When Itanium was newborn, HP enlisted my employer, Progeny, to help port applications to ia64 Linux.
Despite the fact that 64-bit Linux had been running successfully on DEC Alpha systems for years, we ran into no end of difficulty because pointers were truncated all over the place, which apparently hadn't mattered on Alpha systems.
It seems like it must have been an Endian issue, but after 20 years my memories are basically toast. I just know nearly every bug we found was pointer truncation.
Despite the fact that 64-bit Linux had been running successfully on DEC Alpha systems for years, we ran into no end of difficulty because pointers were truncated all over the place, which apparently hadn't mattered on Alpha systems.
It seems like it must have been an Endian issue, but after 20 years my memories are basically toast. I just know nearly every bug we found was pointer truncation.