From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Williamson Subject: Re: Graphics pass-through Date: Mon, 09 May 2011 08:29:31 -0600 Message-ID: <1304951371.26106.26.camel@x201> References: <4D415D70.8070105@web.de> <1296175554.2891.29.camel@x201> <4DC264CD.9080700@siemens.com> <1304608642.3081.35.camel@x201> <4DC7CCB3.8030607@siemens.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: =?ISO-8859-1?Q?Andr=E9?= Weidemann , Prasad Joshi , "kvm@vger.kernel.org" , Oswaldo Cadenas To: Jan Kiszka Return-path: Received: from mx1.redhat.com ([209.132.183.28]:41468 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751881Ab1EIO3f (ORCPT ); Mon, 9 May 2011 10:29:35 -0400 In-Reply-To: <4DC7CCB3.8030607@siemens.com> Sender: kvm-owner@vger.kernel.org List-ID: On Mon, 2011-05-09 at 13:14 +0200, Jan Kiszka wrote: > On 2011-05-05 17:17, Alex Williamson wrote: > >> And what about the host? When does Linux release the legacy range? > >> Always or only when a specific (!=vga/vesa) framebuffer driver is loaded? > > > > Well, that's where it'd be nice if the vga arbiter was actually in more > > widespread use. It currently seems to be nothing more than a shared > > mutex, but it would actually be useful if it included backends to do the > > chipset vga routing changes. I think when I was testing this, I was > > externally poking PCI bridge chipset to toggle the VGA_EN bit. > > Right, we had to drop the approach to pass through the secondary card > for now, the arbiter was not switching properly. Haven't checked yet if > VGA_EN was properly set, though the kernel code looks like it should > take care of this. > > Even with handing out the primary adapter, we had only mixed success so > far. The onboard adapter worked well (in VESA mode), but the NVIDIA is > not displaying early boot messages at all. Maybe a vgabios issue. > Windows was booting nevertheless - until we installed the NVIDIA > drivers. Than it ran into a blue screen. Interesting, IIRC I could never get VESA modes to work. I believe I only had a basic VGA16 mode running in a Windows guest too. > BTW, what ATI adapter did you use precisely, and what did work, what not? I have an old X550 (rv380?). I also have an Nvidia gs8400, but ISTR the ATI working better for me. > One thing I was wondering: Most modern adapters should be PCIe these > days. Our NVIDIA definitely is. But so far we are claiming to have it > attached to a PCI bus. That caps all the extended capabilities e.g. > Could this make some relevant difference? The BIOS and early boot use shouldn't care too much about that, but I could imagine the high performance drivers potentially failing. Thanks, Alex