From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 59FFB18732B; Thu, 3 Apr 2025 07:24:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743665076; cv=none; b=ZKr6ZNRpTF7jdtPbsUN7m1MR9ZIe3sqqJUJDHpzvNkISJwAA080tElrxiMMWrPwb/Xildb8YJv6wKOpctzk6wRHtgC7NA/j53x0sSgC9Re4BD0BxIfOzzCstxulNz8V+h9Tg0pgvNFtBnh0oKu8mCTdoGgsf7iney/Y5/P4AG8Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743665076; c=relaxed/simple; bh=06ghVNU5N3saoruBnttTeD8smgvYZomjIXvnQDjTLEc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=RaNJFDxhNEG39oblaaVDYoovYeZ1wAMkdz+452KZh5ZS9xfkPrORpN7KKjkUWTwuCb1JfTAsLpKH8Y0JEga/j8W5xPa+gmW5DV+EMVbtNE6oRe1cIjpV0TeSxKzlM8QzujjwO4DcaxKIh1lnqUD9pB9HxslOx5eDdeheSVbJ0Zc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=V8Nm8y44; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="V8Nm8y44" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=mZJoRgl7tKUmuHw/xIDGXaeA0kg35+tgF4aTMSGhxZI=; b=V8Nm8y44qTUMr/32bDu8BfdFLv J/xl3p//WZXV00K78sdsCVF30rB8tCwwgtI76WVn2D//TsALfZDThwfJUy566w3c7UCunE8g5SNOG xwO+sg/yboDd/DyqOOys0fx2m3U5jLlDfXyJEawyreTy9RfWgr8CMhvYTxRhkVWuq9LFYlmXVW2i7 pHGuTLmmlIck1Qd1UE7QVGAqrAvaNj9ZZ81hC6mH08Kl7GJ81bIw9YwCIaI2XPqjX77wpj8+ZMAJ9 12puYOD09T+EHuMXeCn5QFgdbthJ7kv6r4648hRYrf84LgkRQJS6DxzCeQI79c/njfwrnNIJN3rAy ERTNdrSg==; Received: from hch by bombadil.infradead.org with local (Exim 4.98.1 #2 (Red Hat Linux)) id 1u0EwE-0000000867w-1zgG; Thu, 03 Apr 2025 07:24:34 +0000 Date: Thu, 3 Apr 2025 00:24:34 -0700 From: Christoph Hellwig To: David Woodhouse Cc: virtio-comment@lists.linux.dev, mst@redhat.com, hch@infradead.org, Claire Chang , linux-devicetree , Rob Herring , =?iso-8859-1?Q?J=F6rg?= Roedel , iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, graf@amazon.de Subject: Re: [RFC PATCH 1/3] content: Add VIRTIO_F_SWIOTLB to negotiate use of SWIOTLB bounce buffers Message-ID: References: <20250402112410.2086892-1-dwmw2@infradead.org> <20250402112410.2086892-2-dwmw2@infradead.org> 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: <20250402112410.2086892-2-dwmw2@infradead.org> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Wed, Apr 02, 2025 at 12:04:45PM +0100, David Woodhouse wrote: > Define a VIRTIO_F_SWIOTLB feature which allows the device and driver to > agree on the use of the SWIOTLB, if present. This enables the device to > refuse to operate further if the driver does not support the SWIOTLB > requirement expressed in the device-tree. This makes no sense whatsoever. Swiotlb is a Linux guest implementation detail, virtio is a transport protocol. Mixing them in the same spec doesn't even compute. Please describe the actual on the wire semantics you want, and don't use the term swiotlb.