How to interpret backtrace addresses for debugging with GDB
backtrace, debug-backtrace, gdb
Solution
How to get exact line in disassemble for "+0x6f42a" and other addresses in GDB?
gdb /opt/server/libQtScript.so.4
(gdb) x/10i 0x6f42a
Usually you'll want instructions that executed before 0x6f42a, so you'll do this:
(gdb) x/20i 0x6f42a-30
Ignore the first few instructions: you could be starting disassembly from a middle of one. Usually the disassembly will re-synchronize after a few instructions, and will start showing correct instruction stream after that.
And what frame #0, without described module, means?
Your library has been stripped of symbols, so the only symbols you see (e.g. `_ZN12QScriptValue4callERKS_RK5QListIS_E`) are the externally-visible (aka exported) ones.
There are libQtScript.so.4.5.2.debug symbol file in QT_SOURCE/lib folder. So maybe I should copy .debug file near executable to get backtrace with full symbols?
GDB should load symbols from `libQtScript.so.4.5.2.debug` automatically if you set `debug-file-directory` to `$QT_SOURCE/lib`.
Update:
I ment getting backtrace with symbols without attaching GDB
I don't believe there is any support in `backtace_symbols()` for loading separate debuginfo files.
Problem
I am using backtrace() and backtrace_symbols() to output backtrace on SIGSEGV and other signals in format like this: ``` 0: [0xb750818] 1: /opt/server/libQtScript.so.4(+0x6f42a) [0xb782c42a] 2: /opt/server/libQtScript.so.4(+0x7bffc) [0xb7838ffc] 3: /opt/server/libQtScript.so.4(+0x86946) [0xb7843946] 4: /opt/server/libQtScript.so.4(+0x7c4bc) [0xb78394bc] 5: /opt/server/libQtScript.so.4(+0x86946) [0xb7843946] 6: /opt/server/libQtScript.so.4(+0x9603e) [0xb785303e] 7: /opt/server/libQtScript.so.4(_ZN12QScriptValue4callERKS_RK5QListIS_E+0x2e7) [0xb7891647] ``` In this particular case, frame #7 is fine for me, though frame 1-6 gives me some kind "+x" addresses. How to get exact line in disassemble for "+0x6f42a" and other addresses in GDB? And what frame #0, without described module, means?