Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751535AbbKJUxT (ORCPT ); Tue, 10 Nov 2015 15:53:19 -0500 Received: from g2t4625.austin.hp.com ([15.73.212.76]:36024 "EHLO g2t4625.austin.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750749AbbKJUxR (ORCPT ); Tue, 10 Nov 2015 15:53:17 -0500 Message-ID: <56425939.7000605@hpe.com> Date: Tue, 10 Nov 2015 15:53:13 -0500 From: Linda Knippers User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Dan Williams , Jerry Hoemann CC: linux-nvdimm , "Rafael J. Wysocki" , "linux-kernel@vger.kernel.org" , Linux ACPI , Len Brown Subject: Re: [PATCH 1/4] nvdimm: Add wrapper for IOCTL pass thru. References: <5411049831df211c8280e3239aaf344af033fa25.1446684001.git.jerry.hoemann@hpe.com> <20151110194938.GA47666@tevye.fc.hp.com> In-Reply-To: Content-Type: text/plain; charset=windows-1252; 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: 2299 Lines: 53 On 11/10/2015 3:27 PM, Dan Williams wrote: > On Tue, Nov 10, 2015 at 11:49 AM, Jerry Hoemann wrote: >> On Tue, Nov 10, 2015 at 12:51:59PM -0500, Jeff Moyer wrote: >>> Jerry Hoemann writes: >>> >>>> Add IOCTL type 'P' to denote NVDIMM_TYPE_PASSTHRU. >>> >>> Can't you just make passthrough a separate command? If you actually add >> >> There are multiple conflicting NVDIMM _DSM running around, they >> are "device specific". So, we should plan in general and not just >> for the example DSM that Intel added support for. These DSM have >> over lapping and incompatible function ids. >> >> The Intel example is an example, not standard. They are free to >> change it at will. So, we can't be certain there won't be a >> conflict some time in the future if we try to use their number space. >> >> I'm trying to create a generic pass thru that any vendors can use. Putting >> this in the Intel function number space doesn't make a lot of sense to me. > > It isn't the "Intel" function number space. The fact that they > currently align is just a happy accident. It's not really a happy accident. Your commit message says it was derived from the Intel spec 'for convenience', which I think is convenient for anything that implements that spec. We've discussed ways of supporting different command sets with you and determined that this pass-through mechanism was a good approach because it allows multiple different command sets to be support in a generic way. Blending the two flavors (generic pass through and explicit function definitions) is confusing to me. > The kernel is free to break > the 1:1 ioctl number to DSM function number relationship, and I think > it would make the implementation cleaner in this case. To me it's less clean and even for your own example spec, less convenient if Intel ever updates that spec. -- ljk > _______________________________________________ > Linux-nvdimm mailing list > Linux-nvdimm@lists.01.org > https://lists.01.org/mailman/listinfo/linux-nvdimm > -- 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/