Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752059AbdGAUIy (ORCPT ); Sat, 1 Jul 2017 16:08:54 -0400 Received: from mail-yb0-f180.google.com ([209.85.213.180]:35656 "EHLO mail-yb0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751940AbdGAUIw (ORCPT ); Sat, 1 Jul 2017 16:08:52 -0400 MIME-Version: 1.0 In-Reply-To: <20170701195805.GA13259@anatevka.americas.hpqcorp.net> References: <293ee143dcabb386ca06b384a384171c256a2ecc.1498810220.git.jerry.hoemann@hpe.com> <20170701195805.GA13259@anatevka.americas.hpqcorp.net> From: Dan Williams Date: Sat, 1 Jul 2017 13:08:50 -0700 Message-ID: Subject: Re: [PATCH v4 3/6] libnvdimm, acpi, nfit: Add bus level dsm mask for pass thru. To: Jerry Hoemann Cc: "linux-nvdimm@lists.01.org" , "linux-kernel@vger.kernel.org" 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: 2661 Lines: 58 On Sat, Jul 1, 2017 at 12:58 PM, Jerry Hoemann wrote: > On Fri, Jun 30, 2017 at 08:55:22PM -0700, Dan Williams wrote: > > ... > >> On Fri, Jun 30, 2017 at 9:09 AM, Jerry Hoemann wrote: >> > + if (cmd == ND_CMD_CALL) >> > + dsm_mask = nd_desc->bus_dsm_mask; >> > desc = nd_cmd_bus_desc(cmd); >> > uuid = to_nfit_uuid(NFIT_DEV_BUS); >> > handle = adev->handle; >> > @@ -1613,6 +1615,7 @@ static void acpi_nfit_init_dsms(struct acpi_nfit_desc *acpi_desc) >> > struct nvdimm_bus_descriptor *nd_desc = &acpi_desc->nd_desc; >> > const u8 *uuid = to_nfit_uuid(NFIT_DEV_BUS); >> > struct acpi_device *adev; >> > + unsigned long dsm_mask; >> > int i; >> > >> > nd_desc->cmd_mask = acpi_desc->bus_cmd_force_en; >> > @@ -1624,6 +1627,11 @@ static void acpi_nfit_init_dsms(struct acpi_nfit_desc *acpi_desc) >> > if (acpi_check_dsm(adev->handle, uuid, 1, 1ULL << i)) >> > set_bit(i, &nd_desc->cmd_mask); >> > set_bit(ND_CMD_CALL, &nd_desc->cmd_mask); >> > + >> > + dsm_mask = 0x3bf; >> >> I went ahead and fixed this up to use dsm_mask defined like this: >> >> + dsm_mask = >> + (1 << ND_CMD_ARS_CAP) | >> + (1 << ND_CMD_ARS_START) | >> + (1 << ND_CMD_ARS_STATUS) | >> + (1 << ND_CMD_CLEAR_ERROR) | >> + (1 << NFIT_CMD_TRANSLATE_SPA) | >> + (1 << NFIT_CMD_ARS_INJECT_SET) | >> + (1 << NFIT_CMD_ARS_INJECT_CLEAR) | >> + (1 << NFIT_CMD_ARS_INJECT_GET); >> >> This drops function number 0 which userspace has no need to call. > > Actually I like to call function 0. Its an excellent test when > modifying the code path as its a no side effects function whose output > is known in advance and instantly recognizable. I also use it when > testing new firmware. > > What is the downside to allowing it? What bad things happen? It allows implementations to bypass the standardization process and ship new root DSMs. It's always possible to patch the kernel locally for development, so I see no reason to ship this capability globally. > Also, I do have to ask why you allow function zero for NVDIMM_FAMILY_MSFT? Yeah, that's an oversight / mistake, but it's also benign since it can't be used to add support for new function numbers to the family since all 32 numbers are already taken. We also allow override for leaf devices since there's quite a bit more per vendor differentiation that might take a while to standardize.