Re: kern/57560: xennetback_xenbus.c rev 1.109 broke guests, causes DOM0 reboot

[Brad Spencer <brad%anduin.eldar.org@localhost>]

The following reply was made to PR port-xen/57560; it has been noted by GNATS.

From: Brad Spencer <brad%anduin.eldar.org@localhost>
To: Taylor R Campbell <riastradh%NetBSD.org@localhost>
Cc: gnats-bugs%NetBSD.org@localhost
Subject: Re: kern/57560: xennetback_xenbus.c rev 1.109 broke guests, causes
 DOM0 reboot
Date: Fri, 04 Aug 2023 06:48:27 -0400

 Taylor R Campbell <riastradh%NetBSD.org@localhost> writes:
 
 > Also, can you check to see if there's anything from the previous boot
 > in dmesg when the dom0 comes back?
 
 While I did not do that as a routine matter during the testing, I did
 check one time and there was nothing.  The dmesg started with the NetBSD
 kernel boot messages as far as I could tell.  Should the lockup / panic
 happen again I will look.
 
 >> Starting at 1.109, when ANY Xen guest starts to use its network
 >> interfaces, the DOM0 mentioned will lock up for a bit and reboot.
 >
 > How long is `for a bit'?  Around 15sec or something else?
 
 Less than 15 second, something in the range of 5 to 8 seconds I would
 guess.  I wasn't timing the hang very closely.  The DOM0 was fine up
 until the point that the DOMU started networking and at that point, ya,
 something like 5 to 8 seconds and then the DOM0 screen would blank, sync
 would drop on the VGAish monitor and a reboot would proceed.  No DDB, no
 DOM0 panic traceback messages, etc...  Sort of like one hit the hard
 reset button (at least without ACPI involved).
 
 
 
 
 -- 
 Brad Spencer - brad%anduin.eldar.org@localhost - KC8VKS - http://anduin.eldar.org