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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FAKE_REPLY_C,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 D112CC432C0 for ; Fri, 29 Nov 2019 14:58:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 946D1217BA for ; Fri, 29 Nov 2019 14:58:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1575039532; bh=sXa4biqXFrdIASdos+I8wNXn3kPutmv7T3yShrfLJYc=; h=Date:From:To:Cc:Subject:In-Reply-To:List-ID:From; b=QRGYXB758xgbcFQiL7H0Be7agFqUtSs7X6mS4120r3/LUz+Y2n2/C3Akt+LZII4fx LoqfzOBdOp1fw0eZsb67+lq4cQbZSRliKYrgzQAYCjfnY0N9N4+7HlT0t6k0q65EsT 7vnbG5hm/Tp6ZgyNtyrpiP0k4k0OQbrLqMncq2x4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726903AbfK2O6w (ORCPT ); Fri, 29 Nov 2019 09:58:52 -0500 Received: from mail.kernel.org ([198.145.29.99]:33518 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726843AbfK2O6w (ORCPT ); Fri, 29 Nov 2019 09:58:52 -0500 Received: from localhost (173-25-83-245.client.mchsi.com [173.25.83.245]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 48F572070B; Fri, 29 Nov 2019 14:58:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1575039531; bh=sXa4biqXFrdIASdos+I8wNXn3kPutmv7T3yShrfLJYc=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=ePCl2vGvwf25XknBMUXShUiD5Dm4gh3ukeu0fzByCh5QCk/bltf7zbb8Y+Kdq9OAV eo6vGyjzZYCm0U+IqCYpqz2xzBLm+69qzeilJwbmFzvclzsbO9HQdqj+MWW0lzBgp7 rRFyv8u0ARhObnGiEDlkaH5i8p67GSUaklhu2EPI= Date: Fri, 29 Nov 2019 08:58:49 -0600 From: Bjorn Helgaas To: ranshalit@gmail.com Cc: bjorn@helgaas.com, linux-pci@vger.kernel.org Subject: Re: [Bug 205701] New: Can't access RAM from PCIe Message-ID: <20191129145849.GA203450@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Fri, Nov 29, 2019 at 06:59:48AM +0000, bugzilla-daemon@bugzilla.kernel.org wrote: > https://bugzilla.kernel.org/show_bug.cgi?id=205701 > ... > > Using Intel Xeon computer with linux kernel 4.18.0 centos8. > Trying to access RAM (with DMA) using FPGA fails in this computer. > > 1. I tried to add intel_iommu=off - it did not help. > > 2. Installing windows on same PC - FPGA can access RAM using DMA without > issues. > > 3. using another PC (Intel Duo) with same linux and OS - FPGA access works. > > FPGA access the RAM using a physical address provided by a kernel module which > allocates physical continuous memory in PC. (the module works perfectly with > Intel Duo on exactly same OS and kernel). Hi, thanks for the report! Can you please attach the complete dmesg and "sudo lspci -vv" output for the working and non-working v4.18 kernels to the bugzilla? Then please try to reproduce the problem on the current v5.4 kernel and attach the v5.4 dmesg log. If v5.4 fails, we'll have to debug it. If v5.4 works, figure out what fixed it (by comparing dmesg logs or by bisection) and backport it to v4.18. Bjorn