how to debug mips or arm platform applications by cgdb

[loody]

Dear all:
Would someone tell me how to debug mips or arm applications by CGDB.
I have cross-toolchain like arm-linux-gdb, but I have no idea how to
embed it with cgdb.
Should I recompile cgdb with arm-linux target or only replace the
build-in gdb with arm-linux-gdb?
thanks for your help,
miloody

[Duane Ellis]

Post by loody
Would someone tell me how to debug mips or arm applications by CGDB.

By CGDB, I presume you mean "cross gdb".

You need to describe your target better.

===========
(A) Is your target running linux?
===========

If so, if your development host is not your target, (ie: cross work),
you need a "gdb-server" application for your target. That "gdb server"
would talk via RS232 (serial) or TCP/IP (ethernet) back to your
development host.

You can "simulate" the TCP environment quite easily using "local host"
on your development host so you can more easily understand how this
works. It can be confusing the first few times you do it.

You can learn how to run "gdb server" on your development host, (aka:
"local host"), and connect to the server using the GDB command: "target
remote localhost:port" ... 90% of the battle is understanding how
"gdbserver and target remote works" - doing that with "localhost" and a
"development host program" is sometimes a little easier to understand
and figure out.

Only then - change "target remote localhost" to "target remote
<ip-address-of-your-target-linux-board>".

===========
(B) is your target running standalone - no operating system, or
something other then linux.
===========

For example, you might be debugging "UBOOT" or some other FLASH MEMORY
type device, perhaps like: 'contiki' or 'freertos' or 'ethernut'

Some use JTAG to debug the Linux Kernel.

In this case, 2 options:

(a) A serial rom monitor that talks the GDB protocol (very rare these
days, most people use jtag).

(b) A JTAG dongle, and software for that jtag dongle that understands
the GDB protocol.

You'll need to *PURCHASE* a jtag dongle (or make one) - I highly
recommend a "USB based ftdi-2232 based dongle", and *STRONGLY* do not
recommend a "printer-port" solution.

The "jtag dongle method" - is 80% identical to the GDBREMOTE example
above - but is more complicated (20%) because you have to create an
initialization script to setup your target board, program the cpu
clocks, erase & program the flash memory, stuff like that.

A *VERY* common JTAG solution (de-facto for ARM) is: "openocd" - see:
http://openocd.berlios.de/web

In the JTAG dongle case, GDB talks "target remote" to a GDB server
program running on Linux, or Windows, or in some cases the DONGLE is
really a tiny computer that talks the GDBSERVER protocol over Ethernet
(the Zylin zy1000 is an example, it actually runs OpenOCD inside).

-Duane.

[loody]

Post by Duane Ellis

Post by loody
Would someone tell me how to debug mips or arm applications by CGDB.

By CGDB, I presume you mean "cross gdb".
You need to describe your target better.
===========
(A)  Is your target running linux?
===========
If so, if your development host is not your target, (ie: cross work), you
need a "gdb-server" application for your target. That "gdb server" would
talk via RS232 (serial) or TCP/IP (ethernet) back to your development host.
You can "simulate" the TCP environment quite easily using "local host" on
your development host so you can more easily understand how this works. It
can be confusing the first few times you do it.
You can learn how to run "gdb server" on your development host, (aka: "local
host"), and connect to the server using the GDB command: "target remote
localhost:port" ...   90% of the battle is understanding how "gdbserver and
target remote works" - doing that with "localhost" and a "development host
program" is sometimes a little easier to understand and figure out.
Only then - change "target remote localhost" to   "target remote
<ip-address-of-your-target-linux-board>".

First all, I have to appreciate your kind and detail help and sorry
for late replying this letter.

My cgdb is an application which combine curses (terminal-based)
interface to the GNU Debugger (GDB).
It is a more light weight process than ddd.
But your explanation is the answer of next question I want to ask :)
I intend to use cgdb instead of sde-insight to debug the program
running on the target board.
But I don't realize the whole story at all until reading your letter.

