Am Mittwoch, 4. Juli 2018, 08:10:35 CEST schrieb Vinod: Hi Vinod, > On 04-07-18, 09:40, Vinod wrote: > > Hi Stephan, > > > > On 03-07-18, 15:28, Stephan Mueller wrote: > > > Am Dienstag, 3. Juli 2018, 08:04:31 CEST schrieb Vinod Koul: > > > > +static int qcom_rng_read(struct qcom_rng *rng, void *data, size_t > > > > max) > > > > +{ > > > > + size_t currsize = 0; > > > > + u32 *retdata = data; > > > > > > How can you be sure that this cast is appropriate? I.e. how is it > > > guaranteed that data is 4-byte aligned? > > > > While reading we check the alignment: > > /* make sure we stay on 32bit boundary */ > > if ((max - currsize) < WORD_SZ) > > > > break; I am not sure I follow your argument. You cast a void (or u8 pointer into u32: + u32 *retdata = data; You use it: + *retdata++ = val; Followed by your check. What I mean is that the initial cast and then the subsequent write operation is only guaranteed to work if the initial pointer is alighed on a 4 byte boundary. However, since it is an u8 pointer, it is not guaranteed to be aligned. So, I guess you want to use memcpy (at least if it is not aligned). Ciao Stephan