> -----Original Message----- > From: Dan Carpenter [mailto:dan.carpenter@xxxxxxxxxx] > Sent: Tuesday, August 25, 2015 1:51 PM > To: Zhou, David(ChunMing) > Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx > Subject: Re: drm/amdgpu: implement cgs gpu memory callbacks > > 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; > } [DZ] oh, I understand your mean, with previous PAGE_SHIFT, I think it should be like 'b' in your example without truncates. Thanks, David Zhou > > regards, > dan carpenter _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
