From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E61C9C10F00 for ; Fri, 6 Mar 2020 21:05:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BA66C20717 for ; Fri, 6 Mar 2020 21:05:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=intel-com.20150623.gappssmtp.com header.i=@intel-com.20150623.gappssmtp.com header.b="zHeO+NAS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726462AbgCFVFm (ORCPT ); Fri, 6 Mar 2020 16:05:42 -0500 Received: from mail-ot1-f67.google.com ([209.85.210.67]:44328 "EHLO mail-ot1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726231AbgCFVFm (ORCPT ); Fri, 6 Mar 2020 16:05:42 -0500 Received: by mail-ot1-f67.google.com with SMTP id v22so3805061otq.11 for ; Fri, 06 Mar 2020 13:05:42 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=a1kF/OZzMQLactEcP2uvKaRdr9m2gxg0zsQwgDcUpS8=; b=zHeO+NASipBgaWDXKZxHQ9T6Qk7JyQTufn1LqoKL9eCvWxA6ERYUyq5brfvaGK2Q2T O/1XtzLEJ1OB063KrHNDlljqirAy6dSyKF1iCoBOl1Vku6umli7wybNDN4liHG6HiEkL iJQBdSeZVh2iwysFc31yvgGzAfDguHevXnkROYvBITGUqkec3Q6DiV6vn3qAjCSwkC6V 7yLNzobtVea45nRJ6F+O3pxCAX7i2s3r6qp0ctkisp7YTbLrPNxHKjQpvGQULi0khAfv gHd+Vg6XcX50oieboKdVEQSwY9XXXxKOGwnkGWC6OtC68at4+VqDSlJ0yEpTWQIPL97W CziA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=a1kF/OZzMQLactEcP2uvKaRdr9m2gxg0zsQwgDcUpS8=; b=s3+kOdNEfMOS5hG3oUxyNhMHoqvbEI8B2RJ4ciulAo+U7yRctc7Z2mTAaxyBSfVugB uZ5xYxdoChdR2QUdSvbjyu6bS24g1MrotLUF8ajMDYVb77CNUuA7VRQci69WXNEGEjUw K+gdtHRmj41x25gGpR2VSU+Op2nKDpWTcZ5Var31SzzMMZxomSLbs8zWcqY/eafYvDKT FeTNFxJCg9t6ljzCXCu0RqBP5uHC8kQxlPmyMn+HHhDIvvvJIKOjVv193bmpsxY8QfuT qFuzlHTqWe6hXHLXzw7dgmtLquxh6In6vCiVF3UZf2wFxvVZEjMC5M/HcBlxYPj0IAya yoDg== X-Gm-Message-State: ANhLgQ0Z4D1ZD0aFXs1f1X9HlUo+Cw9KCy3He/6OpYVvYmyk40rJ4Tpt KD/yuHy3wdNsSbOsBxBxCYuLKvqr706snsKertzV+Q== X-Google-Smtp-Source: ADFU+vu3caJkxN5foYyF0GPM62BSitG6fiBBhbRTadus2AVityefuk0oEkE1SzZK3vy+IUU4Bmf/G7dorCK3e8I7x8s= X-Received: by 2002:a05:6830:1313:: with SMTP id p19mr763057otq.126.1583528741694; Fri, 06 Mar 2020 13:05:41 -0800 (PST) MIME-Version: 1.0 References: <158318759687.2216124.4684754859068906007.stgit@dwillia2-desk3.amr.corp.intel.com> In-Reply-To: From: Dan Williams Date: Fri, 6 Mar 2020 13:05:30 -0800 Message-ID: Subject: Re: [PATCH 0/5] Manual definition of Soft Reserved memory devices To: Jeff Moyer Cc: Linux ACPI , Jason Gunthorpe , Peter Zijlstra , Ard Biesheuvel , Jonathan Cameron , Borislav Petkov , Wei Yang , X86 ML , "H. Peter Anvin" , Brice Goglin , Thomas Gleixner , Ingo Molnar , Dave Hansen , "Rafael J. Wysocki" , Ard Biesheuvel , Andy Lutomirski , Tom Lendacky , linux-nvdimm , Linux Kernel Mailing List , Joao Martins Content-Type: text/plain; charset="UTF-8" Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On Fri, Mar 6, 2020 at 12:07 PM Jeff Moyer wrote: > > Dan Williams writes: > > > Given the current dearth of systems that supply an ACPI HMAT table, and > > the utility of being able to manually define device-dax "hmem" instances > > via the efi_fake_mem= option, relax the requirements for creating these > > devices. Specifically, add an option (numa=nohmat) to optionally disable > > consideration of the HMAT and update efi_fake_mem= to behave like > > memmap=nn!ss in terms of delimiting device boundaries. > > So, am I correct in deducing that your primary motivation is testing > without hardware/firmware support? My primary motivation is making the dax_kmem facility useful to shipping platforms that have performance differentiated memory, but may not have EFI-defined soft-reservations / HMAT (or non-EFI-ACPI-platform equivalent). I'm anticipating HMAT enabled platforms where the platform firmware policy for what is soft-reserved, or not, is not the policy the system owner would pick. I'd also highlight Joao's work [1] (see the TODO section) as an indication of the demand for custom carving memory resources and applying the device-dax memory management interface. > This looks like a bit of a hack to > me, and I think maybe it would be better to just emulate the HMAT using > qemu. I don't have a strong objection, though. Yeah, qemu emulation does not help when you, the system owner, have a different use case than what the bare-metal platform-firmware envisioned for "specific-purpose memory". [1]: https://lore.kernel.org/lkml/20200110190313.17144-1-joao.m.martins@oracle.com/