Every bullseye netinst image I have tried to boot in a xen domU has
crashed and rebooted the domU after choosing any entry from the boot
menu.  I thought there might have been something wrong with my xen
server, which was running Ubuntu 18.04, but I rebuilt it the other day
using bullseye as the dom0, and I still can't install bullseye in a
domU.

reassign 983357 linux
severity grave
thanks

I rebuilt the iso using the version of isolinux from stable and it still
crashed the domU.  When I rebuilt it using the vmlinux and initrd.gz
from the stable iso, it successfully boots, so it appears to be caused
by the kernel.

Interestingly, there appears to be a different kernel build just for use
under xen in install.amd/xen and using that one also works.  Maybe we
need a menu option in isolinux to load that kernel instead?

The netinst image I had contained the -3 kernel.  I rebuit the image
with the current -6 kernel and it worked.  I downloaded the latest
weekly netinst iso and it already contains the -6 kernel, so it appears
that this has been fixed in -4, -5, or -6.

reopen 983357
thanks

I don't know what happened, but it is back to not working, even with the
install.amd/xen/ kernel.

Phillip Susi writes:

affects 983357 + debian-installer
severify 983357 serious
thanks

It appears that the root cause of this bug has been reported upstream
here:

https://bugzilla.kernel.org/show_bug.cgi?id=207695

It seems that there is an error trying to udev trigger the Xen virtual
keyboard, and this causes start-udev to bail out, which causes init to
bail out and the kernel to panic.  Removing the set -e from start-udev
appears to be a viable workaround that d-i might want to consider.

I bisected the problem to this commit:

commit df44b479654f62b478c18ee4d8bc4e9f897a9844
Author: Peter Rajnoha <prajnoha@redhat.com>
Date:   Wed Dec 5 12:27:44 2018 +0100

    kobject: return error code if writing /sys/.../uevent fails

    Propagate error code back to userspace if writing the /sys/.../uevent
    file fails. Before, the write operation always returned with success,
    even if we failed to recognize the input string or if we failed to
    generate the uevent itself.

    With the error codes properly propagated back to userspace, we are
    able to react in userspace accordingly by not assuming and awaiting
    a uevent that is not delivered.

    Signed-off-by: Peter Rajnoha <prajnoha@redhat.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

So it appears that the Xen Virtual Keyboard driver was always broken but
the error in triggering the uevent was not previously reported.  The
upstream bug report notes another driver failing.  There are probably
other drivers too.

I will continue to try to find and fix the Xen keyboard error so it no
longer fails anyway, but it is probably a good idea to patch the
start-udev script in d-i to ignore errors.  It is better to continue
with some device not triggering a cold plug event than to instantly panic
the kernel in early boot.

I dug down to the the -ENOMEM coming from the fact that the modalias is
over 2KB of crap so it won't fit in the environment block when the input
core tries to add it for the uevent.  I don't see how it gets this way
though because the MODULE_ALIAS() statement in the code just says it
should be "xen: vkbd".

When I read the modalias in sysfs, it says:

