From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752966Ab0CFNHs (ORCPT ); Sat, 6 Mar 2010 08:07:48 -0500 Received: from mr011.hansenet.de ([85.183.254.144]:42629 "EHLO mr011.hansenet.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752529Ab0CFNHr convert rfc822-to-8bit (ORCPT ); Sat, 6 Mar 2010 08:07:47 -0500 From: Thomas Koeller To: "Russell King - ARM Linux" Subject: Re: DMA using data buffer vmapped in kernel space Date: Sat, 6 Mar 2010 14:07:12 +0100 User-Agent: KMail/1.13.0 (Linux/2.6.32.5; KDE/4.4.0; x86_64; ; ) Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <201003042211.28569.thomas@koeller.dyndns.org> <20100304213634.GH13417@n2100.arm.linux.org.uk> In-Reply-To: <20100304213634.GH13417@n2100.arm.linux.org.uk> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 8BIT Message-Id: <201003061407.12698.thomas@koeller.dyndns.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am Donnerstag, 4. März 2010 22:36:34 schrieb Russell King - ARM Linux: > Cache maintainence is done using virtual addresses for L1, and > physical addresses for L2. There's the need for virtual addresses > to be translatable to physical addresses, which is only true for > the kernel direct mapped region (pages between PAGE_OFFSET and > high_memory). Isn't the mapping created by vmap() sufficient for the virt/phys translation? In which way is this case different from a buffer passed in from user space, where the constituent pages are not in the directly mapped kernel region either? tk