On Fri, Aug 19, 2016 at 10:20:18AM -0700, H. Peter Anvin wrote: > On 08/18/16 22:56, Herbert Xu wrote: > > On Thu, Aug 18, 2016 at 10:49:47PM -0400, Theodore Ts'o wrote: > >> > >> That really depends on the system. We can't assume that people are > >> using systems with a 100Hz clock interrupt. More often than not > >> people are using tickless kernels these days. That's actually the > >> problem with changing /dev/urandom to block until things are > >> initialized. > > > > Couldn't we disable tickless until urandom has been seeded? In fact > > perhaps we should accelerate the timer interrupt rate until it has > > been seeded? > > > > The biggest problem there is that the timer interrupt adds *no* entropy > unless there is a source of asynchronicity in the system. On PCs, > traditionally the timer has been run from a completely different crystal > (14.31818 MHz) than the CPU, which is the ideal situation, but if they > are run off the same crystal and run in lockstep, there is very little > if anything there. On some systems, the timer may even *be* the only > source of time, and the entropy truly is zero. Sure, but that's orthorgonal to what Ted was talking about above. Thanks, -- Email: Herbert Xu <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