input:b0001v5853pFFFFe0000-e0,1,k71,72,73,74,75,76,77,78,79,7A,7B,7C,7D,\
7E,7F,80,81,82,83,84,85,86,87,88,89,8A,8B,8C,8D,8E,8F,90,91,92,93,94,95,\
96,97,98,99,9A,9B,9C,9D,9E,9F,A0,A1,A2,A3,A4,A5,A6,A7,A8,A9,AA,AB,AC,AD,\
AE,AF,B0,B1,B2,B3,B4,B5,B6,B7,B8,B9,BA,BB,BC,BD,BE,BF,C0,C1,C2,C3,C4,C5,\
C6,C7,C8,C9,CA,CB,CC,CD,CE,CF,D0,D1,D2,D3,D4,D5,D6,D7,D8,D9,DA,DB,DC,DD,\
DE,DF,E0,E1,E2,E3,E4,E5,E6,E7,E8,E9,EA,EB,EC,ED,EE,EF,160,161,162,163,16\
4,165,166,167,168,169,16A,16B,16C,16D,16E,16F,170,171,172,173,174,175,17\
6,177,178,179,17A,17B,17C,17D,17E,17F,180,181,182,183,184,185,186,187,18\
8,189,18A,18B,18C,18D,18E,18F,190,191,192,193,194,195,196,197,198,199,19\
A,19B,19C,19D,19E,19F,1A0,1A1,1A2,1A3,1A4,1A5,1A6,1A7,1A8,1A9,1AA,1AB,1A\
C,1AD,1AE,1AF,1B0,1B1,1B2,1B3,1B4,1B5,1B6,1B7,1B8,1B9,1BA,1BB,1BC,1BD,1B\
E,1BF,1C0,1C1,1C2,1C3,1C4,1C5,1C6,1C7,1C8,1C9,1CA,1CB,1CC,1CD,1CE,1CF,1D\
0,1D1,1D2,1D3,1D4,1D5,1D6,1D7,1D8,1D9,1DA,1DB,1DC,1DD,1DE,1DF,1E0,1E1,1E\
2,1E3,1E4,1E5,1E6,1E7,1E8,1E9,1EA,1EB,1EC,1ED,1EE,1EF,1F0,1F1,1F2,1F3,1F\
4,1F5,1F6,1F7,1F8,1F9,1FA,1FB,1FC,1FD,1FE,1FF,200,201,202,203,204,205,20\
6,207,208,209,20A,20B,20C,20D,20E,20F,210,211,212,213,214,215,216,217,21\
8,219,21A,21B,21C,21D,21E,21F,220,221,222,223,224,225,226,227,228,229,22\
A,22B,22C,22D,22E,22F,230,231,232,233,234,235,236,237,238,239,23A,23B,23\
C,23D,23E,23F,240,241,242,243,244,245,246,247,248,249,24A,24B,24C,24D,24\
E,24F,250,251,252,253,254,255,256,257,258,259,25A,25B,25C,25D,25E,25F,26\
0,261,262,263,264,265,266,267,268,269,26A,26B,26C,26D,26E,26F,270,271,27\
2,273,274,275,276,277,278,279,27A,27B,27C,27D,27E,27F,280,281,282,283,28\
4,285,286,287,288,289,28A,28B,28C,28D,28E,28F,290,291,292,293,294,295,29\
6,297,298,299,29A,29B,29C,29D,29E,29F,2A0,2A1,2A2,2A3,2A4,2A5,2A6,2A7,2A\
8,2A9,2AA,2AB,2AC,2AD,2AE,2AF,2B0,2B1,2B2,2B3,2B4,2B5,2B6,2B7,2B8,2B9,2B\
A,2BB,2BC,2BD,2BE,2BF,2C0,2C1,2C2,2C3,2C4,2C5,2C6,2C7,2C8,2C9,2CA,2CB,2C\
C,2CD,2CE,2CF,2D0,2D1,2D2,2D3,2D4,2D5,2D6,2D7,2D8,2D9,2DA,2DB,2DC,2DD,2D\
E,2DF,2E0,2E1,2E2,2E3,2E4,2E5,2E6,2E7,2E8,2E9,2EA,2EB,2EC,2ED,2EE,2EF,2F\
0,2F1,2F2,2F3,2F4,2F5,2F6,2F7,2F8,2F9,2FA,2FB,2FC,2FD,2FE,ramlsfw

The discussion upstream does not seem to be converging on a proper fix
in the kernel, so I'm going to clone this bug and suggest that
debian-installer patch the start-udev script to ignore the failure of
the udevadm trigger command.

To summarize: init ends up calling start-udev which calls udevadm
trigger to cold plug all devices.  Both scripts are set -e.  The Xen
Virtual Keyboard driver and at least one other driver have always failed
to trigger due to having absurdly long modalias, but the error used to
be ignored.  The kernel now returns the error to udevadm, so it exits
with an error, so start-udev exits with an error, so init exits with an
error, causing the kernel to panic.

Hi Phillip,

And thanks for debugging this… I must confess I've never touched
anything Xen related and I'd like to keep it that way in the near
future. ;-)

Phillip Susi <phill@thesusis.net> (2021-05-19):

Well, it's a little more complicated:
 - start-udev is actually a script shipped by the udev udeb, i.e. the
   responsibility of systemd maintainers;
 - based on a quick grep, the installer contains two calls to that
   start-udev script, in the rootskel source package:
    + rootskel/src/init            (shipped as /init in the udeb)
    + rootskel/src/sbin/init-linux (shipped as /sbin/init in the udeb)

I'd be happy to have a comment from systemd maintainers before thinking
about patching rootskel. :)


Cheers,

Hi Phillip

Am 24.05.2021 um 06:19 schrieb Cyril Brulebois:

So this is a change in behaviour in the kernel?
What happens if you boot the installed system? Does udevadm trigger fail
there as well?

