From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:35166) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QN67a-0003m6-1K for qemu-devel@nongnu.org; Thu, 19 May 2011 12:30:47 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QN67Z-0006Eq-0E for qemu-devel@nongnu.org; Thu, 19 May 2011 12:30:45 -0400 Received: from thoth.sbs.de ([192.35.17.2]:27158) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QN67Y-0006Ee-NG for qemu-devel@nongnu.org; Thu, 19 May 2011 12:30:44 -0400 Message-ID: <4DD545B2.70705@siemens.com> Date: Thu, 19 May 2011 18:30:42 +0200 From: Jan Kiszka MIME-Version: 1.0 References: <4DD51FDA.3010107@codemonkey.ws> <4DD520ED.8010606@redhat.com> <4DD5260A.1080309@codemonkey.ws> <4DD5272F.5000003@siemens.com> <4DD52848.6030102@codemonkey.ws> <4DD52910.4080106@siemens.com> <4DD52B0E.2080604@codemonkey.ws> <4DD52BF2.2080506@redhat.com> <20110519161731.GA27310@redhat.com> <4DD5446A.6030003@siemens.com> <20110519162805.GC27310@redhat.com> In-Reply-To: <20110519162805.GC27310@redhat.com> 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: Gleb Natapov Cc: Avi Kivity , qemu-devel On 2011-05-19 18:28, Gleb Natapov wrote: > On Thu, May 19, 2011 at 06:25:14PM +0200, Jan Kiszka wrote: >> On 2011-05-19 18:17, Gleb Natapov wrote: >>> On Thu, May 19, 2011 at 05:40:50PM +0300, Avi Kivity wrote: >>>> On 05/19/2011 05:37 PM, Anthony Liguori wrote: >>>>> >>>>> So.... do you do: >>>>> >>>>> isa_register_region(ISABus *bus, MemoryRegion *mr, int priority) >>>>> { >>>>> chipset_register_region(bus->chipset, mr, priority + 1); >>>>> } >>>>> >>>>> I don't really understand how you can fold everything into one >>>>> table and not allow devices to override their parents using >>>>> priorities. >>>> >>>> Think of how a window manager folds windows with priorities onto a >>>> flat framebuffer. >>>> >>>> You do a depth-first walk of the tree. For each child list, you >>>> iterate it from the lowest to highest priority, allowing later >>>> subregions override earlier subregions. >>>> >>> And how you set those priorities in a sensible way? Why two device on a >>> PCI bus will want to register their memory region with anything but >>> highest priority? And if you let PCI subsystem to assign priorities how >>> it will coordinate with ISA subsystem/memory controller what priorities >>> to assign to get meaningful system? >> >> Priorities >default will only be used for explicit overlays, e.g. RAM >> over MMIO in PAM regions. Non-default priorities won't be assigned to >> normal PCI bars or any other device's region. >> > That does not explain who and how assign those priorities in globally > meaningful way. There are no global priorities. Priorities are only used inside each level of the memory region hierarchy to generate a resulting, flattened view for the next higher level. At that level, everything imported from below has the default prio again, ie. the lowest one. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux