From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with SMTP id 9CC8C5F0001 for ; Mon, 20 Apr 2009 03:58:20 -0400 (EDT) Received: from mt1.gw.fujitsu.co.jp ([10.0.50.74]) by fgwmail5.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id n3K7xDG8013169 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Mon, 20 Apr 2009 16:59:14 +0900 Received: from smail (m4 [127.0.0.1]) by outgoing.m4.gw.fujitsu.co.jp (Postfix) with ESMTP id C28EE45DE4E for ; Mon, 20 Apr 2009 16:59:13 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (s4.gw.fujitsu.co.jp [10.0.50.94]) by m4.gw.fujitsu.co.jp (Postfix) with ESMTP id A188745DE4F for ; Mon, 20 Apr 2009 16:59:13 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id 6960FE08007 for ; Mon, 20 Apr 2009 16:59:13 +0900 (JST) Received: from ml13.s.css.fujitsu.com (ml13.s.css.fujitsu.com [10.249.87.103]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id 18425E08003 for ; Mon, 20 Apr 2009 16:59:13 +0900 (JST) From: KOSAKI Motohiro Subject: Re: Does get_user_pages_fast lock the user pages in memory in my case? In-Reply-To: <49EC0A24.6060307@gmail.com> References: <20090420141710.2509.A69D9226@jp.fujitsu.com> <49EC0A24.6060307@gmail.com> Message-Id: <20090420165529.61AB.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Date: Mon, 20 Apr 2009 16:59:12 +0900 (JST) Sender: owner-linux-mm@kvack.org To: Huang Shijie Cc: kosaki.motohiro@jp.fujitsu.com, Minchan Kim , linux-mm@kvack.org List-ID: > http://v4l2spec.bytesex.org/spec/r13696.htm > shows the vidioc_reqbufs(). It determines the method of IO : "Memory > Mapping or User Pointer I/O" > > The application developers can support any methodes of the Two, there is > no mandatory request to realize > both methods. For example, the Mplayer only support the "memory > maping" method ,and it does't support the "user pointer", > while the VLC supports both. I greped VIDIOC_REQBUFS on current tree. Almost driver has following check. if (rb->memory != V4L2_MEMORY_MMAP) return -EINVAL; IOW, almost one don't provide V4L2_MEMORY_USERPTR method. Thus, I think any userland application don't want use V4L2_MEMORY_USERPTR. I recommend you also return -EINVAL. I think we can't implement V4L2_MEMORY_USERPTR properly. it is mistake by specification. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org