I feel a bit uneasy changing the udev start script this late in the
release cycle (especially when it appears like covering up an issue
someplace else).

I'll let Marco make the judgement on this though, as he has the most
experience with those udev udeb start scripts as the original author.

Michael

Michael Biebl writes:
silently failing:

commit df44b479654f62b478c18ee4d8bc4e9f897a9844
Author: Peter Rajnoha <prajnoha@redhat.com>
Date:   Wed Dec 5 12:27:44 2018 +0100

    kobject: return error code if writing /sys/.../uevent fails

    Propagate error code back to userspace if writing the /sys/.../uevent
    file fails. Before, the write operation always returned with success,
    even if we failed to recognize the input string or if we failed to
    generate the uevent itself.

    With the error codes properly propagated back to userspace, we are
    able to react in userspace accordingly by not assuming and awaiting
    a uevent that is not delivered.

    Signed-off-by: Peter Rajnoha <prajnoha@redhat.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Yes, it does; that is how I was able to track down the problem.

So far I have been removing the -e from the shbang line in the
start-udev script and remastering the iso so I can get it to boot.  It
would probably be a better idea to just add a || true to the udevadm
trigger call.  I feel fairly certain that no matter what the cause of
the coldplug failure, the user is going to be better off ignoring it and
trying to proceed than a kernel panic.

Hello,

This bug was noticed on the debian-user list recently and I have
been testing various workarounds and instead of removing -e from
the shbang line I came up with prepending the udevadm trigger call
in the start-udev script with

dmesg | grep DMI: | grep 'Xen HVM domU' ||

This causes the offending udevadm trigger call to never be invoked
when running in a Xen HVM DomU. On all other systems, the call
should be invoked like normal. With this hack, I was able to create
a modified ISO and run the bullseye installer from it in a Xen HVM
DomU and complete an install without the crash and reboot.

I also can confirm that I always see the coldplug failure on the installed
system in a Xen HVM DomU, but in that case the failure does not
cause a crash and the system boots normally after reporting the failure.

I also do not see the problem in a Xen PV DomU, which I think is
what the /install.amd/xen folder on the installation media is for.

Chuck Zmudzinski

After reviewing Philip's message at

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=983357#43

which seems to point to the root cause of this bug, I can add:

On my Xen HVM DomU I see the absurdly long modalias for the Xen
Virtual keyboard that seems to be causing this crash in sysfs at

/sys/devices/virtual/input/input2/modalias

But at /sys/devices/vkbd-0/modalias, I see just 'xen:vkbd', which would
probably not result in an error in the udev script if this was also
written as the modalias at /sys/devices/virtual/input/input2/modalias

So the Xen virtual keyboard appears more than once in sysfs, and
modalias is not the same in the different places. This seems
to be a problem.

I understand the correct way to fix this bug is by modifying the
Xxen virtual keyboard (and any other devices that might cause
this crash) and not the start-udev script on the netinst
installation media, which is so far the only available workaround.
Hopefully Xen will accept a fix if we can come up with a fix.

I am willing to try to debug this by testing patches to the Xen
virtual keyboard, and anyone who has any tips on how
udev works would be helpful. Is there documentation in udev for
device developers somewhere to consult that explains how to
update old device drivers so they are compatible with the
modern version? Does the Xen virtual keyboard need to be
managed by udev? Is there a simple way to disable incompatible
devices so udev ignores them?

Chuck Zmudzinski

They are two different devices, and they should have different
modaliases.

Linux has code for discovering devices on each kind of bus, including
virtual buses, and that code creates "bus devices" such as vkbd-0.  At
this point the kernel doesn't know what the device is capable of.  The
modalias for a bus device carries some identifying information that can
be used to select a driver module for it.

The driver does know what the device is capable of, and how to use it.
It will normally create one or more "class devices" that support a
particular set of operations; in this case input device operations.
Class devices typically don't have modaliases, since they don't need
another layer of drivers on top.  However, for input devices the
modalias carries information about the device's capabilities.  These
may trigger loading of the evdev or joydev module.
[...]

