On Sat, Nov 17, 2007 at 07:53:25PM +0000, Evgeniy Polyakov wrote: > > > The second patch adds hw_random support. The ugly part is finding out > > when to allow reads from the RNG. It currently translates the public > > key engine clock cycles to CPU cycles based on a 4GHz CPU and uses > > get_cycles(). The problems with this are obvious, it only works on CPUs > > that actually have some kind of cycle counter, has problems with > > unsynchronized TSCs and the 4GHz assumption is not very nice either, > > but I was reluctant to use ktime for this since it seems rather > > expensive to call ktime_get once per 4 bytes of random. Suggestion > > for improvement of this are also welcome :) > > It will not work on arm, but I'm not sure this is relevant... > Another option is to directly access xtime without all wrappers in the > ktime_get(). Is it really that bad? You're most likely going to be spinning for 10us in udelay() or worse busy-looping anyway so I'm not sure if we need to worry about that overhead too much. Otherwise these patches look pretty nice to me. Thanks Patrick! Cheers, -- Visit Openswan at http://www.openswan.org/ Email: Herbert Xu ~{PmV>HI~} <herbert@xxxxxxxxxxxxxxxxxxx> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt - To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
