Re: [xml] 32bit libraries in 64bit Linux machine

[Rick Jones <rick jones2 hp com>]

Ricky Marek wrote:
> Hello,
>
> The project I'm working now has migrated from a 32bit Linux machine to a 
> 64bit Linux machine, with the excuse that it will run faster.

Well, unless the 64-bit Linux machine is inherently faster (clock rate, 
memory latency) it is unlikely that just being 64-bit will make things 
faster.

For the platform(s) where 64-bit does run faster it is generally because 
the code has been recompiled for 64-bit to get one or more of the following:

*) more registers

*) application access to more memory at one time.

(Of course this is braod handwaving)

What sort of system is this?

> The code I wrote is called by the a CAD simulator (ncsim) as a dynamic 
> library, this code calls the XML library (which is installed as a 64bit 
> library by default on the Linux Machine).
>
>  Under a 32bit Linux machine all goes as required, but when we try to 
> run it on a 64bit machine, problems start to pop up.
>
> - My code needs to be compiled as 32bit in order to run (I'm not sure if 
> this is a ncsim limitation or setup limitation)

Might want to see if that limitation can be removed.  At the very least, 
in this day and age you should probably make sure your code is at least 
64-bit "clean" even if you are still compiling 32-bit.  Different 
compilers have different options to tell you about the 64-bit 
cleanliness of your code, so best to check their manpages and/or manuals.

> - My code calls the installed XML libraries and fail to run due that the 
> libraries encountered are 62bit.
>
> Questions:
>
> - How can I determine if the installed XML library is 32 or 64 bit?

Try running the "file" command against it and see what it says.

> - How can I make the ncsim load a 32bit XML library? ( via 
> LD_LIBRARY_PATH environment variable?)

You might be able to do that, but better would be to link more directly 
against the 32-bit library, once you have determined that there is one 
on the system.

> - What are the gcc flags to compile code as 32bit on a 64bit machine? (I 
> want to make sure I'm using the correct flags)

That one should be in the manpage :)

rick jones