From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e32.co.us.ibm.com (e32.co.us.ibm.com [32.97.110.150]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e32.co.us.ibm.com", Issuer "Equifax" (verified OK)) by ozlabs.org (Postfix) with ESMTP id 8892067BEB for ; Thu, 28 Sep 2006 02:50:39 +1000 (EST) Received: from d03relay04.boulder.ibm.com (d03relay04.boulder.ibm.com [9.17.195.106]) by e32.co.us.ibm.com (8.13.8/8.12.11) with ESMTP id k8RGoabI025245 for ; Wed, 27 Sep 2006 12:50:36 -0400 Received: from d03av01.boulder.ibm.com (d03av01.boulder.ibm.com [9.17.195.167]) by d03relay04.boulder.ibm.com (8.13.6/8.13.6/NCO v8.1.1) with ESMTP id k8RGoa4D252064 for ; Wed, 27 Sep 2006 10:50:36 -0600 Received: from d03av01.boulder.ibm.com (loopback [127.0.0.1]) by d03av01.boulder.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id k8RGoZww028245 for ; Wed, 27 Sep 2006 10:50:35 -0600 Subject: iommu hypervisor hypothetical From: John Rose To: Santiago Leon , benh@kernel.crashing.org, External List Content-Type: text/plain Message-Id: <1159375671.19103.3.camel@sinatra.austin.ibm.com> Mime-Version: 1.0 Date: Wed, 27 Sep 2006 11:47:51 -0500 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Suppose the hypervisor added new failure codes for the hcall that does tce_build(). Suppose that the device driver needed to expect such failures when alloc_[coherent,consistent] is not successful, and handle that case accordingly. Is this something we can accommodate without rewriting the iommu stuff for various platforms? All these functions in machdep.h are defined to return NULL. Is this because we haven't had a reasonable expectation of failure, or because device drivers _have_ to assume success for such operations? Thanks- John