I want to debug program remotely. But the issue is my program is using signals.
On local machine I handle signal using following command:
handle SIG64 nostop noprint
But for remotely debugging using gdbserver , I don't know how to handle signals.
Here is what I am doing:
remote$ gdbserver :2345 hello_world
Process hello_world created; pid = 2509
Listening on port 2345
local$ gdb -q hello_world
Reading symbols from /home/user/hello_world...done.
(gdb) target remote 192.168.0.11:2345
Remote debugging using 192.168.0.11:2345
0x002f3850 in ?? () from /lib/ld-linux.so.2
(gdb) continue
Any help would be highly appreciated.
Thanks & BR,
Yuvi
The handle SIG64 nostop noprint command should work remotely just as well.
Related
I am trying to use gdbserver...
I have an application with binary path /user/bin/foo running with pid 19767.
Started the gdbserver on remote:
gdbserver --remote-debug --multi 0:12347
Started gdb on client and connected it to remove server
target extended-remote 192.168.1.84:12347
Attached gdb on pid
attach 19767
It shows:
warning: Could not load vsyscall page because no executable was specified
try using the "file" command first.
0x00007f207550043c in ?? ()
Also, current thread information it is showing is incorrect. Like info threads shows 1 thread , but my app has 10 threads-
(gdb) info threads
* 1 Thread 19767.19767 0x00007f207550043c in ?? ()
How can I ask gdb to load symbol from remote file /user/bin/foo? How to make it show correct info?
How can I ask gdb to load symbol from remote file /user/bin/foo
You can't. Copy remote /usr/bin/foo locally (or mount the filesystem it's on), and then invoke gdb like this: gdb /path/to/copy/of/foo, or just use the file command.
As of gdb 7.10, you can use
set sysroot target:
to make gdb retrieve files from the remote filesystem. See https://sourceware.org/gdb/onlinedocs/gdb/Files.html#Files
We're running squid from with gdb - that way we can automatically generate backtraces for debugging.
backtrace=`mktemp`
gdb -q -x /etc/service/squid3/gdbcommands /usr/sbin/squid 2>&1 >$backtrace
/usr/bin/mail -s "`hostname`: Squid was restarted (backtrace)" someaddress#charite.de < backtracetrace
rm $backtrace
/etc/service/squid3/gdbcommands contains:
set args -NsYC
handle SIGPIPE pass nostop noprint
handle SIGTERM pass nostop noprint
handle SIGUSR1 pass nostop noprint
handle SIGHUP pass nostop noprint
handle SIGSEGV stop
handle SIGABRT stop
run
set print pretty
backtrace full
generate-core-file
quit
But, every now and then, squid is "just" being stopped & restarted, with no crash being involved at all. In that case I'm still getting an email containing:
Reading symbols from /usr/sbin/squid...done.
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[Inferior 1 (process 57867) exited normally]
/etc/service/squid3/gdbcommands:10: Error in sourced command file:
No stack.
(gdb) quit
And of course there's no stack, since the program exited ok.
How can I change my gdbcommands file to avoid this?
This can be done using either Python or the gdb CLI. Since the CLI is a bit simpler, when possible, I'll sketch that approach.
First, you might as well only create a core file on a bad exit. And, we'll use the gdb exit code later, so let's arrange for that to tell the calling script what happened.
Where your current script says:
backtrace full
generate-core-file
quit
... instead use:
if !$_isvoid($_exitsignal) || (!$_isvoid($_exitcode) && $_exitcode != 0))
backtrace full
generate-core-file
quit 0
end
quit 1
Then your calling script can check the exit code of gdb:
if gdb your args here; then
mail results
fi
If I start a normal 'gdb' session, then I can reach STDIN and see STDOUT directly in the terminal:
$ gdb wc
GNU gdb (Gentoo 7.10.1 vanilla) 7.10.1
...
gdb> run
Starting program: /usr/bin/wc
asdf
1 1 5
[Inferior 1 (process 28131) exited normally]
gdb> quit
$
Can I do the same with a gdbserver???
