Add support for sending messages to the serial console which is helpful
when debugging boot problems. It is not on by default but is enabled via the BTX_SERIAL variable. The port and speed can be set via the same variables used by boot2 and the loader.
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@ -14,6 +14,15 @@ BOOT_BTX_FLAGS=0x0
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AFLAGS+= --defsym BTX_FLAGS=${BOOT_BTX_FLAGS}
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.if defined(BTX_SERIAL)
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BOOT_COMCONSOLE_PORT?= 0x3f8
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BOOT_COMCONSOLE_SPEED?= 9600
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B2SIOFMT?= 0x3
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M4FLAGS+= -DBTX_SERIAL -DSIOPRT=${BOOT_COMCONSOLE_PORT} \
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-DSIOFMT=${B2SIOFMT} -DSIOSPD=${BOOT_COMCONSOLE_SPEED}
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.endif
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ORG= 0x9000
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all: btx
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@ -240,6 +240,9 @@ init.8: xorl %ecx,%ecx # Zero
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movb $0x7,%cl # Set remaining
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init.9: push $0x0 # general
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loop init.9 # registers
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ifdef(`BTX_SERIAL',`
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call sio_init # setup the serial console
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')
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popa # and initialize
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popl %es # Initialize
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popl %ds # user
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@ -967,6 +970,80 @@ putstr: lodsb # Load char
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testb %al,%al # End of string?
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jnz putstr.0 # No
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ret # To caller
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ifdef(`BTX_SERIAL',`
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.set SIO_PRT,SIOPRT # Base port
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.set SIO_FMT,SIOFMT # 8N1
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.set SIO_DIV,(115200/SIOSPD) # 115200 / SPD
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# void sio_init(void)
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sio_init: movw $SIO_PRT+0x3,%dx # Data format reg
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movb $SIO_FMT|0x80,%al # Set format
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outb %al,(%dx) # and DLAB
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pushl %edx # Save
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subb $0x3,%dl # Divisor latch reg
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movw $SIO_DIV,%ax # Set
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outw %ax,(%dx) # BPS
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popl %edx # Restore
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movb $SIO_FMT,%al # Clear
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outb %al,(%dx) # DLAB
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incl %edx # Modem control reg
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movb $0x3,%al # Set RTS,
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outb %al,(%dx) # DTR
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incl %edx # Line status reg
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# void sio_flush(void)
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sio_flush.0: call sio_getc.1 # Get character
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sio_flush: call sio_ischar # Check for character
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jnz sio_flush.0 # Till none
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ret # To caller
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# void sio_putc(int c)
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sio_putc: movw $SIO_PRT+0x5,%dx # Line status reg
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xor %ecx,%ecx # Timeout
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movb $0x40,%ch # counter
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sio_putc.1: inb (%dx),%al # Transmitter
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testb $0x20,%al # buffer empty?
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loopz sio_putc.1 # No
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jz sio_putc.2 # If timeout
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movb 0x4(%esp,1),%al # Get character
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subb $0x5,%dl # Transmitter hold reg
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outb %al,(%dx) # Write character
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sio_putc.2: ret $0x4 # To caller
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# int sio_getc(void)
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sio_getc: call sio_ischar # Character available?
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jz sio_getc # No
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sio_getc.1: subb $0x5,%dl # Receiver buffer reg
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inb (%dx),%al # Read character
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ret # To caller
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# int sio_ischar(void)
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sio_ischar: movw $SIO_PRT+0x5,%dx # Line status register
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xorl %eax,%eax # Zero
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inb (%dx),%al # Received data
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andb $0x1,%al # ready?
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ret # To caller
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#
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# Output character AL to the serial console.
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#
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putchr: pusha # Save
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cmpb $10, %al # is it a newline?
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jne putchr.1 # no?, then leave
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push $13 # output a carriage
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call sio_putc # return first
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movb $10, %al # restore %al
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putchr.1: pushl %eax # Push the character
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# onto the stack
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call sio_putc # Output the character
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popa # Restore
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ret # To caller
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',`
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#
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# Output character AL to the console.
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#
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@ -240,6 +240,9 @@ init.8: xorl %ecx,%ecx # Zero
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movb $0x7,%cl # Set remaining
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init.9: push $0x0 # general
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loop init.9 # registers
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ifdef(`BTX_SERIAL',`
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call sio_init # setup the serial console
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')
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popa # and initialize
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popl %es # Initialize
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popl %ds # user
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@ -967,6 +970,80 @@ putstr: lodsb # Load char
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testb %al,%al # End of string?
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jnz putstr.0 # No
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ret # To caller
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ifdef(`BTX_SERIAL',`
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.set SIO_PRT,SIOPRT # Base port
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.set SIO_FMT,SIOFMT # 8N1
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.set SIO_DIV,(115200/SIOSPD) # 115200 / SPD
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# void sio_init(void)
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sio_init: movw $SIO_PRT+0x3,%dx # Data format reg
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movb $SIO_FMT|0x80,%al # Set format
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outb %al,(%dx) # and DLAB
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pushl %edx # Save
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subb $0x3,%dl # Divisor latch reg
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movw $SIO_DIV,%ax # Set
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outw %ax,(%dx) # BPS
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popl %edx # Restore
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movb $SIO_FMT,%al # Clear
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outb %al,(%dx) # DLAB
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incl %edx # Modem control reg
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movb $0x3,%al # Set RTS,
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outb %al,(%dx) # DTR
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incl %edx # Line status reg
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# void sio_flush(void)
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sio_flush.0: call sio_getc.1 # Get character
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sio_flush: call sio_ischar # Check for character
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jnz sio_flush.0 # Till none
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ret # To caller
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# void sio_putc(int c)
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sio_putc: movw $SIO_PRT+0x5,%dx # Line status reg
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xor %ecx,%ecx # Timeout
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movb $0x40,%ch # counter
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sio_putc.1: inb (%dx),%al # Transmitter
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testb $0x20,%al # buffer empty?
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loopz sio_putc.1 # No
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jz sio_putc.2 # If timeout
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movb 0x4(%esp,1),%al # Get character
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subb $0x5,%dl # Transmitter hold reg
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outb %al,(%dx) # Write character
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sio_putc.2: ret $0x4 # To caller
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# int sio_getc(void)
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sio_getc: call sio_ischar # Character available?
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jz sio_getc # No
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sio_getc.1: subb $0x5,%dl # Receiver buffer reg
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inb (%dx),%al # Read character
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ret # To caller
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# int sio_ischar(void)
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sio_ischar: movw $SIO_PRT+0x5,%dx # Line status register
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xorl %eax,%eax # Zero
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inb (%dx),%al # Received data
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andb $0x1,%al # ready?
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ret # To caller
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#
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# Output character AL to the serial console.
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#
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putchr: pusha # Save
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cmpb $10, %al # is it a newline?
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jne putchr.1 # no?, then leave
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push $13 # output a carriage
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call sio_putc # return first
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movb $10, %al # restore %al
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putchr.1: pushl %eax # Push the character
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# onto the stack
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call sio_putc # Output the character
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popa # Restore
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ret # To caller
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',`
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#
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# Output character AL to the console.
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#
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