From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by dpdk.org (Postfix) with ESMTP id 7AD3BB16F for ; Fri, 13 Jun 2014 20:13:51 +0200 (CEST) Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s5DIE5Rj025004 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 13 Jun 2014 14:14:05 -0400 Received: from x220.localdomain ([10.3.113.19]) by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with SMTP id s5DIE3fS016015; Fri, 13 Jun 2014 14:14:03 -0400 Date: Fri, 13 Jun 2014 11:14:03 -0700 From: Chris Wright To: "Richardson, Bruce" Message-ID: <20140613181403.GT1384@x220.localdomain> References: <20140606235028.189345212@networkplumber.org> <2240300.rVk2eNDOWK@xps13> <20140613102440.19537123@nehalam.linuxnetplumber.net> <20140613175137.GS1384@x220.localdomain> <59AF69C657FD0841A61C55336867B5B01AA36117@IRSMSX103.ger.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <59AF69C657FD0841A61C55336867B5B01AA36117@IRSMSX103.ger.corp.intel.com> User-Agent: Mutt/1.5.21+63 (2f2ebc24920d) (2011-07-01) X-Scanned-By: MIMEDefang 2.68 on 10.5.11.23 Cc: "dev@dpdk.org" Subject: Re: [dpdk-dev] [PATCH] igb_uio: cap max VFs at 7 to reserve one for PF X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 13 Jun 2014 18:13:51 -0000 * Richardson, Bruce (bruce.richardson@intel.com) wrote: > > > > -----Original Message----- > > From: Chris Wright [mailto:chrisw@redhat.com] > > Sent: Friday, June 13, 2014 10:52 AM > > To: Richardson, Bruce; Stephen Hemminger > > Cc: Thomas Monjalon; dev@dpdk.org > > Subject: [PATCH] igb_uio: cap max VFs at 7 to reserve one for PF > > > > To keep from confusing users, cap max VFs at 7, despite PCI SR-IOV config > > space showing a max of 8. This reserves a queue pair for the PF. > > > > This issue was cited here: > > > > http://dpdk.org/ml/archives/dev/2014-April/001832.html > > > > Cc: Bruce Richardson > > Cc: Stephen Hemminger > > Signed-off-by: Chris Wright > > --- > > > > This is what Linux kernel driver does. I have only > > compile tested it. Stephen sending to you and Bruce > > in case you want to Ack and add to your current queue. > > > > Sorry, NAK - at least for this implementation. Oh, that's fine. > Hardcoding this to 7 is a bad idea, as the actual max number of VFs supported will depend on the actual hardware used. For someone using an 82599, they can have up to 64 VFs, or 63+PF, so limiting so 7 in that case is a major reduction in capability. What might work there is querying the max number of VFs and limiting to max - 1. But this is igb_uio, not 82599 (ixgbe). > However, even with that, I would suggest that any limit should be possible to override. It's entirely possible that someone max actually want to reserve the full number of VFs, either because they don't want to use the NIC on the host at all, or because they are happy to use a VF on the host instead. Module parameter to allow override might work - and information on it could be added to the error message when we limit the VFs inside the driver. It's been a while since I've looked at this, but my recollection is the PF must be there (basic mailbox handling, for example). Would you rather a simple warning message as a hint?