Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754959AbZIAOXo (ORCPT ); Tue, 1 Sep 2009 10:23:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754926AbZIAOXo (ORCPT ); Tue, 1 Sep 2009 10:23:44 -0400 Received: from cantor2.suse.de ([195.135.220.15]:35245 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754921AbZIAOXn (ORCPT ); Tue, 1 Sep 2009 10:23:43 -0400 Subject: Re: [PATCH] SCSI driver for VMware's virtual HBA. From: James Bottomley To: akataria@vmware.com Cc: Robert Love , Randy Dunlap , Mike Christie , "linux-scsi@vger.kernel.org" , LKML , Andrew Morton , Dmitry Torokhov , Rolf Eike Beer , Maxime Austruy , Bhavesh Davda In-Reply-To: <1251755593.16169.51.camel@ank32.eng.vmware.com> References: <1251415060.16297.58.camel@ank32.eng.vmware.com> <1251739735.16169.20.camel@ank32.eng.vmware.com> <1251741624.18828.83.camel@mulgrave.site> <1251755593.16169.51.camel@ank32.eng.vmware.com> Content-Type: text/plain Date: Tue, 01 Sep 2009 09:23:32 -0500 Message-Id: <1251815012.3864.55.camel@mulgrave.site> Mime-Version: 1.0 X-Mailer: Evolution 2.24.1.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1653 Lines: 43 On Mon, 2009-08-31 at 14:53 -0700, Alok Kataria wrote: > Hi James, > > Thanks for your comments. > > On Mon, 2009-08-31 at 11:00 -0700, James Bottomley wrote: > > On Mon, 2009-08-31 at 10:28 -0700, Alok Kataria wrote: > > > VMware PVSCSI driver - v2. > > > > OK, so the first thing that springs to mind is that we already have one > > of these things: the ibmvscsi ... is there no way we can share code > > between this and the other PV drivers? > > I took a quick look at the ibmvscsi driver, and there are lot of > differences between the two, mainly the ABI that is shared between the > hypervisor and driver differ. Well, that's pretty abstractable, surely? However, there is an interesting question of what the best hypervisor interface actually is. > Also the ibmvscsi driver seems to offer a > lot of other features as well, like the SRP. SRP is the protocol transfer abstraction. It's just a way of packaging up SCSI commands for transfer over a DMA protocol (OK, so it was envisaged that the DMA protocol would be RDMA, but a hypervisor interface is also a DMA protocol). > The pvscsi driver is a simple SCSI adapter driver and is basically no > different than any other SCSI driver written for a particular HBA. Well, it is really ... hopefully all the hypervisor interfaces won't decide to be completely incompatible, so there's a good chance of code sharing between them. James -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/