Here is what I have tried (gdbserver):
$ gdbserver /dev/ttyS0 wc
Process wc created; pid = 28156
Listening on port 2345
and client:
$ gdb
GNU gdb (Gentoo 7.10.1 vanilla) 7.10.1
...
gdb> c
Continuing.
Program received signal SIGINT, Interrupt.
0x00007ffff7ddbc40 in _start () from target:/lib64/ld-linux-x86-64.so.2
gdb>
But, it seems like STDIN/STDOUT is not being connected when using the gdbserver.
How can I run remote debugging over the serial line, and also access STDIN/STDOUT of the application that I'm debugging over the same serial line??
How can I run remote debugging over the serial line, and also access STDIN/STDOUT of the application that I'm debugging over the same serial line??
You'll need to use screen or tmux to multiplex gdb<->gdbserver and keyboard->application traffic over a single serial line.
I am remote debugging a Stellaris Launchpad. I use OpenOCD to connect to the stellaris and then connect GDB to the server provided by openOCD. I use Open On-Chip Debugger 0.10.0-dev-00002-g79fdeb3 (2015-07-09-23:28). GDB is the one from arm-gcc-none-eabi, the 4_9-2015q1 release.
I invoke openOCD like this:
/usr/local/bin/openocd --file \
/usr/local/share/openocd/scripts/board/ek-lm4f120xl.cfg \
>> openocdLog.txt 2>&1 &
And then GDB like this:
arm-none-eabi-gdb proj//debug/exec -x gdb//gdb.script
gdb/gdb.script contains:
set remotetimeout 10000
target extended-remote :3333
monitor reset halt
load
monitor reset init
The problem is that whenever I hit control+c GDB disconnects. Normally this would halt the remote, but GDB just disconnects:
(gdb) cont
Continuing.
^CError detected on fd 6
Remote communication error. Target disconnected.: Interrupted system call.
(gdb)
OpenOCD has the following things to say, this one while GDB is launching:
Warn : keep_alive() was not invoked in the 1000ms timelimit. GDB alive packet not sent! (1258). Workaround: increase "set remotetimeout" in GDB
Which is weird, considering the gdb/gdb.script file forces remotetimeout to an insanly large number.
And when pressing control+c openOCD says:
Debug: 2602 5089 hla_interface.c:119 hl_interface_quit(): hl_interface_quit
So, how do I resolve this? How can I make GDB halt the remote instead of disconnecting when pressing control+c?
The problem was OpenOCD being too bleeding edge. I had issues with 0.6.1, but version 0.7.0 of OpenOCD works great.
I'm trying to debug a program on my board which runs an embedded linux and I have Ubuntu as host system. I have a big problem with gdbserver. You see the thing is that my board doesn't have an Ethernet interface but a serial device which I'm using for console and I noticed that you can use a serial device for debugging in gdbserver although I couldn't find an example of this considering everyone that used gdbserver in videos or books used it in TCP mode which I can't do that.
So What I did was simply running gdbserver on the board this way:
root#DM368# gdbserver /dev/ttyS0 hello
Process hello created; pid = 472
On the host side I'm using ddd program and I ran:
root#mosi-VirtualBox:~# ddd --debugger arm-linux-gdb
And in ddd window terminal I entered:
(gdb) cd /root/home/mySimpleHello/hello
(gdb) target remote /dev/ttyUSB0
(gdb) file hello
And /dev/ttyUSB0 is connected to the board's /dev/ttyS0
But I don't get anything back in gdb and there is nothing in gdbserver output which is kind of weird. I mean not a single message like a "host connected" or "remote debugging from ..." or things like that. And in ddd when I ran:
(gdb) b main
Breakpoint 1 at 0x83ac: file hello.c, line 10.
(gdb) run
Then gdb says:
the program in not being run
I tried with gdb on Ubuntu's terminal directly (whitout ddd) and the same thing happened. I even tried with eclipse and I setup a debugging profile in eclipse and I installed gdb-multiarch program and used that in eclipse with its .gdbinit file set to arm. Nothing happens and I have no idea why this simple procedure wouldn't work.
Does somebody have any idea? What am I doing wrong? How can I debug a program using a serial connection?