Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751907AbbEAQXq (ORCPT ); Fri, 1 May 2015 12:23:46 -0400 Received: from mail-wi0-f177.google.com ([209.85.212.177]:35369 "EHLO mail-wi0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751568AbbEAQXk (ORCPT ); Fri, 1 May 2015 12:23:40 -0400 MIME-Version: 1.0 In-Reply-To: <2235175.7DaGPJD1E4@vostro.rjw.lan> References: <20150428181203.35812.60474.stgit@dwillia2-desk3.amr.corp.intel.com> <5532780.fyo4CQJEJz@vostro.rjw.lan> <2235175.7DaGPJD1E4@vostro.rjw.lan> Date: Fri, 1 May 2015 09:23:38 -0700 Message-ID: Subject: Re: [PATCH v2 02/20] libnd, nd_acpi: initial libnd infrastructure and NFIT support From: Dan Williams To: "Rafael J. Wysocki" Cc: "linux-nvdimm@lists.01.org" , Linux ACPI , "Rafael J. Wysocki" , Robert Moore , "linux-kernel@vger.kernel.org" , David Box Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5137 Lines: 133 On Thu, Apr 30, 2015 at 6:21 PM, Rafael J. Wysocki wrote: > On Thursday, April 30, 2015 05:39:06 PM Dan Williams wrote: >> On Thu, Apr 30, 2015 at 4:23 PM, Rafael J. Wysocki wrote: [..] >> >> +if ND_DEVICES >> >> + >> >> +config LIBND >> >> + tristate "LIBND: libnd device driver support" >> >> + help >> >> + Platform agnostic device model for a libnd bus. Publishes >> >> + resources for a PMEM (persistent-memory) driver and/or BLK >> >> + (sliding mmio window(s)) driver to attach. Exposes a device >> >> + topology under a "ndX" bus device, a "/dev/ndctlX" bus-ioctl >> >> + message passing interface, and a "/dev/nmemX" dimm-ioctl >> >> + message interface for each memory device registered on the >> >> + bus. instance. A userspace library "ndctl" provides an API >> >> + to enumerate/manage this subsystem. >> >> + >> >> +config ND_ACPI >> >> + tristate "ACPI: NFIT to libnd bus support" >> >> + select LIBND >> >> + depends on ACPI >> >> + help >> >> + Infrastructure to probe ACPI 6 compliant platforms for >> >> + NVDIMMs (NFIT) and register a libnd device tree. In >> >> + addition to storage devices this also enables libnd craft >> >> + ACPI._DSM messages for platform/dimm configuration. >> > >> > I'm wondering if the two CONFIG options above really need to be user-selectable? >> > >> > For example, what reason people (who've already selected ND_DEVICES) may have >> > for not selecting ND_ACPI if ACPI is set? >> >> >> Later on in the series we introduce ND_E820 which supports creating a >> libnd-bus from e820-type-12 memory ranges on pre-NFIT systems. I'm >> also considering a configfs defined libnd-bus because e820 types are >> not nearly enough information to safely define nvdimm resources >> outside of NFIT. > > I hope these are not mutually exclusive with ND_ACPI? Otherwise distros > will have problems with supporting them in one kernel. You can have ND_E820 support and ND_ACPI support in the same system. Likely an NFIT enabled system will never have e820-type-12 ranges, but if a user messes up and uses the new memmap=ss!nn command line to overlap NFIT-defined memory then the request_mem_region() calls in the driver will collide. First to load wins in that scenario. > If ND_E820 and ND_ACPI aren't mutually exclusive, I still don't see a good > enough reason for asking users about ND_ACPI. Why would I ever say "No" > here if I said "Yes" or "Module" to ND_DEVICES? I agree that if the user selects ND_DEVICES then ND_ACPI should probably default on, but otherwise turning it off is a useful option. If you know your system is pre-ACPI-6 then why bother including support? >> >> + >> >> +endif >> >> diff --git a/drivers/block/nd/Makefile b/drivers/block/nd/Makefile >> >> new file mode 100644 >> >> index 000000000000..944b5947c0cb >> >> --- /dev/null >> >> +++ b/drivers/block/nd/Makefile >> >> @@ -0,0 +1,6 @@ >> >> +obj-$(CONFIG_LIBND) += libnd.o >> >> +obj-$(CONFIG_ND_ACPI) += nd_acpi.o >> >> + >> >> +nd_acpi-y := acpi.o >> >> + >> >> +libnd-y := core.o >> > >> > OK, so it looks like no modules, just built-in code, right? >> > >> >> Um, no, both CONFIG_ND_ACPI and CONFIG_LIBND can be =m. > > OK > > [cut] > >> >> +static int nd_acpi_remove(struct acpi_device *adev) >> >> +{ >> >> + struct acpi_nfit_desc *acpi_desc = dev_get_drvdata(&adev->dev); >> >> + >> >> + nd_bus_unregister(acpi_desc->nd_bus); >> >> + return 0; >> >> +} >> >> + >> >> +static void nd_acpi_notify(struct acpi_device *adev, u32 event) >> >> +{ >> >> + /* TODO: handle ACPI_NOTIFY_BUS_CHECK notification */ >> >> + dev_dbg(&adev->dev, "%s: event: %d\n", __func__, event); >> >> +} >> >> + >> >> +static const struct acpi_device_id nd_acpi_ids[] = { >> >> + { "ACPI0012", 0 }, >> >> + { "", 0 }, >> >> +}; >> >> +MODULE_DEVICE_TABLE(acpi, nd_acpi_ids); >> >> + >> >> +static struct acpi_driver nd_acpi_driver = { >> >> + .name = KBUILD_MODNAME, >> >> + .ids = nd_acpi_ids, >> >> + .flags = ACPI_DRIVER_ALL_NOTIFY_EVENTS, >> >> + .ops = { >> >> + .add = nd_acpi_add, >> >> + .remove = nd_acpi_remove, >> >> + .notify = nd_acpi_notify >> >> + }, >> >> +}; >> > >> > Since this is going to be non-modular built-in code, please use an ACPI >> > scan handler instead of using a driver here. acpi_memhotplug.c does that, >> > you can use it as an example, but I guess you don't need to enable hotplug >> > for it to start with. >> >> >> No, you misunderstood, this will certainly be modular and loaded on-demand. > > OK > > So please drop the .notify thing at least for now. It most likely doesn't do > what you need anyway. The .notify handler will eventually be filled in to handle hot-add of NFIT structures, but yes I'll drop it for now. -- 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/