Re: [PATCH] (0/4) Entropy accounting fixes

Oliver Xymoron (oxymoron@waste.org)
Sun, 18 Aug 2002 10:08:31 -0500


On Sun, Aug 18, 2002 at 11:30:05AM +0100, Alan Cox wrote:
>
> Its probably true there are low bits of randomness available from such
> sources providing we know the machine has a tsc, unless the I/O APIC is
> clocked at a divider of the processor clock in which case our current
> behaviour is probably much saner.

I actually looked at this a bit for embedded applications - there's a
technique for pulling entropy from free-running clock skew.

Unfortunately with modern chipsets, just about all clocks are
generated from a single source these days. This is even true in the
non-x86 world now. Any extra clocks you have are likely to be out in
peripheral-land and too slow (serial port) or too inaccessible (VGA
dot clocks) to be interesting.

> With modern systems that have real RNG's its a non issue.

Thankfully.

-- 
 "Love the dolphins," she advised him. "Write by W.A.S.T.E.." 
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/