Debug Q With GDB Debugger - c++

This is really a general question.
And I've tried looking around for help but it's about the gdp debugger.
I compile a program, it takes two strings as arguments.
I run it with r and the two parameters following it, but when I insert a break like ' break 33 ' and break at line 33 and then run it again, I cannot step into it and it doesn't stop at my break.
I can't step break continue etc.
gcc -g -o debugme debugme.c
Directory: /home/
Tue Oct 6 20:03:14 EDT 2015
[]$ debugme "hi there" "bye bye"
String '0' - 'debugme'
String '1' - 'hi there'
String '2' - 'bye bye'
Total number of command-line arguments: 2
(gdb)
Tue Oct 6 20:06:56 EDT 2015
[]$ cd cosc220
[]$ gdb debugme
GNU gdb (GDB; openSUSE 13.1) 7.6.50.20130731-cvs
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-suse-linux".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://bugs.opensuse.org/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word".
..
Reading symbols from /home/...done.
(gdb) break 33
Breakpoint 1 at 0x4005c7: file debugme.c, line 33.
(gdb) delete 1
(gdb)
(gdb) break 33
Breakpoint 2 at 0x4005c7: file debugme.c, line 33.
(gdb)
What do I need to type for this to work?
It tells me my program isn't running, I try viewing my call stack and it's empty
I type r for run later (I just didn't include it here)

You need to hit r at the gdb so that your program again start running.

What do I need to type for this to work?
You should probably read an introduction, such as this one.
The command you are looking for is run, but once you run your program to the breakpoint, it's likely that you'll have more questions, so starting at introduction may still be a good idea.

It turns out that we didn't have it installed on the server at my school...
Face-palm, it's working now.

Related

My gdb debugger isn't responding when I launch it

I tried to setup the gdb debugger today which was already a hassle in itself. Now that it works (I can launch it at least) it gets stuck none of my commands have any effect on the debugger. I launch the debugger like so:
$ g++ main.cpp -g
$ gdb ./a.out
I can run layout next when I type run it just doesn't respond anymore.
I put an infinite loop in my program on purpose to see simulate a bug. Even without the loop its the exact same behavior.
It also doesn't say "done" when reading in the compiled file:
Now when I try to start gdb without any files specified. This is what happens:
➜ gdb
GNU gdb (GDB) 10.1
Copyright (C) 2020 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "x86_64-apple-darwin20.1.0".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<https://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word".
(gdb) file ./a.out
Reading symbols from ./a.out...
Reading symbols from /Users/Documents/coding/C++/testing_c++/testing_c++/a.out.dSYM/Contents/Resources/DWARF/a.out...
../../gdb/thread.c:95: internal-error: struct thread_info *inferior_thread(): Assertion `current_thread_ != nullptr' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? (y or n) y
This is a bug, please report it. For instructions, see:
<https://www.gnu.org/software/gdb/bugs/>.
../../gdb/thread.c:95: internal-error: struct thread_info *inferior_thread(): Assertion `current_thread_ != nullptr' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Create a core file of GDB? (y or n) n

