From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:34760) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QN45b-000360-UJ for qemu-devel@nongnu.org; Thu, 19 May 2011 10:20:36 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QN45a-0006Uh-LV for qemu-devel@nongnu.org; Thu, 19 May 2011 10:20:35 -0400 Received: from david.siemens.de ([192.35.17.14]:32859) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QN45a-0006UN-As for qemu-devel@nongnu.org; Thu, 19 May 2011 10:20:34 -0400 Message-ID: <4DD5272F.5000003@siemens.com> Date: Thu, 19 May 2011 16:20:31 +0200 From: Jan Kiszka MIME-Version: 1.0 References: <4DD3D236.90708@siemens.com> <4DD3D95E.2060105@redhat.com> <4DD3E1B3.3020405@siemens.com> <4DD3E47F.9060104@redhat.com> <4DD3E782.8090208@siemens.com> <4DD3E8D6.6090807@redhat.com> <20110519090851.GD28399@redhat.com> <4DD4DE8E.8030402@redhat.com> <20110519091404.GE28399@redhat.com> <4DD5029D.6000700@redhat.com> <20110519115405.GG28399@redhat.com> <4DD505C4.6010604@redhat.com> <4DD50B17.7000205@siemens.com> <4DD511FB.3080901@redhat.com> <4DD51413.1050202@siemens.com> <4DD51468.7050509@redhat.com> <4DD51531.7000701@siemens.com> <4DD515F9.1020902@redhat.com> <4DD51A82.7060205@siemens.com> <4DD51B64.8000306@redhat.com> <4DD51FDA.3010107@codemonkey.ws> <4DD520ED.8010606@redhat.com> <4DD5260A.1080309@codemonkey.ws> In-Reply-To: <4DD5260A.1080309@codemonkey.ws> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [RFC] Memory API List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: Avi Kivity , Gleb Natapov , qemu-devel On 2011-05-19 16:15, Anthony Liguori wrote: > On 05/19/2011 08:53 AM, Avi Kivity wrote: >> On 05/19/2011 04:49 PM, Anthony Liguori wrote: >>> On 05/19/2011 08:30 AM, Avi Kivity wrote: >>>> On 05/19/2011 04:26 PM, Jan Kiszka wrote: >>>>> On 2011-05-19 15:07, Avi Kivity wrote: >>> >>>>> And when introducing hierarchical registration, we will have to go >>>>> through all of this once again. Plus the API may have to be changed >>>>> again if it does not fulfill all requirements of the hierarchical >>>>> region >>>>> management. And we have no proof that it allows an efficient core >>>>> implementation. >>>> >>>> This API *is* hierarchical registration. v2 will (hopefully) prove that >>>> it can be done efficiently. >>> >>> We also need hierarchical dispatch. Priorities are just a weak attempt >>> to emulate hierarchical dispatch but I don't think there's an >>> improvement over a single dispatch table. >>> >>> Hierarchical dispatch is simpler. You just need a simple list at each >>> bus. >>> >> >> The API itself says nothing about whether the hierarchy is evaluated at >> run-time or registration time. > > Except for priorities. > > If you've got a hierarchy like: > > - CPU:0 > - i440fx:1 > - PIIX3:2 > - ISA:3 > - DeviceA > - PCI:2 > - DeviceB > > In your model, the default priorities are as shown, but nothing stops > DeviceB from registering with a priority of 0 which means it can > intercept accesses that would normally go to the i440fx. Priorities would be local, so the normal tree would look like this: - CPU:0 - i440fx:0 - PIIX3:0 - DeviceA - PCI-DeviceB:0 If the i440fx would like to map something different over DeviceA (or parts of it), it would create a region of prio 1 or higher. The same would happen at CPU-level with SMRAM when SMM is entered. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux