Hi Patrick. On Sat, Nov 17, 2007 at 08:30:09PM +0100, Patrick McHardy (kaber@xxxxxxxxx) wrote: > These two patches add support for using the HIFN rng. Great! > The first patch improves the PLL initialization a bit by making the > reference clock configurable and its speed known to the driver, which > is needed to calculate the amount of time to wait between two RNG reads. > Since there is no way to find out the frequency reliably (especially for > the external clock), it adds some sane looking defaults and a module > parameter to override it. Suggestions how to improve this are welcome. I'm not sure it is possible to get it cleaner anyway. > 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(). > Running rngtest on the random number generator indicates that it works > properly, with an average failure ratio of about 1:1000 at ~2.5mbit. > > > drivers/crypto/hifn_795x.c | 158 +++++++++++++++++++++++++++++++++++++++++++- > 1 files changed, 156 insertions(+), 2 deletions(-) > > Patrick McHardy (2): > [HIFN]: Improve PLL initialization > [HIFN]: Add support for using the random number generator Ack both patches. Thanks a lot Patrick. -- Evgeniy Polyakov - 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