I think a proper fix would be one of:

a. If the Xen virtual keyboard driver is advertising capabilities it
   doesn't have, stop it doing that.
b. Change the implementation of modalias attributes to allow longer
   values.

It's not clear to me whether the Xen driver is advertising correctly or
not.  If it is, then the solution should be b, but that may be too
disruptive a change to the kernel.  So a reasonable workaround might
be:

c. Change the input subsystem to limit the length of the
   capabilities part of the modalias.


Ben.

So workaround c would not involve disruptions to the kernel or
systemd? Workaround c seems too disruptive for stable to me,
but maybe could go into unstable and eventually into testing.

A problem with the approach of fixing this bug in the Xen
keyboard driver is that the fix must be implemented in the underlying
Dom0 system, which could be almost anything - another Linux distro
or Debian stable or oldstable. Any fix upstream would probably get into
a bullseye Dom0, but not oldstable Dom0, but perhaps it could be
provided as a backport for anyone who is still on oldstable for their
Xen Dom0.

Anyway, I will look into the Xen virtual keyboard capabilities. The
only capability I can think of that would be useful in this context is that
it supports live migration of a VM through some sort of hot-swapping
capability. If it has that capability, a workaround to support it would be
good. But if it does not have that capability or if such a capability is
not needed for a keyboard, then it should probably stop advertising
itself as being able or needing to do that. Ultimately, it is up to Xen to
decide if they are going to make changes to its virtual keyboard.

Chuck

Ben Hutchings <ben@decadent.org.uk> writes:
and so it has no way of knowing what keys it actually has.  It is a fake
input device designed to pass through whatever input the Xen hypervisor
sends down.  As such, any key could come in.  If it doesn't advertise
that it has all of these keys, then they would not be accepted by
libinput when the hypervisor sends them down.

This seems to be the heart of the problem: libinput was designed
assuming that all keyboards can and must report what keys are actually
present, and then libinput tries to cram that information into the
modalias rather than some other sysfs attribute as it should ( or not at
all... I still don't see how this information is actually supposed to be
useful to userspace ).

As for b), the problem isn't with the modalias attribute itself, but
when the kernel tries to copy it into the environment block for the udev
callout.  The environment block is only a single page, and so limited to
4 KB.  And that's for everything else that goes into the environment,
not just the modalias.

Right, that's what I feared.

xen-kbdfront is setting the bits for keys in the ranges [KEY_ESC,
KEY_UNKNOWN) and [KEY_OK, KEY_MAX), which I think works out to 654
keys and 2362 bytes in the modalias.

I think modaliases aren't intended to be interpreted by user-space,
other than processing wildcards when matching to modules.

For input devices, the same information is available through other
variables in the uevent, in a more compact form.  The information *is*
useful for user-space; e.g. in initramfs-tools we recognise keyboard
devices and add their drivers to the initramfs but ignore other input
devices.

Text-based sysfs attributes are limited to a page, but udev receives
uevents through netlink, not sysfs.

The current limit on the environment of a uevent appears to be 2 KB
(UEVENT_BUFFER_SIZE defined in <linux/kobject.h>).  That seems like it
*might* be easier to change, so long as user-space doesn't have a
similar limit.

I looked into systemd/udev, and it seems to use an 8 KB buffer for
receiving uevents:

https://sources.debian.org/src/systemd/247.9-1/src/libsystemd/sd-device/device-monitor.c/?hl=390#L390

But as a first step I think increasing the kernel buffer size to 4 KB
would be enough.  Perhaps someone could test whether this patch to the
domU kernel makes udev happier:

--- a/include/linux/kobject.h
+++ b/include/linux/kobject.h
@@ -30,7 +30,7 @@

 #define UEVENT_HELPER_PATH_LEN		256
 #define UEVENT_NUM_ENVP			64	/* number of env pointers */
-#define UEVENT_BUFFER_SIZE		2048	/* buffer for the variables */
+#define UEVENT_BUFFER_SIZE		4096	/* buffer for the variables */

 #ifdef CONFIG_UEVENT_HELPER
 /* path to the userspace helper executed on an event */
--- END ---

?

Ben.

[...]

I don't think it would be very disruptive.  It might require a kernel
ABI bump, but we do those regularly during a stable release.  And this
bug is severe enough that I think a fix would be suitable for Debian
stable.
[...]

