From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:33537) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QoKNk-0007G1-Bt for qemu-devel@nongnu.org; Tue, 02 Aug 2011 15:12:01 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QoKNj-0007V7-CV for qemu-devel@nongnu.org; Tue, 02 Aug 2011 15:12:00 -0400 Received: from mx1.redhat.com ([209.132.183.28]:6795) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QoKNj-0007V0-1s for qemu-devel@nongnu.org; Tue, 02 Aug 2011 15:11:59 -0400 Message-ID: <4E384BF8.60204@redhat.com> Date: Tue, 02 Aug 2011 22:11:52 +0300 From: Avi Kivity MIME-Version: 1.0 References: <4E381EA7.2070809@redhat.com> <4E383C55.5050703@redhat.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] modelling omap_gpmc with the hierarchical memory API List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Maydell Cc: QEMU Developers On 08/02/2011 09:21 PM, Peter Maydell wrote: > On 2 August 2011 19:05, Avi Kivity wrote: > > On 08/02/2011 08:21 PM, Peter Maydell wrote: > >> So I think we just need a sysbus_mmio_get_memoryregion() > >> (and convert the devices I need to attach to use memory > >> regions, and live with not being able to attach unconverted > >> devices). > > > > I don't follow - why do we need get_memoryregion? who would call it? > > The machine model would call it. So you do something like > DeviceState *dev = qdev_create(NULL, "whatever"); > /* Note the parallel here to the existing > * sysbus_mmio_map(sysbus_from_qdev(dev), mmio_idx, addr); > */ > MemoryRegion *mr = > sysbus_mmio_get_memoryregion(sysbus_from_qdev(dev), mmio_idx); > omap_gpmc_attach(gpmc, 7, mr); This is where the gpmc provides the sysbus. It doesn't need to call get_memoryregion() on itself. > ie the machine model is where we wire up the subdevices > to the gpmc, and at the machine model level what you have is > a pointer to an entire device, so you need to be able to > convert the (sysbus*, mmio_index) tuple to a MemoryRegion*. I believe that it is in general unnecessary. A device hands its bus a memory region, and the bus does with it what it will (generally mapping it into a container, and presenting the container to a parent bus). get_memoryregion() implies a third party. > >> [That is, the only reason I'm passing SysBus objects around > >> is that at the moment that is the only useful abstraction we > >> have for saying "I'm an arbitrary device object and I provide > >> some GPIO pins and some memory mappable regions". MemoryRegion* > >> allows me to pass around a memory mappable region in a more > >> direct way than having to pass a (SysBus*, mmio_index) tuple.] > > > > I think I see. Perhaps you're describing qdev/MemoryRegion integration. > > I think qdev devices need to be able to expose MemoryRegions > as first class named 'properties' or 'plugs' or 'sockets' or > whatever we want to call them, yes. (Ditto gpio/irq, which at > the moment we can kind of expose but not by name.) Let's hope some sucker gets volunteered into it. -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.