From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753292AbXCMP5v (ORCPT ); Tue, 13 Mar 2007 11:57:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753290AbXCMP5v (ORCPT ); Tue, 13 Mar 2007 11:57:51 -0400 Received: from one.firstfloor.org ([213.235.205.2]:34228 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753292AbXCMP5u (ORCPT ); Tue, 13 Mar 2007 11:57:50 -0400 Date: Tue, 13 Mar 2007 16:57:47 +0100 From: Andi Kleen To: Rusty Russell Cc: Andi Kleen , Jeremy Fitzhardinge , "Marcin 'Qrczak' Kowalczyk" , linux-kernel@vger.kernel.org Subject: Re: _proxy_pda still makes linking modules fail Message-ID: <20070313155747.GA11162@one.firstfloor.org> References: <1173315479.12472.9.camel@qrnik> <45F49E0A.3090607@goop.org> <20070312094805.GA11644@one.firstfloor.org> <1173736726.10618.1.camel@localhost.localdomain> <1173767032.10618.43.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1173767032.10618.43.camel@localhost.localdomain> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 13, 2007 at 05:23:52PM +1100, Rusty Russell wrote: > On Tue, 2007-03-13 at 08:59 +1100, Rusty Russell wrote: > > On Mon, 2007-03-12 at 10:48 +0100, Andi Kleen wrote: > > > > Rusty's pda->per_cpu patch will deal with this once and for all; have > > > > > > Not on x86-64. > > > > Indeed. Perhaps it's time I join the modern world and compile a 64-bit > > kernel... > > > > Will prepare patches, > > No, I don't think I will. The PDA concept has gone too far in x86-64 to > be undone. In particular, it's been put in GCC 4.1 for > CONFIG_CC_STACKPROTECTOR, which assumes %gs:40 will give the stack > canary. Yes that was always ugly, but I don't know a better way. > For the record: the PDA should never have existed, that's what percpu > vars were supposed to be for. Something went wrong here 8( PDA predates per cpu. > The ideal solution has always been to use __thread, but no architecture > has yet managed it (I tried for i386, and it quickly caused unbearable I tried it too, but __thread is hopeless for kernel code > pain). On x86-64 that uses "%fs" on x86-64, not "%gs" as the kernel > does, but I might try that if I feel particularly masochistic soon... Then swapgs wouldn't work anymore (there is no swapfs) -Andi >