From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:59162) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QcmIn-0007kR-Vv for qemu-devel@nongnu.org; Fri, 01 Jul 2011 18:35:11 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QcmIl-0005qB-Oj for qemu-devel@nongnu.org; Fri, 01 Jul 2011 18:35:09 -0400 Received: from mail-yx0-f173.google.com ([209.85.213.173]:63869) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QcmIl-0005os-GU for qemu-devel@nongnu.org; Fri, 01 Jul 2011 18:35:07 -0400 Received: by yxt3 with SMTP id 3so1333569yxt.4 for ; Fri, 01 Jul 2011 15:35:06 -0700 (PDT) Message-ID: <4E0E4B98.8050403@codemonkey.ws> Date: Fri, 01 Jul 2011 17:35:04 -0500 From: Anthony Liguori MIME-Version: 1.0 References: <9F6FE96B71CF29479FF1CDC8046E1503165EEB@039-SN1MPN1-003.039d.mgd.msft.net> <4E0DB945.4070203@codemonkey.ws> <20110701114301.08d0154b@schlenkerla.am.freescale.net> <201107011803.01887.paul@codesourcery.com> In-Reply-To: <201107011803.01887.paul@codesourcery.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] device assignment for embedded Power List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paul Brook Cc: Wood Scott-B07421 , "joerg.roedel@amd.com" , Alexander Graf , "qemu-devel@nongnu.org" , "blauwirbel@gmail.com" , Yoder Stuart-B08248 , "alex.williamson@redhat.com" , Scott Wood , "dwg@au1.ibm.com" , "armbru@redhat.com" On 07/01/2011 12:03 PM, Paul Brook wrote: >>> irq[0].guest_irq = "10" >>> >>> This should be independent of anything to do with device tree. This >>> would be useful for x86 too to assign platform devices (like the HPET). >> >> That's fine, as long as there's something layered on top of it for the case >> where we do want to reference something in the device tree. >> >> However, we'll need to address the question of what it means to say "irq >> 10" -- outside of PC-land there often isn't a global IRQ numberspace that >> isn't a fiction created by some software layer. Addressing this is one of >> the device tree's strengths. > > That's an entirely separate problem, thoug probably a prerequisite. > > Basically you should start by implementing full emulation of a device with > similar characteristics to the one you want to passthrough. If you want to model interrupt remapping, you have to model device relationships. If you cannot express the bus hierarchy/relationship then you cannot sanely model interrupt remapping. You can only really ever think about passing through an entire subtree of the device hierarchy. You can't have a partial subtree with some crazy hack logic to explain how the physical layer may remap interrupts. That's just asking for pain. Regards, Anthony Liguori