Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762794AbZDAIzw (ORCPT ); Wed, 1 Apr 2009 04:55:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755344AbZDAIzj (ORCPT ); Wed, 1 Apr 2009 04:55:39 -0400 Received: from hera.kernel.org ([140.211.167.34]:37465 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755472AbZDAIzi (ORCPT ); Wed, 1 Apr 2009 04:55:38 -0400 Message-ID: <49D32B96.3060102@kernel.org> Date: Wed, 01 Apr 2009 17:53:42 +0900 From: Tejun Heo User-Agent: Thunderbird 2.0.0.19 (X11/20081227) MIME-Version: 1.0 To: Martin Schwidefsky CC: Ingo Molnar , rusty@rustcorp.com.au, tglx@linutronix.de, x86@kernel.org, linux-kernel@vger.kernel.org, hpa@zytor.com, Paul Mundt , rmk@arm.linux.org.uk, starvik@axis.com, ralf@linux-mips.org, davem@davemloft.net, cooloney@kernel.org, kyle@mcmartin.ca, matthew@wil.cx, grundler@parisc-linux.org, takata@linux-m32r.org, benh@kernel.crashing.org, rth@twiddle.net, ink@jurassic.park.msu.ru, heiko.carstens@de.ibm.com Subject: Re: [GIT RFC] percpu: use dynamic percpu allocator as the default percpu allocator References: <1236671631-9305-1-git-send-email-tj@kernel.org> <20090316190132.7965a49a@skybase> <49C300D8.5080204@kernel.org> <49C8FAC4.6060508@kernel.org> <20090325122738.42d105b7@skybase> <49CA1AC3.9080908@kernel.org> <20090325122241.GE11571@elte.hu> <49CA2345.70204@kernel.org> <20090325141330.2717dc97@skybase> <49CA2FBF.9000207@kernel.org> <20090325142525.2d31c522@skybase> <49CA32F6.2030408@kernel.org> <20090331185431.72ff1707@skybase> <49D2B04D.4070604@kernel.org> <20090401101054.0a4b187d@skybase> <49D3231D.2040403@kernel.org> <20090401103257.12c2517e@skybase> In-Reply-To: <20090401103257.12c2517e@skybase> X-Enigmail-Version: 0.95.7 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (hera.kernel.org [127.0.0.1]); Wed, 01 Apr 2009 08:53:46 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1118 Lines: 33 Hello, Martin. Martin Schwidefsky wrote: > Yes, @GOTENT is a relocation against the GOT slot that contains the > address of the symbol. It is a special version of @GOT that uses larl > to locate the got slot directly without the need of a got base pointer. > > The code sequence with @GOT: > > larl %r12,_GLOBAL_OFFSET_TABLE_ > lg %r1,symbol@GOT(%r12) > > is equivalent to: > > larl %r1,symbol@GOTENT > lg %r1,0(%r1) > > The advantage of the second code sequence is that it need a single > register and the size of the GOT is not limited to 4K as in the first > example (the offset in an RX format instruction is limited to 12 bits - > but that is probably something you don't want to know ;-). Maybe we can build indirection pointer manually by twiddling with DEFINE_PER_CPU() in such a way that it doesn't have to distinguish symbols and variables? -- tejun -- 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/