From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39757) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bIVBg-0004Ei-6f for qemu-devel@nongnu.org; Thu, 30 Jun 2016 02:10:57 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bIVBa-00059G-Kn for qemu-devel@nongnu.org; Thu, 30 Jun 2016 02:10:55 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37927) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bIVBa-00057a-Ep for qemu-devel@nongnu.org; Thu, 30 Jun 2016 02:10:50 -0400 Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id DCF4E1054D for ; Thu, 30 Jun 2016 06:10:48 +0000 (UTC) Message-ID: <1467267046.15123.94.camel@redhat.com> From: Gerd Hoffmann Date: Thu, 30 Jun 2016 08:10:46 +0200 In-Reply-To: <20160629164252.GD10488@work-vm> References: <20160617151900.GE18662@thinpad.lan.raisama.net> <20160617154905.GH18662@thinpad.lan.raisama.net> <20160621194440.GN17952@thinpad.lan.raisama.net> <9b76415a-23e6-3ded-4dbc-42838cc164b0@redhat.com> <20160622142414.GI30202@redhat.com> <20160623014216-mutt-send-email-mst@redhat.com> <20160622232308.GQ30202@redhat.com> <20160623024400-mutt-send-email-mst@redhat.com> <1466671203.26189.35.camel@redhat.com> <20160629164252.GD10488@work-vm> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Mime-Version: 1.0 Subject: Re: [Qemu-devel] Default for phys-addr-bits? (was Re: [PATCH 4/5] x86: Allow physical address bits to be set) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Dr. David Alan Gilbert" Cc: "Michael S. Tsirkin" , Andrea Arcangeli , Marcel Apfelbaum , Paolo Bonzini , qemu-devel@nongnu.org, Eduardo Habkost Hi, > Something somewhere in qemu/ kernel/ firmware is already reading the numb= er > of physical bits to determine PCI mapping; if I do: >=20 > ./x86_64-softmmu/qemu-system-x86_64 -m 4096,slots=3D16,maxmem=3D128T No, it's not the physbits. You add some memory hotplug slots here. Qemu will ask seabios to reserve address space for those, which seabios promptly does and maps 64bit pci bars above the reserved address space. > -vga none -device qxl-vga,bus=3Dpcie.0,ram_size_mb=3D2048,vram64_size_= mb=3D2048 -vnc 0.0.0.0:0 /home/vms/7.2a.qcow2 -chardev stdio,mux=3Don,id=3D= mon -mon chardev=3Dmon,mode=3Dreadline -cpu host,phys-bits=3D48 >=20 > it will happily map the qxl VRAM right up high, but if I lower > the phys-bits down to 46 it won't. I suspect the linux kernel remaps the bar because the seabios mapping is unreachable. Check dmesg. cheers, Gerd