Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 21 Aug 2002 01:25:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 21 Aug 2002 01:25:58 -0400 Received: from lmail.actcom.co.il ([192.114.47.13]:7835 "EHLO lmail.actcom.co.il") by vger.kernel.org with ESMTP id ; Wed, 21 Aug 2002 01:25:57 -0400 Subject: RE: Alloc and lock down large amounts of memory From: Gilad Ben-Yossef To: Bhavana Nagendra Cc: Mike Galbraith , linux-kernel@vger.kernel.org In-Reply-To: <23B25974812ED411B48200D0B774071701248C6A@exchusa03.intense3d.com> References: <23B25974812ED411B48200D0B774071701248C6A@exchusa03.intense3d.com> Content-Type: text/plain Content-Transfer-Encoding: 7bit X-Mailer: Ximian Evolution 1.0.8 Date: 21 Aug 2002 08:29:52 +0300 Message-Id: <1029907792.19202.25.camel@gby.benyossef.com> Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1039 Lines: 30 On Tue, 2002-08-20 at 23:08, Bhavana Nagendra wrote: > > > > Curiosity: why do you want to do device DMA buffer > > allocation from userland? > > Gilad, I looked at mm/memory.c and map_user_kiobuf() lets me > map user memory into kernel memory and pins it down. A scatter > gatter mapping (say, pci_map_sg()) will create a seemingly > contiguous buffer for DMA purposes. Does that sound right to you? Can your device actually use scatter gather (has 'virtual bus addresses' or can get the buffer in several chunks?) Can the device actually DMA all the memory in the system? In short, I have no idea. :-) Gilad. -- Gilad Ben-Yossef http://benyossef.com "Money talks, bullshit walks and GNU awks." -- Shachar "Sun" Shemesh, debt collector for the GNU/Yakuza - 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/