Hi Kuan-Wei, > Several parts of the kernel contain redundant implementations of parity > calculations for 32-bit and 64-bit values. Introduces generic > parity32() and parity64() helpers in bitops.h, providing a standardized > and optimized implementation. More so than __builtin_parity() ? I'm all for reducing the duplication, but the compiler may well have a better parity approach than the xor-folding implementation here. Looks like we can get this to two instructions on powerpc64, for example. Cheers, Jeremy