In a recent post that I now can't find, somebody mentioned a problem with some software compiling and working correctly with 64-bit but not with 32-bit. I have run into that problem with some non stock Slackware software I'm compiling.

The problem is not correctly detecting large files, specifically DVD ISO images. The problem occurs only in the 32-bit build but detects those files correctly in the 64-bit build.

Although the problem could be a system library not having proper support for 64 bit variables, files, etc., I suspect I'm doing something wrong that causes the build process to fail to recognize large files in 32-bit systems.

I use separate and clean build environments for both the 32-bit and 64-bit builds. No multilibs. No cross contamination (that I am aware). Other than this peculiar problem, everything otherwise builds and functions correctly.

I appreciate all ideas where to troubleshoot.

Thanks!

Not sure at all it be relevant but maybe have a look here.

In my 32-bit build log output I notice the following:

checking size of long... 4
checking size of char *... 4
checking size of size_t... 4
checking size of unsigned long... 4

In my 64-bit log:

checking size of long... 8
checking size of char *... 8
checking size of size_t... 8
checking size of unsigned long... 8

Is there a way to control those sizes?

When I use the terms 32-bit and 64-bit I am referring to the build environment and not my hardware. All builds are performed on the same AMD 64-bit dual core CPU system.

Why on earth do you think those values are wrong?

A 32 bit pointer (char *) is 4 bytes long. A 64 bit pointer (char *) is 8 bytes long. A long is a minimum of 4 bytes but can be larger if the runtime supports it.

Try to be more specific than this, please. It makes no sense what you are telling here.
What are you trying to compile. Why is this compilation trying to find a DVD ISO? What are the error messages?

Eric

Maybe you need to add "-D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64" in CFLAGS.