From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 64A161A08BC; Tue, 3 Feb 2026 21:11:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770153085; cv=none; b=hMhQbcshpd88fjKp4uEUPTvzUyqA2gJf6agpDBX27uSvEOxKfR+EsC1wafuaUbkpdf4bUmX4FeaQ54e5yG6jBZ3fyxHCKZrlmlmcasX3jySFzfD7Ex3euyLLOC1Zxz0vfJSXxRiCUNM/E8gk54vmIZ08lpHZSm/DbDkVdwZ1M5o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770153085; c=relaxed/simple; bh=NTZFLCwNdhv2d8qyf6fWYcj8dJBDdqRutv/GsTAS8sc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=F6Xcd0Ndo8PW4SOZ8oo98Al/I4HQcn0vzLtJ5ljHcpShMumXBDuqxMK6Fx1If5i8tqIUN6jpN2ED2dGaAWQKC58AKXJwvS5fP15iK5cvg3RCcIclJT3PAdl856N/bhwgt7w8OCah4/i0rLcfUPxqfBVpvs5vI52soySQUM7ZvQ8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=mZYARaR9; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="mZYARaR9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6AE1FC116D0; Tue, 3 Feb 2026 21:11:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770153085; bh=NTZFLCwNdhv2d8qyf6fWYcj8dJBDdqRutv/GsTAS8sc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=mZYARaR9dIYkgQvwN1EDBd+/hYZYzMJG8jy1T45b0PQ+YA+gurbCx69DLknkV7pG0 I+Kpa7d/vtOzKRMbTpfUkcpgwiDycPZnV9TZFFf3aYGh/I1SVzrIs7NrRCGdcG6WBH mzkvp6G2kP2TmmbqU0mn1WJ6c9XGqvyA7rxQr6h9UEZu1qips8BWJcUYTd1tyAHOqZ TM5y+JFaljjKvgz1Gr39S3lK4P4KGYoSu5OMxuoLPMsauBokgMB3G8BVUgCG2SLvhN AvErM1RXzDjzIobru+c0+ouXjJetm/T3RIjR7JXldXBR2VPg7ztrXXtZFyOoeoB1Cf 571dMrs6iXJKA== Date: Tue, 3 Feb 2026 23:11:19 +0200 From: Jarkko Sakkinen To: Laurent Pinchart Cc: Sakari Ailus , linux-media@vger.kernel.org, jani.nikula@linux.intel.com, anisse@astier.eu, oleksandr@natalenko.name, linux-integrity@vger.kernel.org, Mauro Carvalho Chehab , Hans Verkuil , Jacopo Mondi , Ricardo Ribalda , open list Subject: Re: [RFC PATCH v2] media: Virtual camera driver Message-ID: References: <20260202204425.2614054-1-jarkko@kernel.org> <20260203205742.GB11369@killaraus> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260203205742.GB11369@killaraus> On Tue, Feb 03, 2026 at 10:57:42PM +0200, Laurent Pinchart wrote: > Hello Jarkko, > > On Tue, Feb 03, 2026 at 03:36:59AM +0200, Jarkko Sakkinen wrote: > > On Tue, Feb 03, 2026 at 02:10:15AM +0200, Jarkko Sakkinen wrote: > > > On Tue, Feb 03, 2026 at 12:50:06AM +0200, Sakari Ailus wrote: > > > > On Mon, Feb 02, 2026 at 10:44:21PM +0200, Jarkko Sakkinen wrote: > > > > > Already a quick Google survey backs strongly that OOT drivers (e.g., > > > > > v4l2loopback) are the defacto solution for streaming phone cameras in > > > > > video conference calls, which puts confidential discussions at risk. > > > > > > > > As I think it was pointed out in review comments for v1, the reason behind > > > > using v4l2loopback is the use of a downstream driver, which itself is a > > > > source of a security risk. If I understand correctly, supporting this > > > > (proprietary/downstream vendor drivers) would be the main use case this > > > > driver serves? Should this downstream driver be upstreamed to alleviate the > > > > security risks, the need for v4l2loopback or similar drivers presumably > > > > disappears. > > > > > > My goal is not to proactively support proprietary drivers, and I don't > > > know how to measure such incentive or risk, when it comes to video > > > drivers. > > > > > > And besides there is e.g. FUSE. > > > > > > > Another of the downsides of such proprietary/downstream solutions is they > > > > can never be properly integrated into the Linux ecosystem so functionality > > > > will remain spotty (limited to specific systems and specific releases of > > > > specific distributions) at best. > > > > > > > > In other words, this driver appears to be orthogonal to solving either of > > > > the above two problems the proprietary/downstream solutions have. > > > > > > > > From the Open Source libcamera based camera software stack point of view > > > > there doesn't seem to be a need for v4l2loopback or another similar driver. > > > > The two main reasons for this is that (1) there's no need for glueing > > > > something separate together like this and (2) V4L2 isn't a great > > > > application interface for cameras -- use libcamera or Pipewire instead. > > > > > > While I get this argument isolated, it does not match the observed > > > reality, and does not provide tools to address the core issue. I > > > will be in my grave before I've fixed the world like you are > > > suggesting :-) > > I really hope we'll provide a solution much faster than that :-) > > > > Like, first off, where would I use libcamera or Pipewire? There's > > > no well-defined target other than kernel in this problem. > > PipeWire is becoming the de facto media server on desktop systems, for > both audio and video. It has been shipped by distributions for a while > for audio, and is the core component that allows screen capture (and > therefore screen sharing in video conferencing) on Wayland-based > systems. For video, PipeWire support has most notably been integrated in > WebRTC, used by both Firefox and Chrome. The number of applications > using PipeWire is growing, OBS has recently received support for > PipeWire sources for instance. If you need to use it in an application > that requires a V4L2 capture device, the pw-v4l2 script emulates the > V4L2 API to provide a quick stopgap measure until applications get > native PipeWire support. > > libcamera solves an orthogonal problem, which is control of raw camera > sensors and ISPs typically found in mobile and embedded devices, and now > increasingly in laptops as well (Intel IPU3, IPU4, IPU6 and IPU7). > Applications typically don't use libcamera directly, but interface it > with GStreamer (libcamerasrc element) or PipeWire (which has native > libcamera support). > > While I understand that libcamera and PipeWire may be quite new for a > large number of users, the ecosystem is moving in that direction, and > both projects are very active. Thanks for the information and I take this into account when/if considering any updates. The response is so informative that I need to purge this a bit (thank you for that) :-) This does not disregard your response but personally I'm not have huge a fan of LD_PRELOAD style compatibility wrappers. BR, Jarkko