Configuring for Linux and Large Files

32-bit systems running linux kernel version 2.4.0 or newer and glibc version 2.2.0 or newer can support files greater than 2 GBytes in size. This support is currently automaticly detected and enabled. We document the manual steps should the automatic detection not work for some reason.

The two macros _FILE_OFFSET_BITS=64 and _LARGEFILE64_SOURCE tell gnu libc it's ok to support large files on 32 bit platforms. The former changes the size of off_t (no need to change source. might affect interoperability with libraries compiled with a different size of off_t). The latter exposes the gnu libc functions open64(), write64(), read64(), etc. ROMIO does not make use of the 64 bit system calls directly at this time, but we add this flag for good measure.

If your linux system is relatively new, there is an excellent chance it is running kernel 2.4.0 or newer and glibc-2.2.0 or newer. Add the string

to your CFLAGS environment variable before runnint ./configure

Rob Latham 2016-08-01