Why would gnu ld link order causes Signal 11 (SEGV) on startup?
- by Benoit
We are building a large application in C++ that includes the use of many (static) libraries.
We have a problem where the application crashes on startup with a Signal 11, before we even reach main.
After much debugging, we have observed that if we explicitly reference an object file so its link order is early, the program crashes on startup. If the file is referenced later (or not referenced at all), the program does not crash.
To be clear, there is NO code invoked directly from this object file. However, as it is C++, there might be static objects that do get constructed (it's a CORBA IDL generated file).
We use the -Wl,--start-group ... --end-group arguments to multi-pass link the symbols since the libraries are interdependent.
Here is a representation of what I mean. This is what the linker's object file order is:
Order 1 Order 2 Order 3
foo.o foo.o foo.o
... ... ...
main.o main.o main.o
crasher.o
libA.o libA.o libA.o
LibB.o LibB.o LibB.o
LibC.o LibC.o LibC.o
crasher.o
Results:
NO CRASH NO CRASH CRASH
Does any one have an idea why the linkage order has an effect on the crash?
It would be nice if we could force the crasher.o to link later, but we're really after an explanation.
Also, is there a way to force the linker to place crasher.o towards the end? Just to add to the fun, in actuality, crasher.o is part of a Library in the --start/--end-group.
