From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 41jHZC71lQzF3GC for ; Sat, 4 Aug 2018 18:46:11 +1000 (AEST) Date: Sat, 4 Aug 2018 01:15:00 -0700 From: Christoph Hellwig To: "Michael S. Tsirkin" Cc: Christoph Hellwig , Benjamin Herrenschmidt , Will Deacon , Anshuman Khandual , virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, aik@ozlabs.ru, robh@kernel.org, joe@perches.com, elfring@users.sourceforge.net, david@gibson.dropbear.id.au, jasowang@redhat.com, mpe@ellerman.id.au, linuxram@us.ibm.com, haren@linux.vnet.ibm.com, paulus@samba.org, srikar@linux.vnet.ibm.com, robin.murphy@arm.com, jean-philippe.brucker@arm.com, marc.zyngier@arm.com Subject: Re: [RFC 0/4] Virtio uses DMA API for all devices Message-ID: <20180804081500.GA1455@infradead.org> References: <20180801083639.GF26378@infradead.org> <26c1d3d50d8e081eed44fe9940fbefed34598cbd.camel@kernel.crashing.org> <20180802182959-mutt-send-email-mst@kernel.org> <82ccef6ec3d95ee43f3990a4a2d0aea87eb45e89.camel@kernel.crashing.org> <20180802200646-mutt-send-email-mst@kernel.org> <20180802225738-mutt-send-email-mst@kernel.org> <20180803070507.GA1344@infradead.org> <20180803221634-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20180803221634-mutt-send-email-mst@kernel.org> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, Aug 03, 2018 at 10:17:32PM +0300, Michael S. Tsirkin wrote: > It seems reasonable to teach a platform to override dma-range > for a specific device e.g. in case it knows about bugs in ACPI. A platform will be able override dma-range using the dev->bus_dma_mask field starting in 4.19. But we'll still need a way how to a) document in the virtio spec that all bus dma quirks are to be applied b) a way to document in a virtio-related spec how the bus handles dma for Ben's totally fucked up hypervisor. Without that there is not way we'll get interoperable implementations.