From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46984) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dZeW5-0007E6-Um for qemu-devel@nongnu.org; Mon, 24 Jul 2017 10:39:27 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dZeW4-000574-W1 for qemu-devel@nongnu.org; Mon, 24 Jul 2017 10:39:26 -0400 Received: from mail-pf0-x233.google.com ([2607:f8b0:400e:c00::233]:34335) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1dZeW4-00054o-Oq for qemu-devel@nongnu.org; Mon, 24 Jul 2017 10:39:24 -0400 Received: by mail-pf0-x233.google.com with SMTP id q85so47757058pfq.1 for ; Mon, 24 Jul 2017 07:39:23 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <1500889352.15837.7.camel@redhat.com> References: <1500761510-1556-1-git-send-email-zuban32s@gmail.com> <1500761510-1556-5-git-send-email-zuban32s@gmail.com> <20170723054445-mutt-send-email-mst@kernel.org> <1500889352.15837.7.camel@redhat.com> From: Alexander Bezzubikov Date: Mon, 24 Jul 2017 17:39:21 +0300 Message-ID: Content-Type: text/plain; charset="UTF-8" Subject: Re: [Qemu-devel] [RFC PATCH v2 4/4] pci: enable RedHat PCI bridges to reserve additional buses on PCI init List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gerd Hoffmann Cc: "Michael S. Tsirkin" , seabios@seabios.org, Marcel Apfelbaum , Kevin OConnor , lersek@redhat.com, qemu-devel@nongnu.org, Konrad Rzeszutek Wilk 2017-07-24 12:42 GMT+03:00 Gerd Hoffmann : > On Sun, 2017-07-23 at 22:44 +0300, Alexander Bezzubikov wrote: > > By the way, any ideas on how to avoid 'bus overstealing' would > > be greatly appreciated. > > Static BIOS variable isn't applicable since its value isn't saved > > across reboots. > > I think the reservation hints should be a absolute number, not a > increment. i.e. if qemu suggests to reserve three extra bus numbers > seabios should reserve three, no matter whenever there are zero, one, > two or three child busses present. And I guess seabios should > interpret that as minimum, so in case it finds five child busses it > will allocate five bus numbers of course ... > Personally I have nothing against it. Marcel, Michael, what do you think? > > Same with the other limit hints. If the hint says to allocate 16M, and > existing device bars sum up to 4M, allocate 16M (and therefore leave > 12M address space for hotplug). If the device bars sum up to 32M, > allocate that. > > While being at it: I have my doubts the capability struct layout > (which mimics register layout) buys us that much, seabios wouldn't > blindly copy over the values anyway. Having regular u32 fields looks > more useful to me. > > Again, if nobody has any objections, I can change it in v3. > cheers, > Gerd > > -- Alexander Bezzubikov