From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758564Ab2EaXDK (ORCPT ); Thu, 31 May 2012 19:03:10 -0400 Received: from terminus.zytor.com ([198.137.202.10]:59077 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758244Ab2EaXDJ (ORCPT ); Thu, 31 May 2012 19:03:09 -0400 References: <1338493218-25006-1-git-send-email-konrad.wilk@oracle.com> <4FC7D2AE.9080603@zytor.com> <20120531203544.GA19420@phenom.dumpdata.com> User-Agent: K-9 Mail for Android In-Reply-To: <20120531203544.GA19420@phenom.dumpdata.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Subject: Re: [PATCH] x86/i386: Check PSE bit before using PAGE_KERNEL_LARGE. From: "H. Peter Anvin" Date: Thu, 31 May 2012 16:02:11 -0700 To: Konrad Rzeszutek Wilk CC: konrad@darnok.org, linux-kernel@vger.kernel.org, x86@kernel.org, mingo@redhat.com, tglx@linutronix.de, stable@kernel.org Message-ID: <91130b9a-1324-4435-b642-427c2aa23121@email.android.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org No, PAE kernels cannot boot on non-PAE hardware. Konrad Rzeszutek Wilk wrote: >On Thu, May 31, 2012 at 01:21:02PM -0700, H. Peter Anvin wrote: >> On 05/31/2012 12:40 PM, Konrad Rzeszutek Wilk wrote: >> > During bootup we would unconditionally do this on any >> > machine that was built with CONFIG_NUMA=y on i386: >> > >> > setup_arch >> > \-initmem_init >> > \-x86_numa_init (with dummy_init as callback) >> > \- init_alloc_remap >> > \- set_pmd_pfn (with PAGE_PSE) >> > >> > without checking to see if the CPU supports PSE. This >> > patch adds that and also allows the init_alloc_remap function >> > to properly work by falling back on PTEs. >> > >> >> Well, the code looks like it is PAE-specific, and PAE implies PSE. > >I have to double check - but I think a kernel built with >CONFIG_HIGHMEM64=y >and CONFIG_NUMA=y would boot on a Pentium II which can't do PAE. > >But perhaps there are some other checks that would halt the kernel >before it even got there? > >> >> Xen breaks that, but that is a divergence of Xen from x86. > >It certainly does . And that is how I spotted this - b/c the >PMD would fail (with tons of mutlicalls warnings) - and the PTE's >would still point to the old PFNs. -- Sent from my mobile phone. Please excuse brevity and lack of formatting.