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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham 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 E6902C43381 for ; Wed, 20 Feb 2019 09:42:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C382921773 for ; Wed, 20 Feb 2019 09:42:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727087AbfBTJmB (ORCPT ); Wed, 20 Feb 2019 04:42:01 -0500 Received: from mx1.redhat.com ([209.132.183.28]:13002 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726000AbfBTJl7 (ORCPT ); Wed, 20 Feb 2019 04:41:59 -0500 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id EE8F1C058CB0; Wed, 20 Feb 2019 09:41:58 +0000 (UTC) Received: from dhcp-128-65.nay.redhat.com (ovpn-12-36.pek2.redhat.com [10.72.12.36]) by smtp.corp.redhat.com (Postfix) with ESMTPS id AD24A61D1A; Wed, 20 Feb 2019 09:41:50 +0000 (UTC) Date: Wed, 20 Feb 2019 17:41:46 +0800 From: Dave Young To: Borislav Petkov Cc: bhe@redhat.com, Jerry Hoemann , x86@kernel.org, Randy Dunlap , kexec@lists.infradead.org, linux-kernel@vger.kernel.org, Pingfan Liu , Mike Rapoport , Andrew Morton , yinghai@kernel.org, vgoyal@redhat.com, iommu@lists.linux-foundation.org, konrad.wilk@oracle.com, Joerg Roedel Subject: Re: [PATCHv7] x86/kdump: bugfix, make the behavior of crashkernel=X consistent with kaslr Message-ID: <20190220094146.GA8597@dhcp-128-65.nay.redhat.com> References: <20190131105732.GC6749@zn.tnic> <20190131222732.GA946@anatevka> <20190131234740.GO6749@zn.tnic> <20190204223016.GB11986@anatevka> <20190205081552.GG21801@zn.tnic> <20190206120804.GC10062@dhcp-128-65.nay.redhat.com> <20190211204816.GB21473@dhcp-128-65.nay.redhat.com> <20190215102458.GD10433@zn.tnic> <20190218014820.GA10711@dhcp-128-65.nay.redhat.com> <20190220083241.GA3447@zn.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190220083241.GA3447@zn.tnic> User-Agent: Mutt/1.9.5 (2018-04-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Wed, 20 Feb 2019 09:41:59 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/20/19 at 09:32am, Borislav Petkov wrote: > On Mon, Feb 18, 2019 at 09:48:20AM +0800, Dave Young wrote: > > It is ideal if kernel can do it automatically, but I'm not sure if > > kernel can predict the swiotlb reserved size automatically. > > Do you see how even more absurd this gets? > > If the kernel cannot know the swiotlb reserved size automatically, how > is the normal user even supposed to know?! > > I see swiotlb_size_or_default() so we have a sane default which we fall > back to. Now where's the problem with that? Good question, I expect some answer from people who know more about the background. It would be good to have some actual test results, Pingfan is trying to do some tests. Previously Joerg posted below patch, maybe he has some idea. Joerg? commit 94fb9334182284e8e7e4bcb9125c25dc33af19d4 Author: Joerg Roedel Date: Wed Jun 10 17:49:42 2015 +0200 x86/crash: Allocate enough low memory when crashkernel=high Thanks Dave