From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oi1-f169.google.com (mail-oi1-f169.google.com [209.85.167.169]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 922331B150A for ; Wed, 31 Jul 2024 13:15:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.169 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722431753; cv=none; b=UhAHG9/6glkLWF0DBwQr8YSf7RTb2/R4O2XXAw0TEDeNZPok+vsvNVHnk3vPwgUDUyDFe1fHD8zip1gkH6E87o6TIfZrFNO4JjqbkxjJKY+keU2Rc2VKt2Xz5hfMhtcl428iqbA3XyIYGTtmY0Z3knxjarKXBQ0YxWKhF3nh9cU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722431753; c=relaxed/simple; bh=0qkwQ0MmMQBMbBAsVU4qO+QelNoT7Eax5wkEMJX06Ic=; h=MIME-Version:References:In-Reply-To:From:Date:Message-ID:Subject: To:Cc:Content-Type; b=NUeOlWBGhMstOwfU8wmQM6NB9JCVmzpxrInP4aA2/rGBydS9vLZawzlMVR7xFW7zsGkUQF3Baj1CY5Okd5039KOBIMvEc815BRfeXvn2t7YTQi01n/c+m2yi6bWRjdY6zI4UBNEM/ZTNe3CSobBZZknZjMn6QyEbvKi7ydvuMks= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ffwll.ch; spf=none smtp.mailfrom=ffwll.ch; dkim=pass (1024-bit key) header.d=ffwll.ch header.i=@ffwll.ch header.b=jUtWbJir; arc=none smtp.client-ip=209.85.167.169 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ffwll.ch Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=ffwll.ch Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ffwll.ch header.i=@ffwll.ch header.b="jUtWbJir" Received: by mail-oi1-f169.google.com with SMTP id 5614622812f47-3db1d48083dso517410b6e.3 for ; Wed, 31 Jul 2024 06:15:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; t=1722431750; x=1723036550; darn=lists.linux.dev; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=Ean7sSS19FfLz1vX4VUsoj/SGZS7nDauOxzT51mpNiw=; b=jUtWbJirSXuCSJ5psAMzcn/WiK9xiskseTwaF3C3aDdZG6V51PEsJ4XIgZfgEi1yRG ErFQlxVUJ0xvMg3KHKkKSwKzdqtxTtGemedcccGXgaLbILnLnh5m41SpdhDekw3uCUeq 46XaYZRKZ22Z+Ie6olki9uAia2nxSS9/mzGxA= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1722431750; x=1723036550; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=Ean7sSS19FfLz1vX4VUsoj/SGZS7nDauOxzT51mpNiw=; b=AaqnyqYvzZodGycyo/JsAZdJt2fp6akfN3Bn4J+hFQe0V7KjiNCI3GLESZhIznzHrc 5DX1JXqvY1u/840rlEfUH8tbvsJriiRxQ96QgKxTEY/+REYDh5ICdqq20tcPmI8OFKk8 Uy0hSrXrQPzIcbsWrkjXx5El2DhzeYnhXovDbgNB8P8IXjVy2qTm1V//GLI4q7nhH/nq 5sb7FZNRO47Q+PBgs7Q6DicwPRChd1V7S+uczowfbMhSF8Ejz6It/8CoZuAeUfGvpp5e HCtu4qzgg1mG6PWwr4H7Ax5DxHEbmlkFfo6EoB1mh1oxWKF/qcuztTAJAxhYQSoDCZzZ 92xg== X-Forwarded-Encrypted: i=1; AJvYcCWTMXZbdjqZ0dgxOUGiMbzXC1fMs6h0Zu4NTW0M8y1XWnfdiuyJ2hgvtaFlr3Ull69+ginTic3IUzZX6DLAW2ZKNECqq2a0rg== X-Gm-Message-State: AOJu0YwloxJAt4+k2P98X7/F6f/zfOv9tN1BmKYpMIYCqBL79PygfVVP sNA9MiPHCCfkU3tdImN6ezdyDVSaq6geAFEVajIEGLwjxQF4+g9vuzAvNZb/rSeAy6sU5LRr3Bz mhGbkRR37TaZ/i9dGP/90yzlqubb9z+sum0iKBQ== X-Google-Smtp-Source: AGHT+IFRXAg1VLup8Q5b6YTsFY3klhFNVf83mG/k3C+eDgnwe1Nu09nxYmzuT2rekf8aCOwmOO+FFi5mCTeogw6pn3w= X-Received: by 2002:a05:6871:9c01:b0:260:f1c4:2fdb with SMTP id 586e51a60fabf-264c4479917mr11725728fac.8.1722431750651; Wed, 31 Jul 2024 06:15:50 -0700 (PDT) Precedence: bulk X-Mailing-List: ksummit@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20240721192530.GD23783@pendragon.ideasonboard.com> <20240722111834.GC13497@pendragon.ideasonboard.com> <20240725200142.GF14252@pendragon.ideasonboard.com> <20240726105936.GC28621@pendragon.ideasonboard.com> <20240728171800.GJ30973@pendragon.ideasonboard.com> In-Reply-To: From: Daniel Vetter Date: Wed, 31 Jul 2024 15:15:39 +0200 Message-ID: Subject: Re: [MAINTAINERS SUMMIT] Device Passthrough Considered Harmful? To: Sakari Ailus Cc: Ricardo Ribalda Delgado , Laurent Pinchart , Dan Williams , James Bottomley , ksummit@lists.linux.dev, linux-cxl@vger.kernel.org, linux-rdma@vger.kernel.org, netdev@vger.kernel.org, jgg@nvidia.com Content-Type: text/plain; charset="UTF-8" On Wed, 31 Jul 2024 at 13:55, Sakari Ailus wrote: > This is also very different from GPUs or accel devices that are built to be > user-programmable. If I'd compare ISPs to different devices, then the > closest match would probably be video codecs -- which also use V4L2. Really just aside, but I figured I should correct this. DRM supports plenty of video codecs. They're all tied to gpus, but the real reason really is that the hw has decent command submission support so that running the entire codec in userspace except the basic memory and batch execution and synchronization handling in the kernel is a feasible design. And actually good, because your kernel wont ever blow up trying to parse complex media formats because it just doesn't. -Sima -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch