From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: [PATCH 5/5] PNP: HP nx6325 fixup: reserve unreported resources Date: Wed, 15 Dec 2010 10:27:50 -0800 Message-ID: <4D0908A6.6010508@zytor.com> References: <20101208213606.13026.47657.stgit@bob.kio> <20101215062650.GB2728@helgaas.com> <201012151118.30512.bjorn.helgaas@hp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <201012151118.30512.bjorn.helgaas@hp.com> Sender: linux-pci-owner@vger.kernel.org To: Bjorn Helgaas Cc: Linus Torvalds , Jesse Barnes , Len Brown , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, "Rafael J. Wysocki" , linux-acpi@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Adam Belay List-Id: linux-acpi@vger.kernel.org On 12/15/2010 10:18 AM, Bjorn Helgaas wrote: > > ACPI devices tend to be at high addresses, so allocating top-down > is definitely more dangerous unless we explicitly avoid them. I > should have realized that and done something like patches 1-3 of > this series before the top-down patches. > > Doing it bottom-up would very likely work better than the "top-down > without avoiding ACPI regions" model we currently have, at least in > the short term. We *would* have to do something to avoid E820 > reservations to fix this: > https://bugzilla.kernel.org/show_bug.cgi?id=16228, > but that's doable. > > So here's my proposal for .37: > - Keep the current state of _CRS enabled by default (for 2008 > and newer machines). > - Allocate bottom-up always > - Avoid E820 reservations > > That should fix all the regressions I'm aware of. I'll work on > the patches this afternoon. > At the same time, I would like to see a few things done as a matter of course: a) reserve the top 2 MiB of the 32-bit address space. There *will* be ROM at the top of the 32-bit address space; it's a fact of the architecture, and on at least older systems it was common to have a shadow 1 MiB below. b) we may want to consider doing special things in the 0xFExxxxxx memory range, which is used by the CPU-APIC-MSI system in recent processors. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.