Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756458AbZICV1p (ORCPT ); Thu, 3 Sep 2009 17:27:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756417AbZICV1p (ORCPT ); Thu, 3 Sep 2009 17:27:45 -0400 Received: from mail-yw0-f192.google.com ([209.85.211.192]:56236 "EHLO mail-yw0-f192.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756380AbZICV1o (ORCPT ); Thu, 3 Sep 2009 17:27:44 -0400 X-Greylist: delayed 381 seconds by postgrey-1.27 at vger.kernel.org; Thu, 03 Sep 2009 17:27:43 EDT DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; b=lKFmElDzlbLXrasqEiHY1ey0/xIrhLgX5EJjCukLiRc7iafyg9P70MLzRBTmIRgoWn gkPxCsO4g5QooN6FA+cMNcCGUX4x+JM1MDxeK56jW5fuPtqG4mM7JvwR895uqysvZcfE 47WlQQG5p0W7sfee/qYFG8QHHFRyJNm69hBi8= Message-ID: <4AA03370.4080905@gmail.com> Date: Thu, 03 Sep 2009 17:21:52 -0400 From: Ric Wheeler User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.1) Gecko/20090814 Fedora/3.0-2.6.b3.fc11 Lightning/1.0pre Thunderbird/3.0b3 MIME-Version: 1.0 To: Dmitry Torokhov CC: James Bottomley , Alok Kataria , Matthew Wilcox , Roland Dreier , Bart Van Assche , Robert Love , Randy Dunlap , Mike Christie , "linux-scsi@vger.kernel.org" , LKML , Andrew Morton , Rolf Eike Beer , Maxime Austruy Subject: Re: [PATCH] SCSI driver for VMware's virtual HBA. References: <1251415060.16297.58.camel@ank32.eng.vmware.com> <1251911789.23106.25.camel@ank32.eng.vmware.com> <1252008182.3941.61.camel@mulgrave.site> <200909031331.03037.dtor@vmware.com> In-Reply-To: <200909031331.03037.dtor@vmware.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2094 Lines: 43 On 09/03/2009 04:31 PM, Dmitry Torokhov wrote: > On Thursday 03 September 2009 01:03:02 pm James Bottomley wrote: > >>>> I'm not really asking you to standardise anything (yet). I was more >>>> probing for why you hadn't included any of the SCSI control plane >>>> interfaces and what lead you do produce a different design from the >>>> current patterns in virtual I/O. I think what I'm hearing is "Because >>>> we didn't look at how modern SCSI drivers are constructed" and "Because >>>> we didn't look at how virtual I/O is currently done in Linux". That's >>>> OK (it's depressingly familiar in drivers), >>>> >>> I am sorry that's not the case, the reason we have different design as I >>> have mentioned above is because we want a generic mechanism which works >>> for all/most of the GOS's out their and doesn't need to be specific to >>> Linux. >>> >> Slightly confused now ... you're saying you did look at the transport >> class and virtio? But you chose not to do a virtio like interface (for >> reasons which I'm still not clear on) ... >> > Virtio is Linux-specific and is not available on older kernels which > our hypervisor/PVSCSI combination does support. Even if we were to use > virtio-like schema in the hypervisor code we would have to re-implement > much of the virtio code for kernels earlier than those shipped in '07 > and do the same for other operating systems for no apparent benefit. > The PCI device abstraction is self-contained and works well on Windows, > Linux and other guest operating systems and so it was chosen. > > Several arguments have a history of never winning when you try to get a new bit of code in linux. Number one in the bad justifications is that your design is good because it avoids being "linux specific" closely followed by needing to backport :-) ric -- 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/