Post by Duane Ellis
===========
(B) is your target running standalone - no operating system, or something
other then linux.
===========
For example, you might be debugging "UBOOT" or some other FLASH MEMORY type
device, perhaps like: 'contiki' or 'freertos' or 'ethernut'
Some use JTAG to debug the Linux Kernel.
(a) A serial rom monitor that talks the GDB protocol (very rare these days,
most people use jtag).
(b) A JTAG dongle, and software for that jtag dongle that understands the
GDB protocol.
You'll need to *PURCHASE* a jtag dongle (or make one) - I highly recommend a
"USB based ftdi-2232 based dongle", and *STRONGLY* do not recommend a
"printer-port" solution.
The "jtag dongle method" - is 80% identical to the GDBREMOTE example above -
but is more complicated (20%) because you have to create an initialization
script to setup your target board, program the cpu clocks, erase & program
the flash memory, stuff like that.
 http://openocd.berlios.de/web
In the JTAG dongle case, GDB talks "target remote" to a
GDB server program running on Linux, or Windows, or in some cases the DONGLE is really a tiny
computer that talks the GDBSERVER protocol over Ethernet (the Zylin zy1000
is an example, it actually runs OpenOCD inside).

from the case you mention above, there seems a gdbserver running on
the dongle not on the target board such that
when we send gdb protocol from host to the dongle, it can translate it
to the proper jtag instructions to handle the target board.

Is my assumption correct?
Thanks for your help,
miloody

[Duane Ellis]

loody> Would someone tell me how to debug mips or arm applications by CGDB.

duane> You need to describe your target better.

[... snip ...]

[answer: Basically a standalone board, NO OS]

duane> ....

Post by loody

Post by Duane Ellis
(a) A serial rom monitor that talks the GDB protocol (very rare these days,
most people use jtag).
(b) A JTAG dongle, and software for that jtag dongle that understands the
GDB protocol.
You'll need to *PURCHASE* a jtag dongle (or make one) - I highly recommend a
"USB based ftdi-2232 based dongle", and *STRONGLY* do not recommend a
"printer-port" solution.
The "jtag dongle method" - is 80% identical to the GDBREMOTE example above -
but is more complicated (20%) because you have to create an initialization
script to setup your target board, program the cpu clocks, erase & program
the flash memory, stuff like that.
http://openocd.berlios.de/web
In the JTAG dongle case, GDB talks "target remote" to a
GDB server program running on Linux, or Windows, or in some cases the DONGLE is really a tiny
computer that talks the GDBSERVER protocol over Ethernet (the Zylin zy1000
is an example, it actually runs OpenOCD inside).

loody> ...

Post by loody
from the case you mention above, there seems a gdbserver running on
the dongle not on the target board such that
when we send gdb protocol from host to the dongle, it can translate it
to the proper jtag instructions to handle the target board.
Is my assumption correct?
Thanks for your help,

Yes, exactly. Some are standalone and self contained "dongles" - ie:
ZYLIN Z1000 (it has an Ethernet connector). Others are a cheap piece of
hardware (few chips) and the software runs on your PC under windoze, or
Linux (ie: OpenOCD is an example of that).

If the GDB server runs on the target (with no operating system present)
- it is most typically a ROM monitor of some sort. The problem with this
sort of platform is this: If your program goes off into the weeds - so
might your ROM monitors ability to respond to GDB requests. Example:
You are using a serial port to respond to GDB requests. If your program
*disables* interrupts and gets hung up, there will be no more serial
port interrupts. GDB will be ignored.

Another variant of this is a commercial product. In the past I used the
"ARM" version of the "EPI TOOLS" majic debugger. Which, is/was a
fantastic package with fantastic support. Today, they are owned by
Mentor. I have no experience since Mentor's acquisition, nor their MIPS
variant of their debuggers. My experience with Mentor though has always
been very positive.

http://www.mentor.com/products/embedded_software/majic-jtag-probe/

Another variant is offered by "Green Hills Software".
And another is Lauterbach software.
(They also often include/require use of their compiler and/or tools).

-Duane.









Be