can you add your hw specs and also what about Debian-Stretch? J ----- On 12 Feb, 2017, at 18:05, Chuck Zmudzinski [email protected] wrote:
> This bug, at its core, is that currently there is no supported solution > for VGA > passthrough on Xen for stable version Jessie from Debian. > > After browsing Xen's repositories, I found out that Xen did not claim to > support > VGA passthrough with the upstream qemu-xen device model until Sep 25, > 2015, the > date the xl.cfg man page was updated to indicate support for VGA passthrough > with upstream qemu-xen. This change to the xl.cfg man page was only made > on the > Xen version 4.7 and 4.8 branches, so if you want to use VGA passthrough > without > the traditional qemu-dm binary, you must upgrade to at least Xen version > 4.7. > Debian testing (currently stretch) uses Xen 4.8 and it presumably > supports VGA > passthrough without qemu-xen-traditional but I have not tried it. > > This situation leaves users of Debian stable (currently Jessie) with no > supported solution from Debian for VGA passthrough on Xen. Obviously > there are > two solutions. Backport Xen 4.7 or greater to Jessie, or restore the > traditional qemu-dm binary to the Xen 4.4.x package for Jessie. > > A couple of months ago I decided to try and rebuild the Xen source package > for Jessie with support for qemu-xen-traditional from upstream included. > It did > not take long to get a working package that solves this bug. I > discovered the > following facts: > > 1. Adding qemu-xen-traditional in a way supported by Xen also requires > rombios > which, like qemu-xen-traditional, is disabled in Debian's official > build of > Xen for Jessie. > > 2. After configuring the build for qemu-xen-traditional and rombios, the > only > binary package that is modified significantly is xen-utils-4.4, which is > where the qemu-dm binary is installed, and where a modified > hvmloader binary > is installed so it includes the statically linked rombios modules. > > 3. With these changes to xen-utils-4.4, together with a few simple > configuration > tweaks such as the location of the qemu keymaps directory, VGA > passthrough > on Debian Jessie works with HVM domains that use qemu-xen-traditional, > and this feature can be enabled simply by adding 2 lines to the config > file: device_model_version = 'qemu-xen-traditional' > gfx_passthru = '1' > I think the second option is only needed if you want the passed through > video card to be the primary video adapter, but I have never tried VGA > passthrough as a secondary adapter in the HVM. Your mileage may vary. > > 4. Also, with these changes to xen-utils, the qemu-xen upstream device model > and the seabios bios remain the defaults, so these changes will not do > violence to existing installations that use upstream qemu-xen and > seabios. > > 5. It is not possible to build the Xen source package with > qemu-xen-traditional > in such a way that it meets all the requirements for inclusion in > the main > area of Debian's archive of packages. Specifically, the build must > access > remote repositories to download qemu-xen-traditional source files from > xen.org and ipxe source files from ipxe.org. Later I found it is > possible to > build and configure a working package that supports VGA passthrough > without > ipxe by making a couple of small configuration tweaks that remove > etherboot > and ipxe support from the rombios modules that are statically linked > into > hvmloader. But the requirement that the build not access the > internet for > source files cannot be met unless the xen source package is modified > by adding another original source tar archive, something like the > xen_4.1.6.lts1.orig-qemu.tar.xz source file for the xen package for > oldstable > Wheezy that does include support for qemu-xen-traditional and VGA > passthrough, in order for the build to succeed without needing to access > a remote repository. > > With these discoveries, I would like to make the observation that > although it is > not trivial, it seems like it would not be too dificult for the Debian > Xen team > to add support for qemu-xen-traditional and rombios to the Xen source > package so > the resulting binary packages would support VGA passthrough when an HVM > domain > is configured to use qemu-xen-traditional. > > After having said all this, the stage is set for my question: Why hasn't the > Debian Xen team added support for VGA passthrough in Debian Jessie? > > From Archived Bug #688311, Bastian Blank asserted that qemu-dm will not > come > back and that you have to use the normal (now called upstream) qemu. > > Ian Campbell responded: "Just FYI position of upstream is that the > 'traditional' > qemu-dm will continue to be maintained for the foreseeable future for the > benefit of users who are running guest OSes which are not as happy to > have the > "motherboard" changed from under them as Linux is." > > That was over four years ago, and Debian still has not restored qemu-dm so > users of a stable Debian system can have a working VGA Passthrough for any > guest OS, not even Linux, much less users of those Oses that don't like the > motherboard changed from other them. > > As far as I can tell, Xen still maintains the traditional qemu-dm, and I was > able to recently rebuild the xen package for Jessie and get VGA Passthrough > working on Jessie with the most recent version of the traditional device > model > that is available from Xen for the stable 4.4 release of Xen. > > So I ask again, why can't the Debian Xen team restore qemu-dm to its > official > Xen package for Jessie? > > The only reasonable reasons I can think of is that there is some free > software > licensing issue with the rombios modules that are statically linked to > hvmloader > or with some necessary component of qemu-dm, or the Debian Xen team has > too few > resources and is devoting its efforts to developing Xen for stretch > rather than > adding feaatures that did not make it into Jessie when it was released. > But why > should oldstable Wheezy have a feature that stable Jessie does not have? > > In any case, I hope the Debian Xen team can explain why qemu-dm cannot be > restored to Debian Jessie's offical xen package. > > Thank you for your consideration of my question. > > Sincerely, > > Chuck Zmudzinski