I agree that we need to fix this for domU independently of any protocol
change to allow discovery of which keys the underlying input device
has.  So we can't solve this with approach a.


Ben.

I will try it in my bullseye Xen HVM DomU.

I am not sure how to rebuild the installation media with a patched
systemd, but I can patch my installed Xen HVM DomU system
with a patched systemd with the increased buffer size and see if the
Coldplug failure early in the boot process goes away. If so, then it
is likely this patch to systemd would also fix the installation media.

If it doesn't work, I am also willing to try approach a by patching
the Linux kernel xen-kbdfront driver by removing the for loops that
advertise those 654 keys. I tend to agree with Philip that this is
totally unnecessary, but I suppose I could be wrong about that.
I read the discussion Philip had with the Xen developers and they
seemed to want to keep the Xen keyboard driver as it is.

Chuck

On Wed, 2021-08-25 at 12:45 -0400, Chuck Zmudzinski wrote:
[...]
[...]

Sorry for not being clear - this is a patch for the kernel.
Instructions for rebuilding the kernel package are at
<https://kernel-team.pages.debian.net/kernel-handbook/ch-common-tasks.html#s-common-official>.

I agree that you should check whether this fixes the coldplug error
before we try rebuilding the installer.

Ben.

The build failed with an error. I used the test-patches script to start
the build:

chuckz@debian:~/linuxdata/sources-bullseye/kernel/linux-5.10.46$ bash
debian/bin/test-patches ../patch

with Ben's patch to UEVENT_BUFFER_SIZE in ../patch.

The build was running for over an hour and then failed with the last few
lines on
the console as:

RT_SYMBOL
zl10039_attach���������������������������������� module:
drivers/media/dvb-frontends/zl10039, version: 0xc2effb6f -> 0x603a565b,
export: EXPORT_SYMBOL
zl10353_attach���������������������������������� module:
drivers/media/dvb-frontends/zl10353, version: 0x1faf92c1 -> 0x0baa0cfe,
export: EXPORT_SYMBOL
zpa2326_isreg_precious�������������������������� ignored, module:
drivers/iio/pressure/zpa2326, version: 0xc887d5f5 -> 0xed2234b3, export:
EXPORT_SYMBOL_GPL
zpa2326_isreg_readable�������������������������� ignored, module:
drivers/iio/pressure/zpa2326, version: 0x55c1d540 -> 0x70643406, export:
EXPORT_SYMBOL_GPL
zpa2326_isreg_writeable������������������������� ignored, module:
drivers/iio/pressure/zpa2326, version: 0x0d49987b -> 0x28ec793d, export:
EXPORT_SYMBOL_GPL
zpa2326_pm_ops���������������������������������� ignored, module:
drivers/iio/pressure/zpa2326, version: 0xf9a2894f -> 0x709ae67b, export:
EXPORT_SYMBOL_GPL
zpa2326_probe����������������������������������� ignored, module:
drivers/iio/pressure/zpa2326, version: 0x76b08b58 -> 0xeb45a43b, export:
EXPORT_SYMBOL_GPL
zpa2326_remove���������������������������������� ignored, module:
drivers/iio/pressure/zpa2326, version: 0xdb120e61 -> 0x1121e8d3, export:
EXPORT_SYMBOL_GPL
zpool_register_driver��������������������������� module: vmlinux,
version: 0x2caae392 -> 0x4e86309a, export: EXPORT_SYMBOL
zpool_unregister_driver������������������������� module: vmlinux,
version: 0x29f4da85 -> 0x4bd8098d, export: EXPORT_SYMBOL
make[1]: *** [debian/rules.real:214:
debian/stamps/build_amd64_none_amd64] Error 1
make[1]: Leaving directory
'/home/chuckz/linuxdata/sources-bullseye/kernel/linux-5.10.46'
make: *** [debian/rules.gen:27: binary-arch_amd64_none_amd64_real] Error 2

I think I have all the prerequisites, and I could not find a build log
to find
a more specific error. I know debuild creates a buildlog in the ..
folder when
building packages, but the test-patches script didn't do that.

Chuck

Chuck Zmudzinski <brchuckz@netscape.net> writes:

That was the first thing I tried and the libinput maintainer pointed out
that if you don't advertise the keys, you can't use the keys.  In other
words, somebody presses that key on their keyboard and the domU won't
recognize it.

