From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Tue, 29 Aug 2006 14:50:32 +0100 (BST) Received: from localhost.localdomain ([127.0.0.1]:33256 "EHLO dl5rb.ham-radio-op.net") by ftp.linux-mips.org with ESMTP id S20039460AbWH2Nua (ORCPT ); Tue, 29 Aug 2006 14:50:30 +0100 Received: from denk.linux-mips.net (denk.linux-mips.net [127.0.0.1]) by dl5rb.ham-radio-op.net (8.13.7/8.13.7) with ESMTP id k7TDotSp031401; Tue, 29 Aug 2006 14:50:55 +0100 Received: (from ralf@localhost) by denk.linux-mips.net (8.13.7/8.13.7/Submit) id k7TDotoc031400; Tue, 29 Aug 2006 14:50:55 +0100 Date: Tue, 29 Aug 2006 14:50:55 +0100 From: Ralf Baechle To: Peter Watkins Cc: linux-mips@linux-mips.org Subject: Re: [PATCH] 64K page size Message-ID: <20060829135055.GB29289@linux-mips.org> References: <44EC7125.7000000@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <44EC7125.7000000@gmail.com> User-Agent: Mutt/1.4.2.1i Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 12458 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: ralf@linux-mips.org Precedence: bulk X-list: linux-mips On Wed, Aug 23, 2006 at 11:15:49AM -0400, Peter Watkins wrote: > There are a number of changes required to support larger page sizes, but > this one I thought worth sending up right away. > > The code in pgtable-64.h assumes TASK_SIZE is always bigger than a first > level PGDIR_SIZE. This is not the case for 64K pages, where task size is > 40 bits (1TB) and a pgd entry can map 42 bits. This leads to > USER_PTRS_PER_PGD being zero for 64K pages. Do you actually need large address space? The kernel could allow 2, 3 and 4-level pagetables easily but doesn't give that choice currently. Ralf