[PATCH] powerpc: Use hardware RNG for arch_get_random_seed_* not arch_get_random_*

Michael Ellerman mpe at ellerman.id.au
Fri Jul 17 14:44:35 AEST 2015

On Thu, 2015-07-16 at 22:12 +1000, Paul Mackerras wrote:
> The hardware RNG on POWER8 and POWER7+ can be relatively slow, since
> it can only supply one 64-bit value per microsecond.  Currently we
> read it in arch_get_random_long(), but that slows down reading from
> /dev/urandom since the code in random.c calls arch_get_random_long()
> for every longword read from /dev/urandom.
> Since the hardware RNG supplies high-quality entropy on every read, it
> matches the semantics of arch_get_random_seed_long() better than those
> of arch_get_random_long().  Therefore this commit makes the code use
> the hardware RNG only for arch_get_random_seed_{long,int} and not for
> arch_get_random_{long,int}.
> Signed-off-by: Paul Mackerras <paulus at samba.org>

Yep seems sensible.

Can you resend and CC some of the random folks, just in case they care.

eg: tytso at mit.edu, keescook at chromium.org, hpa at linux.intel.com.


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