gdb.info: MIPS Embedded
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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
Use these GDB commands to specify the connection to your target
`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
host$ gdb PROG
GDB is free software and ...
(gdb) target mips /dev/ttyb
(gdb) load PROG
`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
`target pmon PORT'
PMON ROM monitor.
`target ddb PORT'
NEC's DDB variant of PMON for Vr4300.
`target lsi PORT'
LSI variant of PMON.
`target r3900 DEV'
Densan DVE-R3900 ROM monitor for Toshiba R3900 Mips.
`target array DEV'
Array Tech LSI33K RAID controller board.
GDB also supports these special commands for MIPS targets:
`set processor ARGS'
Use the `set processor' command to set the type of MIPS processor
when you want to access processor-type-specific registers. For
example, `set processor R3041' tells GDB to use the CPU registers
appropriate for the 3041 chip. Use the `show processor' command
to see what MIPS processor GDB is using. Use the `info reg'
command to see what registers GDB is using.
`set mipsfpu double'
`set mipsfpu single'
`set mipsfpu none'
If your target board does not support the MIPS floating point
coprocessor, you should use the command `set mipsfpu none' (if you
need this, you may wish to put the command in your GDB init 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.
If you are using a floating point coprocessor with only single
precision floating point support, as on the R4650 processor, use
the command `set mipsfpu single'. The default double precision
floating point coprocessor may be selected using `set mipsfpu
In previous versions the only choices were double precision or no
floating point, so `set mipsfpu on' will select double precision
and `set mipsfpu off' will select no floating point.
As usual, you can inquire about the `mipsfpu' variable with `show
`set remotedebug N'
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'
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'.)
The timeout set by `set timeout' does not apply when GDB is
waiting for your program to stop. In that case, GDB waits forever
because it has no way of knowing how long the program is going to
run before stopping.
Created Mon Nov 8 17:42:39 2004 on tillpc with info_to_html version 0.9.6.