From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756778Ab2HVM1Y (ORCPT ); Wed, 22 Aug 2012 08:27:24 -0400 Received: from moutng.kundenserver.de ([212.227.17.9]:53045 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753731Ab2HVM1U (ORCPT ); Wed, 22 Aug 2012 08:27:20 -0400 From: Arnd Bergmann To: Catalin Marinas Subject: Re: [PATCH v2 17/31] arm64: System calls handling Date: Wed, 22 Aug 2012 12:27:14 +0000 User-Agent: KMail/1.12.2 (Linux/3.5.0; KDE/4.3.2; x86_64; ; ) Cc: "linux-arch@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , Will Deacon References: <1344966752-16102-1-git-send-email-catalin.marinas@arm.com> <201208220756.31149.arnd@arndb.de> <20120822102953.GA24136@arm.com> In-Reply-To: <20120822102953.GA24136@arm.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201208221227.14274.arnd@arndb.de> X-Provags-ID: V02:K0:mnPKoTQ7oUVYqUkJ6eXrqvKz8O0POxEgnRn5QZJ7cxE VCG0rdQnmEB+SzFGPt+bOgRp/xfLX2FgDduxJVzYhvMajz02ZB Fem7AJ4n4kdG7qVpHP1eA2kwqySBvSSGRM5FbXlBW9QBlumb3I tpWmWm2tafKdVyFvPFzDWRbbgn0xjaFWivlIOzkqrTLft1AAuH GBd43W9Cicy4KdMFj40z/5uF50faIhBqHLyS9DDjlY1g1Z6221 lzspNuVfbFz1EjMrbynfACKZ2oACnVS2YzV9lOfQT4UNhyPY7w a8JIzUt6+gJbTHzI4qiCninlhNIz3MTj+J0ld+qBHeADROgNDP lm/pfpmZPE7qdquiEKqk= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 22 August 2012, Catalin Marinas wrote: > But what's more important - moving this wrapper to glibc causes issues > with the page size. We support both 4KB and 64KB pages on 64-bit systems > (the latter without compat support). The kernel is in a better position > to do the shift by a compile-time constant. Glibc would need to enquire > the actual page size to do the shift before calling sys_mmap_pgoff. If > we assume in glibc that the shift is always 12, we need another wrapper > in the kernel anyway for 64KB page configuration. So passing the offset > in bytes worked best for us. Right, the kernel interface should really be independent of the page size, as sys_mmap2 normally is, and sys_mmap2 is not provided here. Arnd