Ok, I'll add this patch to the random tree. I've modified the commit
message a bit since the speed advertisement of RDRAND is rather
pointless --- processes aren't generating session keys or long term
keys at a high rate, and programs can't count on /dev/random being
super fast and having unlimited entropy, since for most platforms and
even most x86 CPU's deployed in service today, this isn't true --- and
making your userspace program depond upon /dev/random in such a way
that it only works on Ivy Bridge CPU's might be good for Intel from a
vendor lock-in perspective, but it's really bad, non-portable
programming style.
Also, in the future arch_get_random_long() will almost certainly be
hooked up for other architectures, so putting an extended
advertisement for RDRAND really isn't appropriate.
- Ted
commit d2e7c96af1e54b507ae2a6a7dd2baf588417a7e5
Author: H. Peter Anvin <h...@linux.intel.com>
Date: Fri Jul 27 22:26:08 2012 -0400
random: mix in architectural randomness in extract_buf()
Mix in any architectural randomness in extract_buf() instead of
xfer_secondary_buf(). This allows us to mix in more architectural
randomness, and it also makes xfer_secondary_buf() faster, moving a
tiny bit of additional CPU overhead to process which is extracting the
randomness.
[ Commit description modified by tytso to remove an extended
advertisement for the RDRAND instruction. ]
Signed-off-by: H. Peter Anvin <h...@linux.intel.com>
Acked-by: Ingo Molnar <mi...@kernel.org>
Cc: DJ Johnston <dj.johns...@intel.com>
Signed-off-by: Theodore Ts'o <ty...@mit.edu>
Cc: sta...@vger.kernel.org
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