Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752966Ab2JJPtN (ORCPT ); Wed, 10 Oct 2012 11:49:13 -0400 Received: from mail-bk0-f46.google.com ([209.85.214.46]:38321 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751655Ab2JJPtH (ORCPT ); Wed, 10 Oct 2012 11:49:07 -0400 MIME-Version: 1.0 In-Reply-To: <20121010141707.GH4005@phenom.dumpdata.com> References: <1349757558-10856-1-git-send-email-yinghai@kernel.org> <1349757558-10856-4-git-send-email-yinghai@kernel.org> <20121009160133.GF7639@phenom.dumpdata.com> <20121010141707.GH4005@phenom.dumpdata.com> Date: Wed, 10 Oct 2012 08:49:05 -0700 X-Google-Sender-Auth: Y9aN0qz9jYDriS-1z39PQUty2ww Message-ID: Subject: Re: [PATCH 03/10] x86, mm: get early page table from BRK From: Yinghai Lu To: Konrad Rzeszutek Wilk Cc: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Jacob Shin , Tejun Heo , Stefano Stabellini , linux-kernel@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 863 Lines: 21 On Wed, Oct 10, 2012 at 7:17 AM, Konrad Rzeszutek Wilk wrote: > On Tue, Oct 09, 2012 at 06:03:33PM -0700, Yinghai Lu wrote: >> good point, i add one line comment to the revised patch. >> >> +/* need 3 4k for initial PMD_SIZE, 4k for 0-ISA_END_ADDRESS */ > > Can you explain the math please? It sounds like this is based on > the assumption that this you are using huge pages. But what if you > are not? What if you can only do 4KB pages? yes that is some extreme case: assume that 2M range is [2T-2M, 2T), one page for PGD-[2T-512g, 2T), one for PUD - [2T-1G, 2T), and one for PMD -: [2T-2M, 2T) -- 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/