Re: 5.18 vmwgfx seems to break booting VirtualBox VMs

[Zack Rusin <zackr@vmware.com>]

On Tue, 2022-05-10 at 14:44 +0200, Thorsten Leemhuis wrote:
> On 10.05.22 14:26, Zack Rusin wrote:
> > > On May 10, 2022, at 7:06 AM, Thorsten Leemhuis
> > > <regressions@leemhuis.info> wrote:
> > > On 10.05.22 02:12, Zack Rusin wrote:
> > > > > On May 9, 2022, at 6:57 AM, Hans de Goede
> > > > > <hdegoede@redhat.com>
> > > > > wrote: On 4/11/22 16:24, Zack Rusin wrote:
> > > > > > On Mon, 2022-04-11 at 10:52 +0200, Hans de Goede wrote:
> > > > > > > 
> > > > > > > Fedora has received a bug report here:
> > > > > > > 
> > > > > > > https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugzilla.redhat.com%2Fshow_bug.cgi%3Fid%3D2072556&amp;data=05%7C01%7Czackr%40vmware.com%7Cb9226bb1368e4f33671a08da3282c85d%7Cb39138ca3cee4b4aa4d6cd83d9dd62f0%7C0%7C0%7C637877834559681630%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=uqLgrc3fYw93qu1Gwdvc1YhCsFjejAy%2B4B%2BSgKzLil0%3D&amp;reserved=0
> > > > > > > 
> > > > > > > 
> > > > > > > 
> > > That Fedora rawhide VMs no longer boot under the VirtualBox
> > > > > > > hypervisor after the VM has been updated to a 5.18-rc#
> > > > > > > kernel.
> > > > > > > 
> > > > > > > Switching the emulated GPU from vmwaregfx to
> > > > > > > VirtualBoxSVGA
> > > > > > > fixes this, so this seems to be a vmwgfx driver
> > > > > > > regression.
> > > > > > > 
> > > > > > > Note I've not investigated/reproduced this myself due to
> > > > > > > -ENOTIME.
> > > > > > 
> > > > > > Thanks for letting us know. Unfortunately we do not support
> > > > > > vmwgfx on VirtualBox. I'd be happy to review patches
> > > > > > related to
> > > > > > this, but it's very unlikely we'd have to time to look at
> > > > > > this
> > > > > > ourselves.
> > > > > 
> > > > > I somewhat understand where you are coming from, but this is
> > > > > not 
> > > > > how the kernels "no regressions" policy works.
> > > 
> > > Hans, many thx for writing your mail, I once intended to write
> > > something
> > > similar, but then forgot about it. :-/
> > > 
> > > > > For the end user a regression is a regression and as
> > > > > maintainers we
> > > > > are supposed to make sure any regressions noticed are fixed
> > > > > before
> > > > > a new kernel hits end user's systems.
> > > > 
> > > > I think there’s a misunderstanding here - the vmwgfx driver
> > > > never
> > > > supported VirtualBox. VirtualBox implementation of the svga
> > > > device
> > > > lacks a bunch of features,
> > > 
> > > Which from the kernel's point of view is irrelevant. If the Linux
> > > kernel's vmwgfx driver ever supported the VirtualBox
> > > implementation then
> > > things shouldn't regress with later versions.
> > It never did. vmwgfx is just a driver for VMware's SVGA device, it
> > never supported anything else. 
> 
> Now I'm curious and would like to understand the issue properly, if
> you
> have a minute. :-D
> 
> I didn't mean "supported" as in "officially supported", I meant as in
> "it ran (as in automatically bonded) on VirtualBox in one of the
> modes
> one could configure in VirtualBox for virtual GPU". And the latter is
> the case here afaics, or isn't it?

I wouldn't know that. But if the claim is that anyone lying about the
type of device they are can hijack development then we'll need Linus to
clarify that, i.e. if I create a PCI device that identifies itself as a
random AMD GPU and crashes as soon you try to do any register access is
AMD gpu driver development done now? Clearly addition of any AMD gpu
driver would regress my device.

z