schedBreak(<tick>) gdb debugging function not working

I am trying to create breakpoints and debug gem5 using gdb. I referred to http://www.gem5.org/Debugger_Based_Debugging.
As in the official documentation in the above link, I tried `call schedBreak() but it doesn't work. the following are the full commands:
➜ test-gem5-x86 git:(master) ✗ gdb --args ./build/X86/gem5.opt configs/learning_gem5/part1/simple.py
GNU gdb (Ubuntu 8.1-0ubuntu3) 8.1.0.20180409-git
Copyright (C) 2018 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from ./build/X86/gem5.opt...done.
(gdb) b main
Breakpoint 1 at 0x4b0d20: main. (4 locations)
(gdb) run
Starting program: /home/hari/test-gem5-x86/build/X86/gem5.opt configs/learning_gem5/part1/simple.py
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Breakpoint 1, main (argc=2, argv=0x7fffffffdef8) at build/X86/sim/main.cc:42
42 {
(gdb) call schedBreak(10000)
warn: need to stop all queues
(gdb) c
Continuing.
gem5 Simulator System. http://gem5.org
gem5 is copyrighted software; use the --copyright option for details.
gem5 compiled Aug 26 2019 20:59:02
gem5 started Sep 8 2019 15:17:55
gem5 executing on nirmal-cadsl2, pid 30158
command line: /home/hari/test-gem5-x86/build/X86/gem5.opt configs/learning_gem5/part1/simple.py
Global frequency set at 1000000000000 ticks per second
warn: DRAM device capacity (8192 Mbytes) does not match the address range assigned (512 Mbytes)
0: system.remote_gdb: listening for remote gdb on port 7001
Beginning simulation!
info: Entering event queue # 0. Starting simulation...
Hello world!
Exiting # tick 501393000 because exiting with last active thread context
[Inferior 1 (process 30158) exited normally]
(gdb)
While this other tutorial http://gem5.org/wiki/images/0/0e/ASPLOS2017_gem5_tutorial.pdf (assuming the debug function is not particular to ISA) tells me that the function is actually schedBreakCycle(), it gives me this No symbol "schedBreakCycle" in current context. The full commands shown below.
➜ test-gem5-x86 git:(master) ✗ gdb --args ./build/X86/gem5.opt configs/learning_gem5/part1/simple.py
GNU gdb (Ubuntu 8.1-0ubuntu3) 8.1.0.20180409-git
Copyright (C) 2018 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from ./build/X86/gem5.opt...done.
(gdb) b main
Breakpoint 1 at 0x4b0d20: main. (4 locations)
(gdb) run
Starting program: /home/hari/test-gem5-x86/build/X86/gem5.opt configs/learning_gem5/part1/simple.py
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Breakpoint 1, main (argc=2, argv=0x7fffffffdef8) at build/X86/sim/main.cc:42
42 {
(gdb) call schedBreakCycle(10000)
No symbol "schedBreakCycle" in current context.
(gdb)
gem5 version: ea8c435b6c6c092d72047eee50f125f5ae7347c3
gdb version: GNU gdb (Ubuntu 8.1-0ubuntu3) 8.1.0.20180409-git
Also, if I want to debug ALPHA or ARM full system on my ubuntu 18.04(x86), do I have to use any cross-compiled gdb versions or would native gdb suffice?
The tutorial is correct, you have to pass --debug-break to gem5:
gdb --args gem5.debug --debug-break=1000 ...
and then without breaking at main:
run
call schedBreak(5000)
continue
--debug-break generates a break at time 1000 and makes GDB stop there after main, and from that point, schedBreak does work.
Or alternatively first go to:
tbreak doSimLoop
run
call schedBreak(5000)
continue
schedBreak schedules an event in the event queue, which cannot be ready at main.
The breaks work by raising a signal, which GDB stops at by default.
ALPHA and ARM won't make a difference since schedBreak is a tiny helper to debug the host emulator itself, which is likely an x86 program. To debug the guest code, which is what most people want, see e.g. this tutorial.
Tested gem5 master at e87a293d1ffa6da38ba8fa145e7dc5128138ab77 in an X86 debug build.

gdb of simple hello world program not working as expected on Mac 10.13.6

I was just intending to explore the features of gdb by following:
https://www.youtube.com/watch?v=PorfLSr3DDI&t=212s
While trying to replicate the steps as in the movie above, I got slightly different output:
When I ran
gdb a.out
, I got this:
GNU gdb (GDB) 8.2.1
Copyright (C) 2018 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> 5 user staff 160 May 8 22:46 .
This is free software: you are free to change and redistribute it.wxr-xr-x 1 user staff 8432 May 8 22:46 a.out
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.world.c
This GDB was configured as "x86_64-apple-darwin17.7.0".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
Users-MBP:codecompre_tooltest user$
For help, type "help".ooltest user$
Type "apropos word" to search for commands related to "word"...
Reading symbols from a.out...
warning: dsym file UUID doesn't match the one in /Users/user/Documents/codecompre_tooltest/a.out
(no debugging symbols found)...done.
(gdb) start
Temporary breakpoint 1 at 0x100000f04
Starting program: /Users/user/Documents/codecompre_tooltest/a.out
[New Thread 0x1703 of process 1645]
[New Thread 0x1903 of process 1645]
[New Thread 0x1a03 of process 1645]
[3]+ Stopped gdb a.out
Why is this so, and how can I solve this?
NOTE: I have followed all the steps in:
http://panks.me/posts/2013/11/install-gdb-on-os-x-mavericks-from-source/
https://gist.github.com/kpy3/27014703672ad6d54c00dfc06e45f1ae

GDB in Cygwin is missing sigfe.s?

