[Pkg-xen-devel] Bug#910946: Bug#910946: xen-hypervisor-4.11-amd64: HVM DomU - 64-bit kernel cannot access emulated ATA devices

[Hans van Kranenburg]

Hi Stephen,

On 10/13/2018 07:31 PM, Stephen Oberholtzer wrote:
> Package: xen-hypervisor-4.11-amd64
> Version: 4.11.1~pre.20180911.5acdd26fdc+dfsg-3
> Severity: normal

Thanks for trying out the new Xen 4.11 packages, spending time testing
things and writing up reports.

> Dear Maintainer,
> 
> This mostly manifests as an "unable to access emulated CD-ROM drive", because there are no PVHVM CD-ROMs.
> 
> NOTE: I had similar issues with 4.8, so I upgraded to 4.11. This actually gave me *more* issues.

Yeah, I've noticed that you also reported this earlier on #xen irc.

There was a reply from Andrew Cooper:
19:35 < andyhhp__> Stevie-O: Thats most likely a dom0 kernel bug
19:35 < andyhhp__> the 32 and 64bit block protocols were binarily
diverged for a while due to some "interesing" bugfixes
19:36 < andyhhp__> but its the most common cause of "32bit works, 64bit
doesn't" when it comes to anything vaguely like disks

I suspect that this issue, together with the other two issues you just
opened are not things that can easily be resolved only by the people
doing the packaging work for Debian. This means that we have to get into
the mode "let's prepare a well-written bug report for upstream xen
developers".

Since the comments from Andrew point at at least the dom0 kernel version
being a factor in this equation: can you also add linux kernel version
information for dom0 and domU for your tests? These kind of things
explode into a testing-matrix of combinations of things very fast, and
any testing you can do providing that info will help other people
helping you narrowing down the issue.

Thanks,

> Attempting to boot an HVM domU from a CD image (to perform an install or rescue on VM data) fails when the CD uses a 64-bit kernel.
> (When I use the Knoppix 'failsafe' mode, which uses a 32-bit kernel, I get different behavior.  Under 4.8, it boots; under 4.11, it hangs during ATA bus probing.)
> 
> I have tried the following ISO images:
> * debian-buster-DI-alpha3-amd64-netinst.iso (tested on 4.8 only; can't use at all on 4.11)
> * KNOPPIX_V8.2-2018-05-10-EN.iso
> * debian-live-9.5.0-amd64-kde.iso
> * gparted-live-0.32.0-1-amd64.iso
> 
> Here are some additional details (mostly gleaned from Knoppix, because that's what I was doing my testing with):
> - When I try booting Knoppix in a non-accelerated VM by directly running qemu, everything works fine, so Xen is definitely a factor.
> - PVHVM is working: non-CDROM drive shows up as xvbda
> - With PVHVM disabled (xen_platform_pci=0), hda also fails to be detected
> - Persuading libata to dump IDENTIFY data reveals that the returned page is all zeroes.
> 
> 
> -- System Information:
> Debian Release: buster/sid
>   APT prefers testing
>   APT policy: (900, 'testing'), (400, 'unstable')
> Architecture: amd64 (x86_64)
> 
> Kernel: Linux 4.18.6 (SMP w/12 CPU cores)
> Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US.UTF-8 (charmap=UTF-8)
> Shell: /bin/sh linked to /bin/dash
> Init: systemd (via /run/systemd/system)
> LSM: AppArmor: enabled
> 
> xen-hypervisor-4.11-amd64 depends on no packages.
> 
> Versions of packages xen-hypervisor-4.11-amd64 recommends:
> ii  xen-hypervisor-common  4.11.1~pre.20180911.5acdd26fdc+dfsg-1~exp1
> ii  xen-utils-4.11         4.11.1~pre.20180911.5acdd26fdc+dfsg-3
> 
> xen-hypervisor-4.11-amd64 suggests no packages.
> 
> -- no debconf information

--
Hans van Kranenburg