Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759572Ab1FWPPd (ORCPT ); Thu, 23 Jun 2011 11:15:33 -0400 Received: from smtp.eu.citrix.com ([62.200.22.115]:39116 "EHLO SMTP.EU.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758839Ab1FWPPc (ORCPT ); Thu, 23 Jun 2011 11:15:32 -0400 X-IronPort-AV: E=Sophos;i="4.65,413,1304294400"; d="scan'208";a="6450958" Date: Thu, 23 Jun 2011 16:19:32 +0100 From: Stefano Stabellini X-X-Sender: sstabellini@kaball-desktop To: =?UTF-8?Q?Penttil=C3=A4_Mika?= CC: Stefano Stabellini , "linux-kernel@vger.kernel.org" Subject: RE: [PATCH] x86_64: do not assume head_64.S used 4KB pages when !use_pse In-Reply-To: <1A61D8EA6755AF458F06EA669A4EC8182F05B0C6@JKLMAIL02.ixonos.local> Message-ID: References: <1A61D8EA6755AF458F06EA669A4EC8182F05B07E@JKLMAIL02.ixonos.local> <1A61D8EA6755AF458F06EA669A4EC8182F05B0C6@JKLMAIL02.ixonos.local> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="8323329-559770896-1308841709=:12963" Content-ID: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1907 Lines: 52 --8323329-559770896-1308841709=:12963 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Content-ID: On Thu, 23 Jun 2011, Penttilä Mika wrote: > > > And arch/x86/mm/init.c also has: > > > > > > #if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KMEMCHECK) > > > /* > > > * For CONFIG_DEBUG_PAGEALLOC, identity mapping will use > > small pages. > > > * This will simplify cpa(), which otherwise needs to support > > splitting > > > * large pages into small in interrupt context, etc. > > > */ > > > use_pse = use_gbpages = 0; > > > #else > > > use_pse = cpu_has_pse; > > > use_gbpages = direct_gbpages; > > > #endif > > > > > > > > > So big pages are also not used for DEBUG_PAGEALLOC and KMEMCHECK > > configs even if head_32.S did. > > > > Right, but that is not a problem because head_32.S always uses 4KB > > pages. > > We use large pages FOR PAE kernels on x86-32 there > Do you mean we use large pages for PAE kernels on x86_32 in arch/x86/mm/init.c:init_memory_mapping? That wouldn't be a problem for this patch. The problem I am trying to solve occurs when head_64.S doesn't allocate any pte pages because it is using 2MB pages, while init_memory_mapping wants to use 4KB pages (for example because the user set CONFIG_DEBUG_PAGEALLOC). So on x86_32 is not going to be an issue because head_32.S doesn't use 2MB or 4MB pages as far as I can tell, even if the hardware supports them. Please correct me if I am wrong but I don't see any _PAGE_PSE in head_32.S. --8323329-559770896-1308841709=:12963-- -- 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/