After doing some programming assignments for school, I decided to start working on some side projects I had in mind. I decided to install vim on Windows and link it properly using Cygwin. I installed gcc and gdb at first, to try to see if everything worked. I made a quick C file that had a few printf's so I could step into them using gdb.
I can set a breakpoint in main, run the program, get the first printf, but the moment I try to step into the next line, an error appears.
(gdb) step
_sigfe_puts () at sigfe.s:7019
7019 sigfe.s: No such file or directory.
I thought I didn't install gdb properly, so I reinstalled to no luck. I tried using UltraGDB to see if it would help, but the same thing happened, this time giving me a much clearer error.
Can't find a source file at "C:/cygwin64/cygwin/src/cygwin/cygwin-2.8.0/cygwin-2.8.0-1.x86_64/build/x86_64-pc-cygwin/winsup/cygwin/sigfe.s"
Locate the file or edit the source lookup path to include its location.
I had a suspicion it had to do with permissions, so I tried to look up said directory and turns out it really does not exist. C:/cygwin64/ does not have a cygwin folder, much less a subfolder called src and so on. What I did find is that there is a folder called x86_64-pc-cygwin in the cygwin64/usr but it does not have a winsup folder at all.
I'm lost as to what I can do now to fix this error, it's been annoying me for the past few days and have not found any fixes regarding this. I assume GDB is looking for this file in the wrong place, but if I have gdb installed using the Cygwin setup executable then shouldn't this be working anyway? Any help would be appreciated, thank you.
Complete test run w/error:
$ gdb ./test
GNU gdb (GDB) (Cygwin 7.10.1-1) 7.10.1
Copyright (C) 2015 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-pc-cygwin".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from ./test...done.
(gdb) break main
Breakpoint 1 at 0x1004010ed: file test.c, line 6.
(gdb) run
Starting program: /home/User/test
[New Thread 13236.0x4c0]
[New Thread 13236.0x824]
[New Thread 13236.0x3078]
[New Thread 13236.0x374]
Breakpoint 1, main () at test.c:6
6 printf("Hello\n");
(gdb) step
_sigfe_puts () at sigfe.s:7019
7019 sigfe.s: No such file or directory.
(gdb)
7020 in sigfe.s
(gdb)
7023 in sigfe.s
(gdb)
_sigfe () at sigfe.s:19
19 in sigfe.s
(gdb)
20 in sigfe.s
(gdb)
21 in sigfe.s
.
.
.
(stops responding after various steps)
sigfe.s is a source file dynamically created during cygwin build.
It is present in the build tree:
$ find . -iname "*sigfe*"
./x86_64-unknown-cygwin/winsup/cygwin/sigfe.o
./x86_64-unknown-cygwin/winsup/cygwin/sigfe.s
and it seems the only file with such characteristics
$ find . -iname "*.s"
./x86_64-unknown-cygwin/winsup/cygwin/sigfe.s
In theory it should be included in the cygwin-debuginfo package
$ cygcheck -l cygwin-debuginfo | grep -i "s$"
/usr/src/debug/cygwin-2.8.1-0.1/newlib/libc/machine/x86_64/memcpy.S
/usr/src/debug/cygwin-2.8.1-0.1/newlib/libc/machine/x86_64/memset.S
/usr/src/debug/cygwin-2.8.1-0.1/newlib/libc/machine/x86_64/setjmp.S
You can highlight the issue on the cygwin mailing list.
https://cygwin.com/cygwin/lists.html

gdb in emacs hangs when issuing the 'q(uit)' command

I'm using emacs 24.5.1 under Mac Yosemite, in graphical mode and I'm trying to get gdb 7.11 working.
After starting gdb with 'gdb', I use 'r' to run a mini C++ code, consisting only of an empty main(), which exits normally. After it exits I can type 'r' again and the program will run and exit fine again. However, when I type 'q' to quit gdb, I get a newline without the (gdb) prompt, but gdb does not seem to have quit; It no longer responds to input, but when I try invoking gdb again, emacs tells me that 'this program is already being debugged'.
Current directory is ~/cpp/ppcpp/
GNU gdb (GDB) 7.11
Copyright (C) 2016 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-apple-darwin15.4.0".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from a.out...Reading symbols from /Users/mwisse/cpp/ppcpp/a.out.dSYM/Contents/Resources/DWARF/a.out...done.
done.
(gdb) r
Starting program: /Users/mwisse/cpp/ppcpp/a.out
[Inferior 1 (process 98675) exited normally]
(gdb) r
Starting program: /Users/mwisse/cpp/ppcpp/a.out
[Inferior 1 (process 98677) exited normally]
(gdb) q
...This is me typing something to show I can type anything here...
but no response.
Has anyone seen this before?
I didn't find out what caused the issue, but it went away after replacing my .emacs.d directory with the one mentioned here: http://tuhdo.github.io/emacs-for-proglang.html.