c_load

MIPS处理器的bootloader,龙芯就是用的修改过的PMON2

The load Command
load

The load command downloads programs and data from the host. 

Format

The format for the load command is:

load [-abeistB] [-baud] [offset] [-c cmdstr] filename

where:

-m	Only load the symbol information.

-a	suppresses addition of an offset to symbols.

-b	suppresses deletion of all breakpoints before the download. 

-e	suppresses clearing of the exception handlers.

-i	ignores checksum errors.

-s	suppresses clearing of the symbol table before the download.

-t	loads at the top of memory (PMON only).

-f	load driver from flash (IMON only).

-B	Interprets input from host as binary data for Ethernet 
	transfers.

-baud		sets the baud rate for transfer.

offset		loads at the specified offset.

-c cmdstr	sets a command string that the Monitor sends to the host to 
		start a download operation. String cmdstr is the string that 
		starts the download. Note that the command string must be 
		enclosed in double quotation marks if the string contains any 
		spaces.

filename	load the specified file (imon95 only).

Invoking the load command with no parameters or arguments clears the 
symbol table, deletes all current breakpoints, allows the Monitor to receive 
programs or data from the host, and uses the current baud rate by default.

Functional Description

The load command accepts programs and data from the host port in LSI
Logic's proprietary FastLoad format, Motorola S-record, or binary files.  The user can
set environment variables to change the data port, the format, and the
transfer protocol. 

The load command normally clears the symbol table, exception handlers, 
and all breakpoints. The -s and -b options suppress the clearing of the 
symbol table and breakpoints, respectively. The value of the EPC register 
is set automatically to the entry point of the program. Therefore, to execute 
the downloaded program, only the g command is required.

The -c option permits a command string to be sent to the host when the 
load command is issued. This is intended for use in conjunction with the 
transparent mode. Note that if the command string contains multiple 
words, the command must be enclosed in double quotation marks, as 
shown in the example below.

The load command returns the error message "out of memory" if there is 
insufficient space in the heap for the program's global symbols. To 
increase the size of the heap , use the set heaptop command to reserve 
more space in the heap, and then use the -T option with the pmcc command 
to set the start address of the text section to the same address that was 
specified for the heap. See the pmcc command on page 3-13.

The dlecho, dlproto, and hostport Variables

The dlecho, dlproto, and hostport variables control operation of the 
download. The following table shows how these environment variables affect the 
operation of the load command.

VariableAction
dlecho offDo not echo the lines
dlecho onEcho the lines
dlecho lfeedEcho only a linefeed for each line
dlproto noneDo not use a protocol
dlproto XonXoffSend Xon and Xoff to control the host
dlproto EtxAckExpect Etx as end of record, send Ack
hostport tty0Select tty0 as the port to which the host is connected
hostport tty1Select tty1 as the port to which the host is connected
hostport ethernetSelect ethernet
as the port to which the host is connected

See the section on downloading beginning on page 1-9 for more 
information on these variables and the use of the load command.

Examples

Download to tty1 using the edown program.

	PMON set dlecho off 
	PMON set hostport tty1 
	PMON set dlproto EtxAck 
	PMON load 	
	% edown 

Download to tty0 using a terminal emulator.

	PMON set dlecho off 
	PMON set hostport tty0 
	PMON set dlproto none 
	PMON load 	
	-- use terminal emulator's "send text file" command
	Downloading from tty0, ^C to abort
	Entry address is 80020000

	Total = 0x00043C00 bytes
	PMON

When using the Monitor in an environment where
tty1 is connected to a login line on a Unix host. You will need to send
a command to start the download. In the following example the command
"cat test1.rec" is sent to the host.

	PMON load -c "cat test1.rec"

Files
The code for the load command is located in 
pmon/load.c (PMON), 
and imon/load.c (IMON).

See Also
set command for the setup 
of the environment variables.