From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH v2 17/31] arm64: System calls handling Date: Wed, 22 Aug 2012 12:27:14 +0000 Message-ID: <201208221227.14274.arnd@arndb.de> References: <1344966752-16102-1-git-send-email-catalin.marinas@arm.com> <201208220756.31149.arnd@arndb.de> <20120822102953.GA24136@arm.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: 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 In-Reply-To: <20120822102953.GA24136@arm.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Catalin Marinas Cc: "linux-arch@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , Will Deacon 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 From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Wed, 22 Aug 2012 12:27:14 +0000 Subject: [PATCH v2 17/31] arm64: System calls handling In-Reply-To: <20120822102953.GA24136@arm.com> References: <1344966752-16102-1-git-send-email-catalin.marinas@arm.com> <201208220756.31149.arnd@arndb.de> <20120822102953.GA24136@arm.com> Message-ID: <201208221227.14274.arnd@arndb.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.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