Bug#872999: qemu image built by vmdebootstrap is unbootable due to bad root=/dev/mapper/loop0p1 kernel parameter

[Raphael Hertzog]

On Thu, 07 Sep 2017, Ben Hutchings wrote:
> On Thu, 2017-09-07 at 12:53 +0200, Raphael Hertzog wrote:
> > On Thu, 07 Sep 2017, Raphael Hertzog wrote:
> > > What informs udev about the new filesystem?
> > 
> > Somehow, it's the kernel apparently.
> > 
> > > Or is this a bug in the kernel really?
> > 
> > At least "udevadm monitor" shows that the kernel is sending
> > less uevents when I run the command in the chroot.
> 
> Which command?

vmdebootstrap (for example as called by "make sid.raw" in that directory):
https://anonscm.debian.org/cgit/cloud/debian-vm-templates.git/tree/vmdebootstrap-generic-qcow2

The command creates the disk image with commands similar to those shown in this log:
2017-09-07 16:11:54 DEBUG runcmd: ['qemu-img', 'create', '-f', 'raw', '/srv/autopkgtest-images/sid-amd64-new.img', '10000000000'] None {}
2017-09-07 16:11:54 INFO Creating partitions
2017-09-07 16:11:54 DEBUG runcmd: ['parted', '-s', '/srv/autopkgtest-images/sid-amd64-new.img', 'mklabel', 'msdos'] None {}
2017-09-07 16:11:54 DEBUG runcmd: ['parted', '-s', '/srv/autopkgtest-images/sid-amd64-new.img', 'mkpart', 'primary', '0%', '100%'] None {}
2017-09-07 16:11:54 DEBUG runcmd: ['parted', '-s', '/srv/autopkgtest-images/sid-amd64-new.img', 'set', '1', 'boot', 'on'] None {}
2017-09-07 16:11:54 DEBUG runcmd: ['kpartx', '-avs', '/srv/autopkgtest-images/sid-amd64-new.img'] None {}
2017-09-07 16:11:54 INFO Creating filesystem ext4
2017-09-07 16:11:54 DEBUG runcmd: ['mkfs', '-t', 'ext4', u'/dev/mapper/loop0p1'] None {}
2017-09-07 16:11:55 DEBUG mkdir /tmp/tmpSEWpRs
2017-09-07 16:11:55 INFO Mounting /dev/mapper/loop0p1 on /tmp/tmpSEWpRs
2017-09-07 16:11:55 DEBUG runcmd: ['mount', u'/dev/mapper/loop0p1', '/tmp/tmpSEWpRs'] None {}

Then goes on with debootstrap but at this point already you are past the point
where the kernel should have emitted the uevent that triggers the by-uuid symlink
creation.

Cheers,
-- 
Raphaël Hertzog ◈ Debian Developer

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