # Load cylinder:sector
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movb $0x1,%al # Sector count
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pushw %si # Save
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movw %sp,%di # Save
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testb $0x80,_FLAGS(%bp) # Use packet interface?
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jz intx13.1 # No
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cmpb $0xff,%dh # Might we need LBA?
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jne intx13.2 # No, just use CHS
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cmpw $0xffff,%cx # Do we need LBA?
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jne intx13.2 # No
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testb $FL_PACKET,_FLAGS(%bp) # Try the packet interface?
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jz intx13.2 # No
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pushw %cx # Save
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pushw %bx # Save
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movw $0x55aa,%bx # Magic
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pushw %ax # Save
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movb $0x41,%ah # BIOS: EDD extensions
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int $0x13 # present?
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popw %ax # Restore
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jc intx13.1 # Not present, use CHS
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cmpw $0xaa55,%bx # Magic?
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jne intx13.1 # Not present, use CHS
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testb $0x1,%cl # Packet mode available?
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jz intx13.1 # No, use CHS
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orb $0x40,%ah # Use disk packet
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intx13.1: popw %bx # Restore
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popw %cx # Restore
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testb $0x40,%ah # Using packet mode?
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jz intx13.2 # No, so skip the rest
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pushl $0x0 # Set the
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pushl 0x8(%si) # LBA address
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pushw %es # Set the transfer
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pushw %bx # buffer address
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push $0x1 # Block count
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push $0x10 # Packet size
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push $0x0 # Punch a hole in the stack
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push $0x10 # Packet size
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movw %sp,%si # Packet pointer
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decw %ax # Verify off
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orb $0x40,%ah # Use disk packet
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intx13.1: int $0x13 # BIOS: Disk I/O
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xchgb %al,0x2(%si) # Set the block count in the
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# packet and zero %al,
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# turning verify off for writes
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intx13.2: int $0x13 # BIOS: Disk I/O
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movw %di,%sp # Restore
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popw %si # Restore
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retw # To caller
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# Menu strings
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item: .ascii " "; .byte ' '|0x80
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prompt: .ascii "\nDefault:"; .byte ' '|0x80
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crlf: .ascii "\r"; .byte '\n'|0x80
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# Partition type tables
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tables:
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#
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# These entries identify invalid or NON BOOT types and partitions.
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#
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.byte 0x0, 0x5, 0xf
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#
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# These valuse indicate botable types we know the names of
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#
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.byte 0x1, 0x4, 0x6, 0xb, 0xc, 0xe, 0x63, 0x83
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.byte 0xa5, 0xa6, 0xa9
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#
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# These are offsets that match the known names above and point to the strings
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# that will be printed.
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#
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.byte os_misc-. # Unknown
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.byte os_dos-. # DOS
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.byte os_dos-. # DOS
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.byte os_dos-. # DOS
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.byte os_dos-. # Windows
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.byte os_dos-. # Windows
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.byte os_dos-. # Windows
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.byte os_unix-. # UNIX
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.byte os_linux-. # Linux
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.byte os_freebsd-. # FreeBSD
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.byte os_bsd-. # OpenBSD
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.byte os_bsd-. # NetBSD
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#
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# And here are the strings themselves. 0x80 or'd into a byte indicates
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# the end of the string. (not so great for Russians but...)
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#
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os_misc: .ascii "?"; .byte '?'|0x80
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os_dos: .ascii "DO"; .byte 'S'|0x80
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os_unix: .ascii "UNI"; .byte 'X'|0x80
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os_linux: .ascii "Linu"; .byte 'x'|0x80
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os_freebsd: .ascii "Free"
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os_bsd: .ascii "BS"; .byte 'D'|0x80
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.org PRT_OFF-0xc,0x90
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.org PRT_OFF-0xe,0x90
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#
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# These values are sometimes changed before writing back to the drive
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# Be especially careful that nxtdrv: must come after drive:, as it
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# is part of the same string.
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#
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# Note that the 'drive' string variable is used as the second signature
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# check in boot0cfg(8).
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#
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version_minor: .byte 0x1 # minor version
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version_major: .byte 0x1 # major version
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drive: .ascii "Drive "
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nxtdrv: .byte 0x0 # Next drive number
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opt: .byte 0x0 # Option
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@ -410,3 +426,125 @@ ticks: .word TICKS # Delay
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#
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partbl: .fill 0x40,0x1,0x0 # Partition table
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.word MAGIC # Magic number
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#
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# start of sector two.. ugh
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#
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.org SECTOR_SIZE,0x90
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# Menu strings
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item: .ascii " "; .byte ' '|0x80
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prompt: .ascii "\nDefault:"; .byte ' '|0x80
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crlf: .ascii "\r"; .byte '\n'|0x80
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# Partition type tables
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tables:
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#
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# These entries identify invalid or NON BOOT types and partitions.
