From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58227) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fuXsg-00041d-8F for qemu-devel@nongnu.org; Tue, 28 Aug 2018 02:53:39 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fuXsY-0002YR-Ez for qemu-devel@nongnu.org; Tue, 28 Aug 2018 02:53:37 -0400 Received: from mail-wm0-x234.google.com ([2a00:1450:400c:c09::234]:37841) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1fuXsW-0002Wr-Ed for qemu-devel@nongnu.org; Tue, 28 Aug 2018 02:53:30 -0400 Received: by mail-wm0-x234.google.com with SMTP id n11-v6so721960wmc.2 for ; Mon, 27 Aug 2018 23:53:28 -0700 (PDT) References: <1533793434-7614-1-git-send-email-whois.zihan.yang@gmail.com> <20180827070406.t525gr43qpu7wpsj@sirius.home.kraxel.org> <5f5dc082-7053-d6b9-b01f-fffba1847ba5@gmail.com> <20180828060752.mmsd7x7uobqm2gsr@sirius.home.kraxel.org> From: Marcel Apfelbaum Message-ID: <8b232ca6-4643-24c7-d93d-589a452d0785@gmail.com> Date: Tue, 28 Aug 2018 09:53:24 +0300 MIME-Version: 1.0 In-Reply-To: <20180828060752.mmsd7x7uobqm2gsr@sirius.home.kraxel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Subject: Re: [Qemu-devel] [SeaBIOS] [RFC v2 0/3] Support multiple pci domains in pci_device List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gerd Hoffmann Cc: Zihan Yang , "Michael S. Tsirkin" , qemu-devel@nongnu.org, seabios@seabios.org Hi Gerd, On 08/28/2018 09:07 AM, Gerd Hoffmann wrote: > Hi, > >> Since we will not use all 256 buses of an extra PCI domain, >> I think this space will allow us to support more PCI domains. > Depends on the use case I guess. If you just need many pcie devices > this probably doesn't help. If you want them for numa support then yes, > more domains with less devices each can be useful then. We already support multiple NUMA nodes. We want more devices. Still, having 4x number of devices we previously supported is a good step forward. > >> How will the flow look like ? >> >> 1. QEMU passes to SeaBIOS information of how many extra >>    PCI domains needs, and how many buses per domain. >>    How it will pass this info? A vendor specific capability, >>    some PCI registers or modifying extra-pci-roots fw_cfg file? > Where is the pxb-pcie device? 0000:$somewhere? Or $domain:00:00.0? 0000:$somewhere (On PCI domain 0) >> 2. SeaBIOS assigns the address for each PCI Domain >> and >>     returns the information to QEMU. >>     How it will do that? Some pxb-pcie registers? Or do we model >>     the MMCFG like a PCI BAR? > If we can access pxb-pcie registers before configuring MMCFG then yes, > we should use pxb-pcie registers for that. Yes, we can. Thanks Gerd! Marcel > > cheers, > Gerd >