From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Tue, 1 Oct 2013 19:23:20 +1000 From: Paul Mackerras To: Gleb Natapov Subject: Re: [PATCH 3/3] KVM: PPC: Book3S: Add support for hwrng found on some powernv systems Message-ID: <20131001092320.GA2000@iris.ozlabs.ibm.com> References: <1380177066-3835-1-git-send-email-michael@ellerman.id.au> <1380177066-3835-3-git-send-email-michael@ellerman.id.au> <5243F933.7000907@redhat.com> <20131001083426.GB27484@concordia> <20131001083908.GA17294@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20131001083908.GA17294@redhat.com> Cc: tytso@mit.edu, kvm@vger.kernel.org, linuxppc-dev@ozlabs.org, agraf@suse.de, kvm-ppc@vger.kernel.org, linux-kernel@vger.kernel.org, herbert@gondor.hengli.com.au, mpm@selenic.com, Paolo Bonzini List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Tue, Oct 01, 2013 at 11:39:08AM +0300, Gleb Natapov wrote: > On Tue, Oct 01, 2013 at 06:34:26PM +1000, Michael Ellerman wrote: > > On Thu, Sep 26, 2013 at 11:06:59AM +0200, Paolo Bonzini wrote: > > > Il 26/09/2013 08:31, Michael Ellerman ha scritto: > > > > Some powernv systems include a hwrng. Guests can access it via the > > > > H_RANDOM hcall. > > > > > > Is there any reason to do this in the kernel? > > > > It's less code, and it's faster :) > > > > > It does not have to be a particularly fast path; > > > > Sure, but do we have to make it slow on purpose? > > > We do not put non performance critical devices into the kernel. It's not a device, it's a single hypercall, specified by PAPR, which is the moral equivalent of x86's RDRAND. Paul.