From mboxrd@z Thu Jan 1 00:00:00 1970 From: Julien Grall Subject: Re: [RFC 15/19] xen/arm: Reserve region in guest memory for device passthrough Date: Wed, 18 Jun 2014 19:33:38 +0100 Message-ID: <53A1DB82.6080709@linaro.org> References: <1402935486-29136-1-git-send-email-julien.grall@linaro.org> <1402935486-29136-16-git-send-email-julien.grall@linaro.org> <53A1AEEE.1030200@linaro.org> <1403105169.6568.87.camel@kazak.uk.xensource.com> <53A1D24D.2080406@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta4.messagelabs.com ([85.158.143.247]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1WxKg3-0007bw-NX for xen-devel@lists.xenproject.org; Wed, 18 Jun 2014 18:33:43 +0000 Received: by mail-wi0-f169.google.com with SMTP id hi2so8993105wib.0 for ; Wed, 18 Jun 2014 11:33:40 -0700 (PDT) In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Stefano Stabellini Cc: xen-devel@lists.xenproject.org, stefano.stabellini@citrix.com, Ian Campbell , tim@xen.org List-Id: xen-devel@lists.xenproject.org On 18/06/14 19:14, Stefano Stabellini wrote: >> For non-PCI passthrough this size will unlikely happen. We always map a >> matter of few pages per-device. >> >> I think this size is enough for the time being. I plan to revisit it for >> PCI passthrough where we will be able to allocate some of them after 4G. > > Modern GPUs can easily exceed 512MB and they work on ARM. If it's like on x86, passthrough GPUs may also require firmware. At least it looks like the case with some configuration on the Arndale, which doesn't have any SMMU. I'd like to make this series as simple as possible so we can get "quickly" a working solution to passthrough device with small amount of MMIO region. So if you don't mind I suggest to bump the amount of MMIO region to 1GB, I may need to shrink the first RAM bank, and think about bigger region support in a follow-up series. Regards, -- Julien Grall