> > could do intelligent interpolation about what the epoch is, so in 2039 > > if we get a low 32 bit time_t value, we assume epoch == 1, conversely if > > we see a high one, we assume epoch == 0. We could add epoch on the end > > of the syscalls and detect if it's not present and fill in an > > interpolated value. Interfaces which truly want 64 bit time_t would get > > it from epoch + 32 bit time_t. True sort of for the kernel (except you've got problems with file system compatibility and I believe stuff like NFS and that fact some file systems just break). > The main advantage that I see with 64-bit time_t is that a lot of user > space already works with it, because NetBSD and OpenBSD use this, and > all 64-bit Linux systems already work with this without changing the ABI. > If we want a POSIX extension to cover a new ABI, this would be the most > likely candidate. The main advantage IMHO of just using 64bit on 32bit boxes is getting it right. I'd go so far as to consider changing userspace time_t to be a struct. Yes it'll break lots of code but at least you'll know about it. (and for some other systems like 2BSD it's probably the least of evils because there isn't a 64bit type in the compiler!) > As mentioned earlier, between kernel and user space it's probably best > to avoid time_t and timeval completely and just use timespec64 or some > other safe type, but there has to be a way to port user space that relies > on time_t or timespec. This I think is bang on. We've already got lots of cases where we can't shoehorn useful info into syscalls due to time_t, including stuff like exposing accurate stamps in stat(). On an 8MHz 68000 not much happened in the same second, on a 32 core x86 it's a bit different. Alan -- 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
