From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [Linux-nvdimm] another pmem variant Date: Wed, 25 Mar 2015 17:44:28 +0100 Message-ID: <20150325164428.GA1099@lst.de> References: <1427299449-26722-1-git-send-email-hch@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Christoph Hellwig , linux-nvdimm , linux-fsdevel , "linux-kernel@vger.kernel.org" , X86 ML , Jens Axboe To: Dan Williams Return-path: Received: from verein.lst.de ([213.95.11.211]:48675 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932091AbbCYQoa (ORCPT ); Wed, 25 Mar 2015 12:44:30 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Wed, Mar 25, 2015 at 09:33:52AM -0700, Dan Williams wrote: > This is mostly ok and does not collide too much with the upcoming ACPI > mechanism for this stuff. I do worry that the new > "memmap=nn[KMG]!ss[KMG]" kernel command line option will only be > relevant for at most one kernel cycle given the imminent publication > of the spec that unblocks our release. I don't think we can just get rid of it as legacy systems won't be upgraded to the new discovery mechanism. Or do you mean you plan to introduce a better override on the command line? In that case speak up now! > Our planned solution to the "legacy pmem" problem is to have a > userspace utility craft a list of address ranges in the form that ACPI > expects and attach that to a platform device (one time setup). It > only requires that the memory be marked reserved, not necessarily > marked type-12. I can't see any benefit of that over just doign the right thing in kernel space. > > The other two patches are a heavily rewritten version of the code that > > Intel gave to various storage vendors to discover the type 12 (and earlier > > type 6) nvdimms, which I massaged into a form that is hopefully suitable > > for mainline. > > I'd prefer E820_PMEM over E820_PROTECTED_KERN, I don't know why I > chose that name initially, but to each his own bike shed. Sounds fine to me.