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#1 2016-09-29 07:11:05
- nemo19
- Member
- Registered: 2016-09-29
- Posts: 2
[Solved] Qt app running fine on Ubuntu segfaults immediately
Hey guys,
I've got a problem running a Qt application and getting somewhat desperate. I'm part of the software engineering team developing the program and need to run and test it. I was able to do so up to now using Ubuntu, but not using Arch.
When I got my PC it was running a fresh install of Ubuntu 16.04LTS x64. I installed qt-sdk, vtk and some other required libraries. Worked on the program, compiled it, ran it. All worked fine.
Then I replaced Ubuntu by a fresh Arch install (which is what I'm using at home), installed qt5-*, vtk and the other libraries. Compiled the program, started it, and it immediately said
Segmentation fault (core dumped) Running in gdb gives
Program received signal SIGSEGV, Segmentation fault.
0x00007fffee46bb74 in ?? () from /usr/lib/libQtGui.so.4
(gdb) bt
#0 0x00007fffee46bb74 in ?? () from /usr/lib/libQtGui.so.4
#1 0x00007ffff7de94fa in call_init.part () from /lib64/ld-linux-x86-64.so.2
#2 0x00007ffff7de960b in _dl_init () from /lib64/ld-linux-x86-64.so.2
#3 0x00007ffff7ddadaa in _dl_start_user () from /lib64/ld-linux-x86-64.so.2
#4 0x0000000000000001 in ?? ()
#5 0x00007fffffffe455 in ?? ()
#6 0x0000000000000000 in ?? ()I added the qt-debug repo to pacman, replaced qt5-* by qt5-*-debug, set CONFIG += debug in the PRO file and all the g++ debug flags, but got the same output. Then I set a breakpoint at the first line of main(), which is empty. It still segfaults before reaching the breakpoint. Running in QtCreator Debug mode pops up the message
The inferior stopped because it received a signal from the operating system.
Signal name : SIGSEGV
Signal meaning : Segmentation faultand prints out a bunch of assembler code
0x7fffee581b60 b4 00 mov $0x0,%ah
0x7fffee581b62 00 00 add %al,(%rax)
0x7fffee581b64 00 00 add %al,(%rax)
0x7fffee581b66 c6 05 a3 6f b4 00 00 movb $0x0,0xb46fa3(%rip) # 0x7fffef0c8b10
0x7fffee581b6d 48 89 05 a4 6f b4 00 mov %rax,0xb46fa4(%rip) # 0x7fffef0c8b18
0x7fffee581b74 f0 ff 00 lock incl (%rax)
0x7fffee581b77 0f 95 c2 setne %dl
0x7fffee581b7a f0 ff 0f lock decl (%rdi)
0x7fffee581b7d 0f 95 c0 setne %al
0x7fffee581b80 84 c0 test %al,%al
0x7fffee581b82 74 1e je 0x7fffee581ba2
0x7fffee581b84 48 8d 15 f5 19 b4 00 lea 0xb419f5(%rip),%rdx # 0x7fffef0c3580
0x7fffee581b8b 48 8d 35 6e 6f b4 00 lea 0xb46f6e(%rip),%rsi # 0x7fffef0c8b00
0x7fffee581b92 48 8d 3d c7 d5 1a 00 lea 0x1ad5c7(%rip),%rdi # 0x7fffee72f160
0x7fffee581b99 48 83 c4 08 add $0x8,%rsp
0x7fffee581b9d e9 5e 5d ff ff jmpq 0x7fffee577900 <__cxa_atexit@plt>
0x7fffee581ba2 e8 69 b4 ff ff callq 0x7fffee57d010 <_ZN7QString4freeEPNS_4DataE@plt>
0x7fffee581ba7 eb db jmp 0x7fffee581b84
0x7fffee581ba9 0f 1f 80 00 00 00 00 nopl 0x0(%rax)
0x7fffee581bb0 48 83 ec 08 sub $0x8,%rsp
0x7fffee581bb4 8b 05 92 6f b4 00 mov 0xb46f92(%rip),%eax # 0x7fffef0c8b4c
0x7fffee581bba 85 c0 test %eax,%eax
0x7fffee581bbc 75 16 jne 0x7fffee581bd4
0x7fffee581bbe 48 8d 3d d9 30 6d 00 lea 0x6d30d9(%rip),%rdi # 0x7fffeec54c9e
0x7fffee581bc5 48 83 ce ff or $0xffffffffffffffff,%rsi
0x7fffee581bc9 e8 d2 b4 1d 00 callq 0x7fffee75d0a0
0x7fffee581bce 89 05 78 6f b4 00 mov %eax,0xb46f78(%rip) # 0x7fffef0c8b4c
0x7fffee581bd4 48 8d 3d c3 30 6d 00 lea 0x6d30c3(%rip),%rdi # 0x7fffeec54c9ePlease let me know if you have any ideas as to why the same program compiles fine on both Ubuntu and Arch, but runs only on Ubuntu, and how I can get the debugging symbols to show up.
Google returned only very few results which did not help at all.
Last edited by nemo19 (2016-09-29 10:31:17)
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#2 2016-09-29 09:41:20
- Lone_Wolf
- Administrator
- From: Netherlands, Europe
- Registered: 2005-10-04
- Posts: 13,655
Re: [Solved] Qt app running fine on Ubuntu segfaults immediately
# pacman -Fyo /usr/lib/libQtGui.so.4
:: Synchronizing package databases...
core 655.0 KiB 7.35M/s 00:00 [#############################################] 100%
extra 7.3 MiB 6.20M/s 00:01 [#############################################] 100%
community 14.3 MiB 5.69M/s 00:03 [#############################################] 100%
multilib 298.7 KiB 5.12M/s 00:00 [#############################################] 100%
llvm-svn 7.6 KiB 0.00B/s 00:00 [#############################################] 100%
LoneVVolf is up to date
usr/lib/libQtGui.so.4 is owned by extra/qt4 4.8.7-9
# On Arch Linux libQtGui.so* is used exclusively for Qt4 , Qt5 uses libQt5Gui.so* .
Maybe ubuntu uses a different mechanism to distinguish between Qt4 & Qt5 .
Last edited by Lone_Wolf (2016-09-29 09:42:02)
Disliking systemd intensely, but not satisfied with alternatives so focusing on taming systemd.
clean chroot building not flexible enough ?
Try clean chroot manager by graysky
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#3 2016-09-29 10:29:46
- nemo19
- Member
- Registered: 2016-09-29
- Posts: 2
Re: [Solved] Qt app running fine on Ubuntu segfaults immediately
Thank you, that helped a lot.
I had just figured out that the segfault was caused by including a matching header/source file pair in the build. When excluding it everything worked fine. Thanks to you I checked with ldd which revealed, that when building without the files only libQt5Gui.so.5 is used, but when including them libQt5Gui.so.5 AND libQtGui.so.4 are used.
So far I have no idea how that is possible or why that happens (and why not on Ubuntu), but at least I know where to look.
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