QT5.7 libraries built with GCC-4.9.1 but linked with older libstdc++?
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Hi,
I built QT-5.7 sources on CentOS 6.5 64-bit and then compared with the binaries that is bundled in the QT-5.7 offline installer. I found that the QT5 libraries (specially webengine libs) that I built had a dependency on libstdc++.so that was installed on my machine when I built GCC-4.9.1. But the libraries that is bundled in the installer is actually linked with older libstdc++. How is it possible to do that?
Installer lib:
$ strings -a Qt570_installer/5.7/gcc_64/lib/libQt5WebEngineCore.so | grep GCC:
GCC: (GNU) 4.4.7 20120313 (Red Hat 4.4.7-9)
GCC: (GNU) 4.9.1 20140922 (Red Hat 4.9.1-10)$ strings -a Qt570_installer/5.7/gcc_64/lib/libQt5WebEngineCore.so | grep ^CXXABI
CXXABI_1.3$ strings -a Qt570_installer/5.7/gcc_64/lib/libQt5WebEngineCore.so | grep ^GLIBCXX
GLIBCXX_3.4.11
GLIBCXX_3.4.10
GLIBCXX_3.4.9
GLIBCXX_3.4My Build:
$ strings -a Qt-5.7.0/lib/libQt5WebEngineCore.so | grep GCC:
GCC: (GNU) 4.4.7 20120313 (Red Hat 4.4.7-16)
GCC: (GNU) 4.9.1$ strings -a Qt-5.7.0/lib/libQt5WebEngineCore.so | grep ^CXXABI
CXXABI_1.3.5
CXXABI_1.3$ strings -a Qt-5.7.0/lib/libQt5WebEngineCore.so | grep ^GLIBCXX
GLIBCXX_3.4.20
GLIBCXX_3.4.14
GLIBCXX_3.4.10
GLIBCXX_3.4.18
GLIBCXX_3.4.15
GLIBCXX_3.4.9
GLIBCXX_3.4.11
GLIBCXX_3.4So, because of this difference, I see that the resulting application needed libstdc++.so from the gcc-4.9.1 on the target machine. The same was not needed when I built the application using the QT offline installer.
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Hi,
I really would like to know this how QT guys compile the QT source with higher version of GCC but link with lower STDC++ library. I'm trying to build QT5.7.1 on CentOS 6 32bit and the app crashes and gdb is not showing enough information but it seems it has to do with system libs like libc.so, libm.so
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To give an idea on how I configured QT on CentOS 6 32bit:
- Since system comes with GCC-4.4.7, I configured GCC-4.9.1 sources and installed in /usr/local/. I then set the PATH and LD_LIBRARY_PATH to include the GCC-4.9.1 bin and lib paths resp and configured QT.
My app crashes and here is the backtrace:
(gdb) bt
#0 0x00003402 in ?? ()
#1 0x00f19ac7 in __fmaf_ifunc () at ../sysdeps/i386/i686/multiarch/s_fmaf.c:30
#2 0x00abff6c in elf_machine_rel (scope=0xb77b2a40, reloc_mode=1, consider_profiling=0) at ../sysdeps/i386/dl-machine.h:351
#3 elf_dynamic_do_rel (scope=0xb77b2a40, reloc_mode=1, consider_profiling=0) at do-rel.h:120
#4 _dl_relocate_object (scope=0xb77b2a40, reloc_mode=1, consider_profiling=0) at dl-reloc.c:268
#5 0x00ab69df in dl_main (phdr=0x8048034, phnum=8, user_entry=0xbf9b92ec, auxv=0xbf9b93f8) at rtld.c:2262
#6 0x00ac8c11 in _dl_sysdep_start (start_argptr=0xbf9b9350, dl_main=0xab5630 <dl_main>) at ../elf/dl-sysdep.c:244
#7 0x00ab4273 in _dl_start_final (arg=0xbf9b9350) at rtld.c:335
#8 _dl_start (arg=0xbf9b9350) at rtld.c:561
#9 0x00ab3857 in _start () from /lib/ld-2.12.so
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@SandeepT Do you set LD_LIBRARY_PATH variable before starting your app, so it points to /usr/local/... ?
If not then I guess the loader loads older libs from /usr which are built with the older compiler.
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No, I set LD_LIBRARY_PATH and PATH variables before I configure QT so that it picks the correct GCC.
PATH=/usr/local/gcc-4.9.1/bin:$PATH
LD_LIBRARY_PATH=/usr/local/gcc-4.9.1/lib:$PATH
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@SandeepT Then try to set LD_LIBRARY_PATH before starting your app, so the loader picks up correct libraries.
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yes, I do set LD_LIBRARY_PATH before I run my app. I basically need to know two things:
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Why the QT libraries that I built depends on libstdc++ that comes with gcc-4.9.1 and the libraries bundled in the QT offline installer do not, even though the compiler version used in both the cases is 4.9.1 ?
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Which libraries from GCC should I bundle along with my app? libstdc++.so, libgcc_s.so?
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- As far as I know Qt for Linux is built on RedHat Linux, that could explain
- You should bundle libraries which are needed by your app, you can find out which those are calling
ldd YOUR_APP
