From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42409) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fL8Bl-0003i3-Uf for qemu-devel@nongnu.org; Tue, 22 May 2018 10:22:58 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fL8Bl-0007Kk-2j for qemu-devel@nongnu.org; Tue, 22 May 2018 10:22:57 -0400 References: <20180521140402.23318-1-peter.maydell@linaro.org> <20180521140402.23318-15-peter.maydell@linaro.org> <47281818-f0cf-0ed1-c479-fbcaca5c5167@redhat.com> <595dcb89-3856-3755-e8db-7791c1374284@redhat.com> From: Auger Eric Message-ID: Date: Tue, 22 May 2018 16:22:48 +0200 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 14/27] iommu: Add IOMMU index concept to IOMMU API List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Maydell Cc: "patches@linaro.org" , QEMU Developers , qemu-arm , Paolo Bonzini , =?UTF-8?Q?Alex_Benn=c3=a9e?= , Richard Henderson On 05/22/2018 04:19 PM, Peter Maydell wrote: > On 22 May 2018 at 15:11, Auger Eric wrote: >> Hi Peter, >> >> On 05/22/2018 03:22 PM, Peter Maydell wrote: >>> How many substream IDs do we expect to see in practice? >> >> Spec says max 20 bits, matching the max size of the PASID > > Right, but do we actually expect to see transactions from > devices that use the whole 2^20 possible values, or will > they in practice mostly use 1..5, or somethnig else? An example given in the spec mentions 8. "An example would be a compute accelerator with 8 contexts that might each map to a different user process, but where the single device has common configuration meaning it must be assigned to a VM whole." Thanks Eric > > thanks > -- PMM >