From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Hutchings Subject: Re: PHC device sharing between PCI functions Date: Thu, 4 Jul 2013 19:19:05 +0100 Message-ID: <1372961945.1853.9.camel@bwh-desktop.uk.level5networks.com> References: <1372697768.2083.21.camel@bwh-desktop.uk.level5networks.com> <20130702142420.GC14630@netboy> <1372778262.1919.12.camel@bwh-desktop.uk.level5networks.com> <20130703183035.GA4446@netboy> <1372881153.1919.49.camel@bwh-desktop.uk.level5networks.com> <20130704053605.GC4457@netboy> <1372948466.1853.1.camel@bwh-desktop.uk.level5networks.com> <20130704155339.GA15214@netboy> <1372954878.1853.6.camel@bwh-desktop.uk.level5networks.com> <20130704173925.GA4429@netboy> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: linux-net-drivers , netdev , Laurence Evans To: Richard Cochran Return-path: Received: from webmail.solarflare.com ([12.187.104.25]:44391 "EHLO webmail.solarflare.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756855Ab3GDSTK (ORCPT ); Thu, 4 Jul 2013 14:19:10 -0400 In-Reply-To: <20130704173925.GA4429@netboy> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, 2013-07-04 at 19:39 +0200, Richard Cochran wrote: > On Thu, Jul 04, 2013 at 05:21:18PM +0100, Ben Hutchings wrote: > > > > But that is the opposite of what we're talking about. Say the card has, > > 16 functions resulting in net devices eth0-eth15, each of which can > > access the same physical clock. You said it's OK to have read-only > > aliases for a clock, so then there might be a writable /dev/ptp0 and > > read-only /dev/ptp1-ptp15. What is the proper association between net > > devices and clock devices? > > But the card doesn't have 16 plugs, or does it? No, but there can be multiple ports, and multiple functions per port. All sharing the same clock. > I understood you to have meant that the card has one physical plug, > shared between one host and fifteen guests. Or maybe I am total > confused. No, I am surely confused. > > Anyhow, if a host is multihomed, then ideally all of the interfaces > share one and the same clock. But, if the only purpose of the multiple > interfaces in the VM host is to assign them to VM guests, then I guess > it doesn't matter very much how they appear in the VM host. The functions that are intended to be assigned to guests will still appear and may have a driver bound to them in the host before they are assigned to guests. Ben. -- Ben Hutchings, Staff Engineer, Solarflare Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked.