On Tue, Aug 25, 2015 at 02:07:21AM +0000, Zhou, David(ChunMing) wrote:
> >and can the shift actually
> > wrap?
> [DZ] of course, adding shift wrap is better. fpfn/lpfn is page number, so <<PAGE_SHIFT is to convert to memory size.
By "Shift wrap" I meant how you shift beyond the end of a 32bit number
and it truncates, or if it's signed then it can wrap around (it's
undefined actually, I probably should use a different word?).
int main(void)
{
unsigned long long a = 0xf0000000U << 12;
unsigned long long b = 0xf0000000ULL << 12;
printf("%llx %llx\n", a, b);
return 0;
}
regards,
dan carpenter
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