Hoy there ! This may have been discussed earlier (I have some vague memories...) but I just hit a problem with that again (Mark: hint, it's in hdparm's fallocate) so I'd like a bit of a refresh here on what is the "right thing" to do... So some syscalls want a 64-bit argument. Let's take fallocate() as our example. So we already know that we have to be extra careful since some 32-bit arch will pass this into 2 registers (or stack slots) which need to be aligned, and so we tend to already take care of making sure that the said 64-bit argument is either defined as 2x32-bit arguments, or defined as 1x64 bit argument aligned to 2x32-bit in the argument list. So far so good... The problem is when user space tries to use the same trick for calling those functions using glibc-provided syscall() function. In this example, hdparm does: err = syscall(SYS_fallocate, fd, mode, offset, len); With "offset" being a 64-bit argument. This will break because the first argument to syscall now shifts everything by one register, which breaks the register pair alignment (and I suppose archs with stack based calling convention can have similar alignment issues even if x86 doesn't). Ulrich, Steven, shouldn't we have glibc's syscall() take a long long as it's first argument to correct that ? Either that or making it some kind of macro wrapper around a __syscall(int dummy, int sysno, ...) ? As it is, any 32-bit app using syscall() on any of the syscalls that takes 64-bit arguments will be broken, unless the app itself breaks up the argument, but the the order of the hi and lo part is different between BE and LE architectures ;-) So is there a more "correct" solution than another here ? Should powerpc glibc be fixed at least so that syscall() keeps the alignment ? Cheers, Ben. -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html