Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932770AbZJFO20 (ORCPT ); Tue, 6 Oct 2009 10:28:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932755AbZJFO2Y (ORCPT ); Tue, 6 Oct 2009 10:28:24 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:59689 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932714AbZJFO2X (ORCPT ); Tue, 6 Oct 2009 10:28:23 -0400 Date: Tue, 6 Oct 2009 07:26:53 -0700 (PDT) From: Linus Torvalds X-X-Sender: torvalds@localhost.localdomain To: David Woodhouse cc: Jeff Chua , Valdis.Kletnieks@vt.edu, Tomasz Chmielewski , Daniel J Blueman , Byron Stanoszek , Dave Hansen , Hugh Dickins , Linux Kernel , Andrew Morton , Hugh Dickins Subject: Re: 2.6.32-rc3: low mem - only 378MB on x86_32 with 64GB. Why? In-Reply-To: <1254833974.14541.1306.camel@macbook.infradead.org> Message-ID: References: <1254833974.14541.1306.camel@macbook.infradead.org> User-Agent: Alpine 2.01 (LFD 1184 2008-12-16) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1293 Lines: 30 On Tue, 6 Oct 2009, David Woodhouse wrote: > On Mon, 2009-10-05 at 17:30 -0700, Linus Torvalds wrote: > > In fact, I wish more people did that, just so that we'd get better > > coverage of the 32-bit compat code. We occasionally find issues there, > > although I think it's getting rarer. > > We've been running PPC64 with 32-bit userspace for a long time, so most > of the issues with the 32-bit compat code ought to be dealt with. > > There may be a few arch-specific issues for x86_64/i386, but not many. The Intel Xorg guys used to do everything in 32-bit kernels because they were also testing that they didn't break compatibility (which is a big deal with that whole crazy DRM-in-kernel/direct-rendering-in-user-space thing) and seemingly didn't realize that the compat layer was _supposed_ to mean that they could run a 64-bit kernel and still have a working 32-bit land. It's driver interfaces like that that tend to break. ioctl's etc. But I have heard less noise about it lately, so I do think it's mostly working. Linus -- 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/