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GDB and remote MIPS boards

GDB can use the MIPS remote debugging protocol to talk to a MIPS board attached to a serial line. This is available when you configure GDB with `--target=mips-idt-ecoff'.

Use these GDB commands to specify the connection to your target board:

target mips port

To run a program on the board, start up gdb with the name of your program as the argument. To connect to the board, use the command `target mips port', where port is the name of the serial port connected to the board. If the program has not already been downloaded to the board, you may use the load command to download it. You can then use all the usual GDB commands.

For example, this sequence connects to the target board through a serial port, and loads and runs a program called prog through the debugger:

host$ gdb prog
GDB is free software and ...
(gdb) target mips /dev/ttyb
(gdb) load prog
(gdb) run

target mips hostname:portnumber

On some GDB host configurations, you can specify a TCP connection (for instance, to a serial line managed by a terminal concentrator) instead of a serial port, using the syntax `hostname:portnumber'.

GDB also supports these special commands for MIPS targets:

set mipsfpu off

show mipsfpu

If your target board does not support the MIPS floating point coprocessor, you should use the command `set mipsfpu off' (if you need this, you may wish to put the command in your .gdbinit file). This tells GDB how to find the return value of functions which return floating point values. It also allows GDB to avoid saving the floating point registers when calling functions on the board. (As usual, you can inquire about the mipsfpu variable with `show mipsfpu'.)

set remotedebug n

show remotedebug

You can see some debugging information about communications with the board by setting the remotedebug variable. If you set it to 1 using `set remotedebug 1', every packet is displayed. If you set it to 2, every character is displayed. You can check the current value at any time with the command `show remotedebug'.

set timeout seconds

set retransmit-timeout seconds

show timeout

show retransmit-timeout

You can control the timeout used while waiting for a packet, in the MIPS remote protocol, with the set timeout seconds command. The default is 5 seconds. Similarly, you can control the timeout used while waiting for an acknowledgement of a packet with the set retransmit-timeout seconds command. The default is 3 seconds. You can inspect both values with show timeout and show retransmit-timeout. (These commands are only available when GDB is configured for `--target=mips-idt-ecoff'.)

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