Re: Problem with random.c and PPC

Oliver Xymoron
2002-08-16T16:30:01Z

On Thu, Aug 15, 2002 at 06:50:32PM -0700, H. Peter Anvin wrote:
> Followup to: <20020815210449.GA26993@opus.bloom.county>
> By author: Tom Rini <trini@kernel.crashing.org>
> In newsgroup: linux.dev.kernel
> >
> > Ah, thanks. In that case, no. It doesn't look like the input-layer USB
> > keyboards contribute to entropy (but mice do), and I don't think the ADB
> > ones do. I'll take a crack at adding this to keyboards monday maybe.
> >
>
> Be careful... USB devices are *always* going to speak at the same
> place in the USB cycle... I believe that is 1 ms. Thus,
> submillisecond resolution is *not* random.

Currently not a problem for anyone except X86, as they'll only use HZ
resolution. But the same problem exists on regular mice and keyboards,
which are typically scanned for events at a fixed rate.

This is just the tip of the iceberg for problems with entropy
accounting. I've got some free time today, I'll try to clean up my
patches for this.

--
"Love the dolphins," she advised him. "Write by W.A.S.T.E.."