From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mailfe09.c2i.net ([212.247.155.2]:54087 "EHLO swip.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754526Ab2CWHcQ convert rfc822-to-8bit (ORCPT ); Fri, 23 Mar 2012 03:32:16 -0400 Received: from [176.74.212.201] (account mc467741@c2i.net HELO laptop002.hselasky.homeunix.org) by mailfe09.swip.net (CommuniGate Pro SMTP 5.4.2) with ESMTPA id 79859403 for linux-media@vger.kernel.org; Fri, 23 Mar 2012 08:21:17 +0100 From: Hans Petter Selasky To: linux-media@vger.kernel.org Subject: Question about V4L2_MEMORY_USERPTR Date: Fri, 23 Mar 2012 08:19:45 +0100 MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT Message-Id: <201203230819.45385.hselasky@c2i.net> Sender: linux-media-owner@vger.kernel.org List-ID: Hi, I have a question about V4L2_MEMORY_USERPTR: >>From which context are the kernel's "copy_to_user()" functions called in relation to V4L2_MEMORY_USERPTR ? Can this be a USB callback function or is it only syscalls, like read/write/ioctl that are allowed to call "copy_to_user()" ? The reason for asking is that I am maintaining a userland port of the media tree's USB drivers for FreeBSD. At the present moment it is not allowed to call copy_to_user() or copy_from_user() unless the backtrace shows a syscall, so the V4L2_MEMORY_USERPTR feature is simply removed and disabled. I'm currently thinking how I can enable this feature. --HPS