From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Travis Subject: Re: [patch 04/41] cpu ops: Core piece for generic atomic per cpu operations Date: Tue, 17 Jun 2008 07:21:04 -0700 Message-ID: <4857C850.103@sgi.com> References: <20080530035620.587204923@sgi.com> <200806152033.02891.rusty@rustcorp.com.au> <200806171024.40662.rusty@rustcorp.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from relay1.sgi.com ([192.48.171.29]:55332 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1757386AbYFQOVK (ORCPT ); Tue, 17 Jun 2008 10:21:10 -0400 In-Reply-To: <200806171024.40662.rusty@rustcorp.com.au> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Rusty Russell Cc: Christoph Lameter , Nick Piggin , Martin Peschke , Andrew Morton , linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, David Miller , Eric Dumazet , Peter Zijlstra Rusty Russell wrote: > On Tuesday 17 June 2008 00:52:08 Christoph Lameter wrote: >> On Sun, 15 Jun 2008, Rusty Russell wrote: >>>> 3. Some hooks for arches to override particular behavior as needed. >>>> F.e. IA64 allocates percpu structures in a special way. x86_64 >>>> needs to do some tricks for the pda etc etc. >>> IA64 is going to need some work, since dynamic percpu addresses won't be >>> able to use their pinned TLB trick to get the local version. >> The ia64 hook could simply return the address of percpu area that >> was reserved when the per node memory layout was generated (which happens >> very early during node bootstrap). > > Apologies, this time I read the code. I thought IA64 used the pinned TLB area > to access per-cpu vars under some circumstances, but they only do that via an > arch-specific macro. > > So creating new congruent mappings to expand the percpu area(s) is our main > concern now? > > Rusty. Not exactly. Getting the system to not panic early in the boot (before x86_64_start_kernel()) is the primary problem right now. This happens in the tip tree with the change to use zero-based percpu offsets. It gets much farther on the linux-next tree. Thanks, Mike