static linking c libraries

[Eljay Love-Jensen]

Hi Israel,

Using your GCC cross-compiler from RedHat 9 to make a RedHat 7 executable 
should work.

You should double-check to make sure that you are linking against the 
RedHat 7 object code and libraries and using RedHat 7 system header files.

Regarding the legal implications:  I'm not a lawyer.  My understanding 
(which may be incorrect) is that the GCC Standard C Library and the GCC 
Standard C++ Library are covered by LGPL.  The LGPL is *not* GPL.  Non-GPL 
programs can link statically (or dynamically) to those LGPL protected 
libraries.

If you were using C instead of C++, it's very likely that your programs 
could be complied on RedHat 9 with the RedHat 9 native compiler, and moved 
to RedHat 7 and run without needing a cross-compiler.  The C ABI is the 
same on both platforms, if I'm not mistaken.

But the C++ ABI has changed between RedHat 7 and RedHat 9, if memory 
serves.  I wouldn't expect any RedHat 7 C++ dynamic libraries to work with 
a C++ application compiled on RedHat 9 by a RedHat 9 native compiler.

Also, if your application uses any RedHat 9 OS API (directly or indirectly) 
that is not present in RedHat 7 OS API, I'd expect the application to fail 
to run.

And finally, I believe that the preferred executable format for RedHat 9 is 
different from RedHat 7 (again, which is why a RedHat 7 cross-compiler is 
necessary).  RedHat 7 applications will (probably) be forward 
compatible/runnable on RedHat 9; but not necessarily vice versa.  Note: I 
may be mistaken on this one.

I ran into similar issues using GCC 2.95 on SunOS 5.8 (Solaris 8) with a 
target platform of SunOS 5.6 (Solaris 6).  Both platforms were using the 
self-same GCC 2.95; but differences in the OS API librt.so caused 
issues.  I had to make sure I was using the SunOS 5.6 header files when 
compiling on SunOS 5.8 -- that made sure I didn't inadvertently use an 
unsupported-on-5.6 API call.

Sincerely,
--Eljay