Regression in 7.1-rc1 in booting Ubuntu distro kernel

[Steve French]

I was able to workaround the problem with current kernels by doing
(after installing today's kernel packages):

      update-initramfs -c -k 7.1.0-070100rc2daily20260508-generic
then
      update-grub


On Fri, May 8, 2026 at 10:50 AM Steve French <smfrench at gmail.com> wrote:
>
> I had not realized that initrd is generated not installed via the
> kernel package, so I generated the missing initrd file and rebooted
> but it still failed with the same error.  Ideas?
>
> The following command was what I used to generate the missing file:
>          update-initramfs -c -k 7.1.0-070100rc2daily20260507-generic
>
> Ideas how to get Ubuntu to boot with recent kernels?
>
> On Thu, May 7, 2026 at 8:58 PM Steve French <smfrench at gmail.com> wrote:
> >
> > It still is failing with today's Ubuntu mainline build but I don't
> > think it is related to the module package not being installed.  I see
> > dpkg showing e.g. "linux-modules-7.1.0-070100rc2daily20260507-generic"
> > installed, and I also see
> > "linux-image-unsigned-7.1.0-070100rc2daily20260507-generic" installed
> >
> > But I am suspicious that the packages are simply missing the initrd
> > file.  I don't see any initrd fails for 7.1-rc1 or later:
> >
> > /boot# ls initrd* -lot | more
> > lrwxrwxrwx 1 root        47 May  7 17:14 initrd.img ->
> > initrd.img-7.1.0-070100rc2daily20260507-
> > generic
> > lrwxrwxrwx 1 root        28 May  7 17:14 initrd.img.old ->
> > initrd.img-6.17.0-23-generic
> > -rw-r--r-- 1 root  87410754 May  6 06:41 initrd.img-6.17.0-23-generic
> > -rw-r--r-- 1 root  88310841 May  1 08:26 initrd.img-7.0.0-070000rc5-generic
> > -rw-r--r-- 1 root  88290147 Apr 26 20:15
> > initrd.img-7.0.0-070000daily20260426-generic
> > -rw-r--r-- 1 root  88327325 Apr 18 20:10 initrd.img-7.0.0-070000-generic
> >
> > The most recent initrd I see that works is the one from the day before
> > 7.1-rc1 ("initrd.img-7.0.0-070000daily20260426-generic") but I don't
> > see any of the 7.1 initrd files which looks like a packaging bug in
> > the Ubuntu mainline kernel since the corresponding linux-image package
> > is installed.
> >
> > When I manually extract all of the files from the image .deb:
> >
> >     dpkg-deb -x
> > linux-image-unsigned-7.1.0-070100rc2daily20260507-generic /tmppkg/
> >
> > I only see /boot/vmlinuz not /boot/initrd so it looks like the package
> > is missing file(s)
> >
> > root at smfrench-ThinkPad-P16s-Gen-2:/tmppkg/boot# ls
> > vmlinuz-7.1.0-070100rc2daily20260507-generic
> >
> > Any ideas how to get current Ubuntu to boot with recent mainline?
> >
> > On Wed, May 6, 2026 at 2:57 AM Aaron Ma <aaron.ma at canonical.com> wrote:
> > >
> > > Hi Steve,
> > >
> > > This error is indicated that rootfs is not loaded, please check if the
> > > kernel module package is installed and initramfs is made for the new
> > > kernel.
> > >
> > > Regards,
> > > Aaron
> > >
> > > On Wed, May 6, 2026 at 2:16 PM Steve French <smfrench at gmail.com> wrote:
> > > >
> > > > I notice failures in booting Ubuntu 25.10 on my Lenovo Thinkpad laptop
> > > > since 7.1-rc1 kernel.  I have not seen this error before.
> > > >
> > > > "KERNEL PANIC! Please reboot your computer.  VFS: Unable to mount root
> > > > fs on unknown-block(0,0)"
> > > >
> > > > which doesn't make any sense because that isn't the root fs.  /etc/fstab shows:
> > > >
> > > > /dev/disk/by-uuid/6ca90829-120e-4d09-be02-46422daffdcd / ext4 defaults 0 1
> > > >
> > > >
> > > > The last kernel that booted successfully was the daily build from the
> > > > day before (4/26/26
> > > > https://kernel.ubuntu.com/mainline/daily/2026-04-26/).  It also fails
> > > > on current daily builds and on 7.1-rc2 kernel
> > > > (https://kernel.ubuntu.com/mainline/v7.1-rc2/) so I have been stuck
> > > > doing my testing on out of tree builds booting from a few weeks old
> > > > kernel.
> > > >
> > > > Any ideas how to find out what regressed in the mainline kernel in
> > > > 7.1-rc1 (or in the ubuntu mainline daily build) or how to workaround
> > > > or debug this?
> > > > --
> > > > Thanks,
> > > >
> > > > Steve
> > > >
> > > > --
> > > > kernel-team mailing list
> > > > kernel-team at lists.ubuntu.com
> > > > https://lists.ubuntu.com/mailman/listinfo/kernel-team
> >
> >
> >
> > --
> > Thanks,
> >
> > Steve
>
>
>
> --
> Thanks,
>
> Steve



-- 
Thanks,

Steve