Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750833Ab2JEGkB (ORCPT ); Fri, 5 Oct 2012 02:40:01 -0400 Received: from nat28.tlf.novell.com ([130.57.49.28]:40306 "EHLO nat28.tlf.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750704Ab2JEGj7 convert rfc822-to-8bit (ORCPT ); Fri, 5 Oct 2012 02:39:59 -0400 Message-Id: <506E9CDC020000780009FD13@nat28.tlf.novell.com> X-Mailer: Novell GroupWise Internet Agent 12.0.0 Date: Fri, 05 Oct 2012 07:39:56 +0100 From: "Jan Beulich" To: "H. Peter Anvin" Cc: , , , , , , Subject: Re: [PATCH 1/3] x86, mm: Include the entire kernel memory map in trampoline_pgd References: <1349269157-25956-1-git-send-email-matt@console-pimps.org> <1349269157-25956-2-git-send-email-matt@console-pimps.org> <506C4C3A020000780008D041@nat28.tlf.novell.com> <506DFAD8.5060701@zytor.com> In-Reply-To: <506DFAD8.5060701@zytor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1415 Lines: 39 >>> On 04.10.12 at 23:08, "H. Peter Anvin" wrote: > On 10/03/2012 06:31 AM, Jan Beulich wrote: >>>>> Matt Fleming 10/03/12 2:59 PM >>> >>> +static int insert_identity_mapping(resource_size_t paddr, unsigned long > vaddr, >>> + unsigned long size) >>> +{ >>> + unsigned long end = vaddr + size; >>> + unsigned long next; >>> + pgd_t *vpgd, *ppgd; >>> + >>> +#ifdef CONFIG_X86_32 >>> + ppgd = initial_page_table + pgd_index(paddr); >>> + >>> + if (paddr >= PAGE_OFFSET || paddr + size > PAGE_OFFSET) >>> + return 1; >>> +#else >>> + ppgd = __va(real_mode_header->trampoline_pgd) + pgd_index(paddr); >> >> Missing equivalent code (to the 32-bit one above) here - after all, you're > trying >> to potentially insert a 52-bit physical address into 48-bit virtual space. >> > > We should have the check, but at least for Linux support we require > P <= V-2. Not really imo - P <= V - 1 should be sufficient here, as all that is necessary is that the result represents a 1:1 mapping. Specifically, there's no constraint to the virtual space limitation of the direct mapping of RAM. Jan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/