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#
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table0: .byte 0x0, 0x5, 0xf
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table0_end:
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#
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# These valuse indicate botable types we know the names of
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#
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table1: .byte 0x1, 0x4, 0x6, 0x7, 0xb, 0xc, 0xe, 0x63, 0x83
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.byte 0xa5, 0xa6, 0xa9, 0xb7
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table1_end:
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#
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# These are offsets that match the known names above and point to the strings
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# that will be printed.
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#
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.byte os_misc-. # Unknown
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.byte os_dos-. # DOS
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.byte os_dos-. # DOS
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.byte os_dos-. # DOS
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.byte os_nt-. # NT or OS/2
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.byte os_windows-. # Windows
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.byte os_windows-. # Windows
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.byte os_windows-. # Windows
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.byte os_unix-. # UNIX
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.byte os_linux-. # Linux
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.byte os_freebsd-. # FreeBSD
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.byte os_openbsd-. # OpenBSD
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.byte os_netbsd-. # NetBSD
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.byte os_bsdos-. # BSD/OS
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#
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# And here are the strings themselves. 0x80 or'd into a byte indicates
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# the end of the string. (not so great for Russians but...)
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#
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os_misc: .ascii "Unknow"; .byte 'n'|0x80
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os_dos: .ascii "DO"; .byte 'S'|0x80
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os_nt: .ascii "Windows N"; .byte 'T'|0x80
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os_windows: .ascii "Window"; .byte 's'|0x80
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os_unix: .ascii "UNI"; .byte 'X'|0x80
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os_linux: .ascii "Linu"; .byte 'x'|0x80
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os_freebsd: .ascii "FreeBS"; .byte 'D'|0x80
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os_openbsd: .ascii "OpenBS"; .byte 'D'|0x80
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os_netbsd: .ascii "NetBS"; .byte 'D'|0x80
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os_bsdos: .ascii "BSD/O"; .byte 'S'|0x80
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#
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# A set of functions to print out various parts of %ax in hex
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#
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hex16: callw hex16.1 # Do upper 8
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hex16.1: xchgb %ah,%al # Save/restore
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hex8: push %ax # Save
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shrb $0x4,%al # Do upper
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callw hex8.1 # 4
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pop %ax # Restore
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hex8.1: andb $0xf,%al # Get lower 4
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cmpb $0xa,%al # Convert
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sbbb $0x69,%al # to hex
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das # digit
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orb $0x20,%al # To lower case
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push %ax # Save
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callw putchr # Print char
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pop %ax # Restore
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retw # (Recursive)
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#
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# Function to display a hexdump of memory. Call with:
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#
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# %dx - word - number of lines to display, each line is 16 bytes
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# %ds:(%si) - caddr_t - memory to display
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#
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memdump: movw %si,%ax # Display the
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callw hex16 # memory offset
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movb $':',%al # Output a seperator
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callw putchr # between the
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movb $' ',%al # offset and
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callw putchr # the data
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push %si # Save %si
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movw $16,%cx # Bytes per line
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memdump.1: lodsb # Get next byte
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callw hex8 # and display it
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movb $' ',%al # Determine which
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cmpb $9,%cl # seperator
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jne memdump.2 # to use
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movb $'-',%al # and then
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memdump.2: callw putchr # display it
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loop memdump.1 # Next byte
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movb $'|',%al # Start of character
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callw putchr # display
|
||||
pop %si # Restore %si
|
||||
movb $16,%cl # Bytes per line
|
||||
memdump.3: lodsb # Get next byte
|
||||
cmpb $32,%al # Control character?
|
||||
jb memdump.4 # Yes, so modify
|
||||
cmpb $0x80,%al # Upper ASCII?
|
||||
jb memdump.5 # No, use raw characer
|
||||
memdump.4: movb $'.',%al # Use '.' instead of bad char
|
||||
memdump.5: callw putchr # Output character
|
||||
loop memdump.3 # Do whole line
|
||||
movb $'|',%al # Start of character
|
||||
callw putchr # display
|
||||
push %si # Save %si
|
||||
callw putn # New line
|
||||
pop %si # Restore %si
|
||||
dec %dx # Done yet?
|
||||
jnz memdump # No, keep going
|
||||
retw # Yes, return
|
||||
|
||||
.org SECTOR_SIZE*NUM_SECTORS, 0x0
|
||||
fake:
|
||||
|
||||
Loading…
Reference in New Issue
Block a user