From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: <3chas3@gmail.com> Received: from mail-io0-f195.google.com (mail-io0-f195.google.com [209.85.223.195]) by dpdk.org (Postfix) with ESMTP id E42CF29C8 for ; Sun, 3 Dec 2017 01:23:42 +0100 (CET) Received: by mail-io0-f195.google.com with SMTP id e204so14997226iof.12 for ; Sat, 02 Dec 2017 16:23:42 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=ewdPDfr1F+z41UfHvDKhVjbrH8orgR6cN+VJSjiU+BA=; b=ApF5RkrsnTSmaTxjUwe3BfhFHwBYPHW05or/xlZI2a2AlKWsnfIVCkIES4aJc5PEOm K9XvrR/yRjTsC7YGT3S/kb9uarrSijxmlLHZEDvmU0leN40tyWeFf9VuLDfaXqncRNlT tT7x59I+C2R7dXV/fDUQE0qoOAyTHlb80fxUDdpRY/8DfvSLk+kvXyKdWaRfbyJ0F5cY LuxMXqDdXK+LetxXFOyA7MTTPLqTOXhXCOWNABkh2HPOzVytup0fQyhzIGVMcRhyHMhf jbJgfbPyRSOIJImy6hqjGIsGI1+S+HRVEHEXPSYk5tcpygvCv3MkLWgEPiWAk+uXJi1F Lddg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=ewdPDfr1F+z41UfHvDKhVjbrH8orgR6cN+VJSjiU+BA=; b=Yg4dPq5oYHJWF8fOzf1LbyLNmYECzzCQNU7mTmonFqrpwxmj6JG0f6fg5Cy/sXldEr MGMnjEh4fPClws/dixfVJ/LWRODLiUeycB59IFDKZRCVMCUA9uKYU2SJCt3Tcrbzrqns 9Xfv39inRJ+gvysjqhB5jhpFXExCnLFzchYoCzqeyL8MAceiL070hXrFBS4pCAFGDteB VkDlW0AMnqGG3uA1ayylhevHLUau1BozfE2AisdxvSO5NX8l+q3PKS3hW07LcNx1NP4w h7z3RUZULdUhlkWw6drUopCIKtXCqNb/TmJ1OSm1Pnm65CsCaCwQ4Kp8CTBprnPHtTsD KHNg== X-Gm-Message-State: AJaThX6YYnNYZQnpbjoGIG5Mzu/2lHUvdc64fXa3JQxaPQVuH1rWf5WB FbrimPmljaqVAdM5R8riJ8l96T2ZmPgwGGFOCUA= X-Google-Smtp-Source: AGs4zMajoXWgmEpNcsuo1Z3ILsc0b6ROaIrwaOtO+QGFiU6vEcMypZcW4XK+6W+61G7ds9+UGNLmtpShJ3wor5pc0D4= X-Received: by 10.107.59.65 with SMTP id i62mr18582744ioa.189.1512260622188; Sat, 02 Dec 2017 16:23:42 -0800 (PST) MIME-Version: 1.0 Received: by 10.107.2.5 with HTTP; Sat, 2 Dec 2017 16:23:41 -0800 (PST) In-Reply-To: <2600590.OO5gESNU7Y@xps> References: <20171130025739.4349-1-3chas3@gmail.com> <2600590.OO5gESNU7Y@xps> From: Chas Williams <3chas3@gmail.com> Date: Sat, 2 Dec 2017 19:23:41 -0500 Message-ID: To: Thomas Monjalon Cc: dev@dpdk.org, anatoly.burakov@intel.com, Chas Williams Content-Type: text/plain; charset="UTF-8" X-Content-Filtered-By: Mailman/MimeDel 2.1.15 Subject: Re: [dpdk-dev] [PATCH] eal: add option to force IOVA as PA mode X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 03 Dec 2017 00:23:43 -0000 The particular machine in my case is a Dell Optiplex 790 which is fairly similar to another system that has basically the same problem. The IOMMU advertises that is can only handle 39 bits of addressing. The DMAR address tables have a width of 36 bits, so all is well when using IOVA physical addresses. With IOVA virtual addresses, they sometimes go beyond the 39 bit boundary. I was under the impression that IOMMU widths are more typically 48 bits, but I appear to have some low end systems with a simpler IOMMU. I could make it a runtime option. On Thu, Nov 30, 2017 at 4:17 AM, Thomas Monjalon wrote: > 30/11/2017 03:57, Chas Williams: > > From: Chas Williams > > > > The IOMMU in some machines report that they can only support > > limited widths. IOVA virtual addresses may exceed this width > > making the use of IOVA virtual addresses difficult. The option > > CONFIG_RTE_LIBRTE_USE_PHYS_IOVA can used to force IOVA physical > > address usage. > > Which machines are you talking about? > A run-time option may be a better solution. > >