I tried this patch but the build failed - it ran for over an hour. I am not
sure why as I have not built a Linux kernel in many years. So I will
this:

1) Try to build the unmodified kernel on my system just to be sure I
am building the kernel correctly and that my hardware is OK. Once
I could not build the Linux kernel until I replaced a bad memory
card.

2) If that succeeds, I will try the patch with a bump to the abi version.

 From the output of the failed build and what I read in the section on
the Debian kernel ABI name, I think that the system detected an
ABI change and so it failed. The build was checking symbols when
it failed.

This will take a little while because it takes over an hour to build the
kernel on my system.

Chuck

Well, good news - It looks like Ben's patch works, I just tested it in
my full
install in a Xen HVM domU and all looks good. I did not see the Coldplug
failure at the beginning of the boot - it is hard to miss in the bright red
letters on the console, and even more convincing is the fact that another
symptom of the bug is gone. This bug manifests itself in udev not being
able to write uevent data to sysfs for the Xen Virtual Keyboard. With
Ben's patch of increasing the UEVENT_BUFFER_SIZE from 2048 to 4096,
udev can write its uevent data to sysfs for the Xen Virtual Keyboard:

With the current 5.10.0-8 kernel:

chuckz@debian:~$ cat /sys/devices/virtual/input/input2/uevent
chuckz@debian:~$

With the patched kernel with a change to the ABI version from 8 to 8.1:

chuckz@debian:~$ uname -r
5.10.0-8.1-amd64
chuckz@debian:~$ cat /sys/devices/virtual/input/input2/uevent
PRODUCT=1/5853/ffff/0
NAME="Xen Virtual Keyboard"
PHYS="xenbus/device/vkbd/0"
PROP=0
EV=3
KEY=7fffffffffffffff ffffffffffffffff ffffffffffffffff...
MODALIAS=input:b0001v5853pFFFFe0000-e0,1,k71,72... really long MODALIAS

I expect with that patch the installation media will work
in a Xen HVM domU.

Cheers,

Chuck

I tested this patch on my Xen HVM bullseye system and
it appears 4k is enough for the UEVENT_BUFFER_SIZE
to accommodate the Xen Virtual Keyboard's large
modalias. I needed to follow the instructions in
the Kernel team's handbook for changing the ABI
name of the kernel for the build to succeed with
the patch. I just bumped it from 8 to 8.1.

Results:

1. No coldplug failure reported at boot time.

2. With the patch the system can write uevent
data to sysfs for the Xen Virtual Keyboard device.

With the current 5.10.0-8 kernel:

chuckz@debian:~$ cat /sys/devices/virtual/input/input2/uevent
chuckz@debian:~$

With the patched kernel with a change to the ABI version from 8 to 8.1:

chuckz@debian:~$ uname -r
5.10.0-8.1-amd64
chuckz@debian:~$ cat /sys/devices/virtual/input/input2/uevent
PRODUCT=1/5853/ffff/0
NAME="Xen Virtual Keyboard"
PHYS="xenbus/device/vkbd/0"
PROP=0
EV=3
KEY=7fffffffffffffff ffffffffffffffff ffffffffffffffff...
MODALIAS=input:b0001v5853pFFFFe0000-e0,1,k71,72... really long MODALIAS
---------------------------------------------------------------------------

So I think a test of the installation media in a Xen HVM with the
4k buffer in the kernel is the next step.

I would also like to test a live CD in a Xen HVM with this patch.
It was also reported to fail to boot in a Xen HVM on the
debian-user list.

BTW, my complements to the Debian Kernel Team for the
excellent handbook on building kernels for Debian. It is
easy to understand and made it very easy for me to
build and test the patch even though I have not built
a Linux kernel in many years, and I never built a Debian
kernel before.

All the best,

Chuck

Results of more tests with the patched kernel:

1. Boot on dom0 - works normally, can create VMs, run Liinux container, etc.
2. Boot in Xen PV - works normally
3. Boot on bare hardware - works normally

I do not see any issues with the patched kernel on my system.

Cheers,

Chuck

Even though this patch has been tested to apparently fix this bug and
the bug has been elevated to important and tagged patch and upstream,
AFAICT there is no action yet upstream or anywhere else after more than
three weeks. Is this patch dead as a possible fix for this bug?

Best wishes,

Chuck