Hi Tony,  agree  the  -bexpall  is not good .

Do you have a good (/ better) solution  for the issue ,  do you use visibility 
attributes  in the C/C++   or  export-lists ?
Maybe someone from IBM could  comment on this too .

Best regards, Matthias


From: REIX, Tony <[email protected]>
Sent: Montag, 15. April 2019 16:18
To: Baesken, Matthias <[email protected]>; 
[email protected]; '[email protected]' 
<[email protected]>
Subject: RE: AIX : -bnorwexec linker flag


Hi



Maybe that the patch is good, but the original code, though working fine, is 
bad.





--- a/make/autoconf/flags-ldflags.m4



-    BASIC_LDFLAGS="-b64 -brtl -bnolibpath -bexpall -bernotok -btextpsize:64K \


On AIX, using -brtl and -bexpall is OK for fixing issues quick and dirty.
However, when building and delivering professional products, these options 
should be used only in last resort.

On AIX, the default is to NOT export all symbols. Instead, one should build the 
list of needed symbols and inform the linker with -bE and -bI linker options of 
the list of symbols that need to be exported/imported. That's more work, but 
it's the good way.

Using -bexpall means that all symbols contained in a library will be exported. 
Thus, an executable may want to load a symbol (like strcmp, which is first 
provided by the libc.a) from another library, breaking the upward 
compatibility. In addition, -bexpall creates performance issues. And also, 
sometimes, the linker explodes due to too many symbols.


As an example, the current versions of CMake and MariaDB for AIX make use of 
-bexpall (and, much worse, -expfull). We are changing the code of these 2 
packages in order to no more use -bexpall (nor -bexpfull).


Regards,

Tony

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