From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030469AbcBQRHY (ORCPT ); Wed, 17 Feb 2016 12:07:24 -0500 Received: from g4t3425.houston.hp.com ([15.201.208.53]:43220 "EHLO g4t3425.houston.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965115AbcBQRHX (ORCPT ); Wed, 17 Feb 2016 12:07:23 -0500 Message-ID: <1455732020.2925.255.camel@hpe.com> Subject: Re: [PATCH 3/3] ACPI: Change NFIT driver to set PMEM type to iomem entry From: Toshi Kani To: Dan Williams Cc: "linux-nvdimm@lists.01.org" , "Rafael J. Wysocki" , "linux-kernel@vger.kernel.org" , Linux ACPI , Andrew Morton , Borislav Petkov , Ingo Molnar Date: Wed, 17 Feb 2016 11:00:20 -0700 In-Reply-To: <1455674441.2925.204.camel@hpe.com> References: <1454439311-23690-1-git-send-email-toshi.kani@hpe.com> <1454439311-23690-4-git-send-email-toshi.kani@hpe.com> <1455316203.2925.132.camel@hpe.com> <1455674441.2925.204.camel@hpe.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.18.4 (3.18.4-1.fc23) Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2016-02-16 at 19:00 -0700, Toshi Kani wrote: > On Fri, 2016-02-12 at 15:32 -0800, Dan Williams wrote: > > On Fri, Feb 12, 2016 at 2:30 PM, Toshi Kani wrote: > > > On Fri, 2016-02-12 at 11:41 -0800, Dan Williams wrote: > > > > On Tue, Feb 2, 2016 at 10:55 AM, Toshi Kani > > > > wro >  : > > > > Hmm, if we set the type on driver load, should we clear the type on > > > > driver unload? > > > > > > I think this type update should stay for the life-cycle of this iomem > > > entry itself since this range is PMEM even after the driver is > > > unloaded.  This is an extension of the boot-time iomem table > > > initialization from e820/EFI, which allows ACPI to set a correct > > > type.  This is independent from driver's resource allocations. > > > > > > > Actually it might be more straightforward to specify a type at > > > > request_region() time.  That way it gets released at > > > > release_region().  We're already setting a resource name at > > > > request_region time, adding a type annotation at the time seems > > > > appropriate. > > > > > > I first considered simply setting "namespaceX.X" as PMEM.  However, > > > region_intersects() and its friends only check the top-level entries, > > > not their children, of the iomem table.  And I think a child should > > > have the same type as the parent as I fixed it in patch 1/3. > > > > Did we investigate updating region_intersects() to check children? > > When a child sub-divides a region with different types it may be the > > wrong answer to check the parent.  Is there a problem with moving > > checking to the child? > > Here are three options I can think of. > > 1) Set pmem type to "reserved" (This patch-set) >  - Add a new iomem_set_desc(), which sets a given type to a top-level > entry.  Change the ACPI NFIT driver to call it to set pmem type to > "reserved" entry. >  - region_intersects() finds a pmem entry by checking top-level entries > (no change). > > 2) Change region_intersects() to check children's type >  - Add a new request_region_ext(), which is an extension to > request_region() to allow specifying a type of resource.  It puts a new > child entry under "reserved".  Change the pmem driver to call this func. >  - Change region_intersects() to check children's type for finding this > child pmem entry. > > 3) Pmem driver to call insert_resource() >  - Change the pmem driver to call insert_resource(), which puts a new > pmem entry as the parent of "reserved". >  - region_intersects() finds a pmem entry by checking top-level entries > (no change). >  - Add a new release_resource_self(), which releases a given entry and > keeps its children if any.  Change the pmem driver to call it for > release. Thinking further, 3) needs to be modified as follows.  insert_resource() should only be allowed for producers of resource (ex. nfit), not consumers (ex. pmem).  It also needs to export insert_resource(). 3) NFIT driver to call insert_resource()  - Change the ACPI nfit driver to call insert_resource() when a target range is not marked as PMEM (i.e. "reserved") or not present in iomem.  This puts a new PMEM entry as the parent of "reserved".  - region_intersects() finds a pmem entry by checking top-level entries (no change).  - Add a new release_resource_self(), which releases a given entry and keeps its children if any.  Change the nfit driver to call it for release. > This patch-set implements 1).  The pmem type is set to "reserved" for its > life-cycle.  This option is simplest. > > For 2), the changes to region_intersects() may be too complex for > maintenance.   I should have said "region_intersects() may be overly complicated for this purpose and maintenance". > Here are a few examples when region_intersects() is called > with addr [1-10] where iomem has entry P and its children. > > Case A: P is fully covered by children C1 & C2.  region_intersects() > ignores P's type, but checks C1 and C2's. >    >   P [1-10] + C1 [1-5] >            + C2 [6-10] > > Case B: C2 is fully covered by C3, but P is not.  region_intersects() > ignores C2's type, but checks P, C1, C3's. > >   P [1-10] + C1 [1-2] >            + C2 [6-10] + C3 [6-10] > > I think region_intersects() will need to construct a flat table from the > tree while making recursive calls to walk thru all children. > > 3) is similar to 2), but avoids the changes to region_intersects() since > insert_resource() inserts a new entry as the parent to "reserved". 3) is actually similar to 1) as both options change the producer side. >  However, a new interface is necessary to put "reserved" back to top- > level when releasing the added entry. > > My recommendation is go with either 1) or 3).  What do you think? I think we should modify the producer side, so 1) or 3) are still my recommendation. Thanks, -Toshi