Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 9 Sep 2002 14:47:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 9 Sep 2002 14:47:29 -0400 Received: from antigonus.hosting.pacbell.net ([216.100.98.13]:23496 "EHLO antigonus.hosting.pacbell.net") by vger.kernel.org with ESMTP id ; Mon, 9 Sep 2002 14:47:27 -0400 Reply-To: From: "Imran Badr" To: "'Daniel Phillips'" , "'Andrew Morton'" Cc: , "'David S. Miller'" , Subject: RE: Calculating kernel logical address .. Date: Mon, 9 Sep 2002 11:49:02 -0700 Message-ID: <01a801c25831$913c5fd0$9e10a8c0@IMRANPC> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook CWS, Build 9.0.2416 (9.0.2911.0) In-Reply-To: Importance: Normal X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4807.1700 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1735 Lines: 57 -----Original Message----- From: linux-kernel-owner@vger.kernel.org [mailto:linux-kernel-owner@vger.kernel.org]On Behalf Of Daniel Phillips Sent: Monday, September 09, 2002 11:23 AM To: Andrew Morton; imran.badr@cavium.com Cc: root@chaos.analogic.com; 'David S. Miller'; linux-kernel@vger.kernel.org Subject: Re: Calculating kernel logical address .. On Monday 09 September 2002 20:08, Andrew Morton wrote: > Imran Badr wrote: > > > > The virt_to_bus() macro would work only for kernel logical addresses. I am > > trying to find a portable way to figure out the kernel logical address of a > > user buffer so that I could use virt_to_bus() for DMA. The user address is > > mmap'ed from kmalloc'ed buffer in the mmap() entry of my driver. Now when > > the user wants to send this data to the PCI device, it makes an ioctl call > > and give the user address to the driver. Now driver has to figure out the > > kernel logical address for DMA. > > You can obtain this info by walking the user's pagetables with > get_user_pages(). That give `struct page' pointers, with which > all things are possible. >As long as you can be sure they won't spontaneously vanish on you. >-- >Daniel >- >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/ down(¤t->mm->mmap_sem) would help. Imran. - 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/