Re: possible UBSAN problems with xen drivers in kernel-6.5 in Noble (ub-24.04), please test a domU

[Pry Mar <pryorm09@xxxxxxxxx>]

There are 4 recent distros using the kernel-6.5, that might be used with Xen dom0/domU, I've attached a table with their

UBSAN status.

On Wed, Nov 8, 2023 at 8:53 PM Pry Mar <pryorm09@xxxxxxxxx> wrote:

Hello,

Looking for feedback from anyone running the latest devel ubuntu, 24.04. I did a domU install from debootstrap

and installed the default linux-image-virtual, 6.5.0-9.

I am getting a steady stream of UBSAN errors in dmesg from

  xen-netfront

  xen-blkfront

My dom0 is bookworm with xen-4.17.2.

I've reported this to #ubuntu-kernel on libera IRC and they don't believe that the kernel in Noble is any different than

the kernel in Jammy. They both have the same UBSAN kernel config. Somehow the xen drivers in 6.5.0-9 are behaving

very different, giving off far too many errors, although the domU works as normal.

I've requested they recompile with the UBSAN config turned off, which is what Debian does with kernel-6.5.0-x in bookworm-backports.

I suspect that once folks start installing the xen packages for dom0 the fan will blow a foul wind.

cheers,

PryMar56

Kernel 6.5 Xen Status in recent distro

distro	id	repo	pkg-name	version	compiler version	ubsan status	xen-status
debian	12	bookworm-backports	linux-image-amd64	6.5.3-1~bpo12+1	gcc-12.2	off	dom0/domU OK
elrepo	el9	elrepo-kernel	kernel-ml-core	6.5.10.el9	gcc-11.4	off	dom0/domU OK
ubuntu	24.04	main	linux-image-generic	6.5.0	gcc-13.2	on	dom0/domU polluted with errors
fedora	fc39	base	kernel-core	6.5.9	gcc-13.2	off	dom0/domU OK