From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Borkmann Subject: Re: [PATCH v3 2/5] random,x86: Add arch_get_slow_rng_u64 Date: Thu, 17 Jul 2014 14:39:42 +0200 Message-ID: <53C7C40E.8070504@redhat.com> References: <5778e65d5ca52bebbaa023e177d863e44f098e96.1405546879.git.luto@amacapital.net> <53C6F5A9.80400@zytor.com> <53C703ED.2010605@zytor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Andy Lutomirski , kvm list , "Theodore Ts'o" , "linux-kernel@vger.kernel.org" , Kees Cook , X86 ML , Srivatsa Vaddagiri , Raghavendra K T , Gleb Natapov , Paolo Bonzini , Bandan Das , hannes@stressinduktion.org To: "H. Peter Anvin" Return-path: In-Reply-To: <53C703ED.2010605@zytor.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 07/17/2014 12:59 AM, H. Peter Anvin wrote: > On 07/16/2014 03:40 PM, Andy Lutomirski wrote: >> On Wed, Jul 16, 2014 at 3:13 PM, Andy Lutomirski wrote: >>> My personal preference is to defer this until some user shows up. I >>> think that even this would be too complicated for KASLR, which is the >>> only extremely early-boot user that I found. >>> >>> Hmm. Does the prandom stuff want to use this? >> >> prandom isn't even using rdrand. I'd suggest fixing this separately, >> or even just waiting until someone goes and deletes prandom. > > prandom is exactly the opposite; it is designed for when we need > possibly low quality random numbers very quickly. RDRAND is actually > too slow. Yep, prandom() is quite heavily used in the network stack where it's traded for speed.