Re: Collecting entropy from device_attach() times.

2012-10-03 Thread Dag-Erling Smørgrav
RW writes: > Yes, getting a monotonically increasing value from binuptime() is > simple, but the xor issue is secondary to the problem I was referring > to when I quoted the arm code for get_cyclecount(). BTW, I just checked - the code you quoted does not exist / no longer exists anywhere in the

Re: Collecting entropy from device_attach() times.

2012-10-03 Thread RW
On Wed, 03 Oct 2012 11:32:45 +0200 Dag-Erling Smørgrav wrote: > RW writes: > > It doesn't compute it in a weird way for amd64 and most i386 > > systems. Where possible, get_cyclecount is just a wrapper for > > rdtsc, which I think it will be for all the systems you quoted > > (with the possible e

Re: Collecting entropy from device_attach() times.

2012-10-03 Thread RW
On Wed, 03 Oct 2012 13:42:03 +0200 Dag-Erling Smørgrav wrote: > RW writes: > > As I pointed-out before if you use binuptime() you cant use entropy > > estimation based on bit-shifting time differences. > > Forgot to answer this: yes you can. The last time I raised the > issue, I also provided s

Re: Collecting entropy from device_attach() times.

2012-10-03 Thread Dag-Erling Smørgrav
RW writes: > As I pointed-out before if you use binuptime() you cant use entropy > estimation based on bit-shifting time differences. Forgot to answer this: yes you can. The last time I raised the issue, I also provided sample code for reimplementing get_cyclecount() in terms of binuptime(). Ba

Re: Collecting entropy from device_attach() times.

2012-10-03 Thread Dag-Erling Smørgrav
RW writes: > It doesn't compute it in a weird way for amd64 and most i386 systems. > Where possible, get_cyclecount is just a wrapper for rdtsc, which I > think it will be for all the systems you quoted (with the possible > exception of virtualbox). No. All the machines I tested it on had TSCs,