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Bug#983357: Netinst crashes xen domU when loading kernel



On 5/25/2021 2:38 PM, Phillip Susi wrote:
Michael Biebl writes:

So this is a change in behaviour in the kernel?
Yes, this commit fixed the kernel to report the error instead of
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>

What happens if you boot the installed system? Does udevadm trigger fail
there as well?
Yes, it does; that is how I was able to track down the problem.

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.
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


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