From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kevin O'Connor Subject: Re: [RFC PATCH v3 3/3] fw/pci: Allocate IGD stolen memory Date: Mon, 15 Feb 2016 09:15:09 -0500 Message-ID: <20160215141509.GA29746@morn.lan> References: <20160213001835.18456.46422.stgit@gimli.home> <20160213002318.18456.48603.stgit@gimli.home> <20160213024904.GA31040@morn.lan> <20160213081209.6e4342ab@t450s.home> <20160213181838.GA8842@morn.lan> <20160213115151.542d5d42@t450s.home> <20160213200509.GB16826@morn.lan> <20160213135709.692f9a55@t450s.home> <20160214002032.GA27805@morn.lan> <20160213180331.2aa0d010@t450s.home> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: seabios@seabios.org, allen.m.kay@intel.com, qemu-devel@nongnu.org, kvm@vger.kernel.org, "Michael S. Tsirkin" , Igor Mammedov To: Alex Williamson Return-path: Received: from mail-qg0-f65.google.com ([209.85.192.65]:33854 "EHLO mail-qg0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751714AbcBOOPL (ORCPT ); Mon, 15 Feb 2016 09:15:11 -0500 Received: by mail-qg0-f65.google.com with SMTP id e61so10627523qgf.1 for ; Mon, 15 Feb 2016 06:15:10 -0800 (PST) Content-Disposition: inline In-Reply-To: <20160213180331.2aa0d010@t450s.home> Sender: kvm-owner@vger.kernel.org List-ID: On Sat, Feb 13, 2016 at 06:03:31PM -0700, Alex Williamson wrote: > On Sat, 13 Feb 2016 19:20:32 -0500 > "Kevin O'Connor" wrote: > > This confuses me - why didn't the host system BIOS turn on the LCD > > panel during host bootup? > > It turns off when we reset the device between VM instances or between > VM boots. IGD supports Function Level Reset (FLR). > > > >Another desktop IvyBridge system > > > doesn't really care about the vBIOS so long as we don't ask it to > > > output anything before the guest native drivers are loaded. If we > > > could, I think we'd just enable vBIOS for laptop panel support, but > > > that's really not an option, it's going to run as a boot option ROM as > > > well, so we need to fix the issues that it generates there. > > > > From my experience with coreboot, running the vga option rom multiple > > times during a given boot is very fragile. (By multiple times, I mean > > either the host running it and then a guest, or running it multiple > > times from multiple guests.) YMMV. > > We do this regularly for graphics assignment, Nvidia, AMD, and now > Intel. It generally works ok. Perhaps you've seen issues with the > option ROM being run multiple times without resetting the device. I > could certainly believe that. Interesting. Using the FLR could be useful on some coreboot systems where users want to run the option rom twice. Thanks. -Kevin