On Thu, 2 Apr 2009, [email protected] wrote:
>
> glibc entriely and use a syscall prototype which works without
> arch-specific wrappers inside the kernel: The offset argument is
> explicitly split into two 32bit values.
Grr. That may make sense on 32-bit architectures, but makes no sense
what-so-ever on 64-bit ones.
Why not just say that it's two "unsigned long" arguments, and split it by
"sizeof unsigned long". And then, on 64-bit architectures, the high bits
can be ignored. You can even get gcc to optimize it all away by doing
something like
#define HALF_LONG (BITS_IN_LONG / 2)
offset = (((loff_t)high << HALF_LONG) << HALF_LONG) | low;
and then gcc should automaticaly notice that shifting up that way is just
a fancy way of saying "0", and ignore the high bits.
How married are people to this crazy 2x "32 bits" model?
Linus
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