I'm trying to automate a gdb session using the --command flag. I'm trying to set a breakpoint on a function in a shared library (the Unix equivalent of a DLL) . My cmds.gdb looks like this:
set args /home/shlomi/conf/bugs/kde/font-break.txt
b IA__FcFontMatch
r
However, I'm getting the following:
shlomi:~/progs/bugs-external/kde/font-breaking$ gdb --command=cmds.gdb...
GNU gdb 6.8-2mdv2009.0 (Mandriva Linux release 2009.0)
Copyright (C) 2008 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later
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 "i586-mandriva-linux-gnu"...
(no debugging symbols found)
Function "IA__FcFontMatch" not defined.
Make breakpoint pending on future shared library load? (y or [n]) [answered N; input not from terminal]
So it doesn't set the breakpoint after all. How can I make it default to answer "y" to set breakpoints on pending future shared library load?
I recall that I was able to do something, but cannot recall what.
Replying to myself, I'd like to give the answer that someone gave me on IRC:
(gdb) apropos pending
actions -- Specify the actions to be taken at a tracepoint
set breakpoint -- Breakpoint specific settings
set breakpoint pending -- Set debugger's behavior regarding pending breakpoints
show breakpoint -- Breakpoint specific settings
show breakpoint pending -- Show debugger's behavior regarding pending breakpoints
And so set breakpoint pending on does the trick; it is used in cmds.gdb like e.g.
set breakpoint pending on
break <source file name>:<line number>
OT: In terminal it would look like this to debug Caja in one line:
gdb -ex "set breakpoint pending on" -ex "break gdk_x_error" -ex run --args caja --sync
With no symbols.
objdump -t /lib/libacl.so
SYMBOL TABLE:
no symbols
objdump -T /lib/libacl.so
...
00002bd0 g DF .text 000000d0 ACL_1.0 acl_delete_entry
...
(gdb) break 0x0002bd0
(gdb) x/20i acl_delete_entry
0x2bd0 <acl_delete_entry>: stwu r1,-32(r1)
0x2bd4 <acl_delete_entry+4>: mflr r0
0x2bd8 <acl_delete_entry+8>: stw r29,20(r1)
0x2bdc <acl_delete_entry+12>: stw r30,24(r1)
0x2be0 <acl_delete_entry+16>: mr r29,r4
0x2be4 <acl_delete_entry+20>: li r4,28972
Related
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
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.
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
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.
Short question: Is there any support of D2 in gdb (I have gdb 7.2) ?
Long story: I compiled next little application ...
// file main.d
int glVar = 0xAAAAAAAA;
void main()
{
glVar = 0xBBBBBBBB;
}
... using command "dmd -gc -debug main.d";
then I load it to gdb and trying to debug it:
vnm#vnm:~/proj/d_gdb_test$ gdb main
GNU gdb (GDB) 7.2-ubuntu
Copyright (C) 2010 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later
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 "i686-linux-gnu".
For bug reporting instructions, please see:
...
Reading symbols from /home/vnm/proj/d_gbb_test/main...done.
(gdb) b main
Breakpoint 1 at 0x804b667
(gdb) r
Starting program: /home/vnm/proj/d_gbb_test/main
[Thread debugging using libthread_db enabled]
Breakpoint 1, 0x0804b667 in main ()
(gdb) info line
No line number information available.
(gdb) info variables glVar
All variables matching regular expression "glVar":
File main.d:
int _D4main5glVari;
Why gdb can't show line information and why it shows symbols in mangled form ? Is this software issues or I'm doing something wrong ?
gdb has support for D starting with version 7.2. So, you can debug D programs with gdb 7.2.
Now, that doesn't mean that support is perfect - far from it in fact. For instance, I'm not sure that you can get it to print strings properly. And it's not at all surprising if it doesn't demangle D symbols. So, it works, but it's far from perfect.