From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752443Ab2G0OaV (ORCPT ); Fri, 27 Jul 2012 10:30:21 -0400 Received: from e37.co.us.ibm.com ([32.97.110.158]:42171 "EHLO e37.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751329Ab2G0OaT (ORCPT ); Fri, 27 Jul 2012 10:30:19 -0400 Date: Fri, 27 Jul 2012 09:29:21 -0500 From: Kent Yoder To: "H. Peter Anvin" Cc: James Morris , Peter Huewe , Bryan Freed , linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org Subject: Re: [GIT PULL] New TPM driver and features Message-ID: <20120727142921.GA28347@linux.vnet.ibm.com> References: <20120726143101.GA24237@linux.vnet.ibm.com> <5011BAB1.6060300@zytor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5011BAB1.6060300@zytor.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12072714-7408-0000-0000-0000072299ED Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Thu, Jul 26, 2012 at 02:46:25PM -0700, H. Peter Anvin wrote: > On 07/26/2012 07:31 AM, Kent Yoder wrote: > > hw_random: add support for the TPM chip as a hardware RNG source > > Could you clarify this? rngd (the user of /dev/hw_random) already > has support for the TPM... is this fundamentally different (e.g. can > it coexist with tcsd being in use at the same time)? These can coexist at the same time since /dev/tpm0 is only opened once from user-space (from tcsd) and this hwrng driver comes in through the kernel. There would be some amount of contention with the tpm, but its not likely to be noticable - grabbing rng data doesn't require any state in the tpm, like an auth session or key loading. Since the rngd support for the tpm requires trousers, this patch will be useful in places where you don't want to have to deploy the full TSS, like embedded and early boot. Kent > > -hpa > > -- > H. Peter Anvin, Intel Open Source Technology Center > I work for Intel. I don't speak on their behalf. >