Ubuntu
initramfs-tools package

Mantic/23.10: PXE boot tries to initialize DHCP before network link is up

Bug #2037202 reported by Marian Rainer-Harbach
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
initramfs-tools (Ubuntu)
Fix Released
Undecided
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Bug Description

I'm not sure whether this is the correct package for this bug, please reassign if not.

I'm booting the Ubuntu Mantic/23.10 desktop beta image via PXE in order to perform an unattended installation. The kernel command line looks like that:

iso/casper/vmlinuz --- ip=dhcp netboot=nfs nfsroot=192.168.1.1:/export/ubuntu autoinstall ds=nocloud\;s=<removed>

This has worked perfectly before. However, in 23.10, the kernel tries to intialize DHCP before a network link is up.

I can see a few instances of messages like the following:
dhcpcd-10.0.2 starting
dev: loaded udev
no interfaces have a carrier
exiting due to oneshot
dhcpcd exited

Then, the kernel tries to mount NFS, even though neither an IP address nor even a link is available:
connect: Network is unreachable
NFS over TCP not available from 192.168.1.1

This is repeated for a while. In between, a message tells that now the link is up:
[ 10.0002805] e1000e 0000:00:19.0 enp0s25: NIC Link is Up 1000 Mbps Full Duplex, Flow Control: Rx/Tx

The NFS messages repeat for a while, until the system gives up and I'm dropped into a busybox prompt.

Executing dhcpcd now correctly gets IP addresses, but I don't know how to continue the boot from there.

The problem occurs on most physical machines that I tried, but not in VMs.

See original description

Related branches

~mwhudson/ubuntu/+source/initramfs-tools:ubuntu/mantic-proposed
Steve Langasek (community): Approve
git-ubuntu import: Pending requested
Diff: 88 lines (+39/-22)
2 files modified
debian/changelog (+8/-0)
scripts/functions (+31/-22)
Marian Rainer-Harbach (marianrh)
tags: added: mantic
Marian Rainer-Harbach (marianrh)
description: updated
Benjamin Drung (bdrung)
tags: added: rls-mm-incoming
Revision history for this message
Marian Rainer-Harbach (marianrh) wrote :

As a workaround, I added a `sleep 1` at the end of `_set_available_devices_to_up()` in `scripts/functions` in the Mantic initrd.

Julian Andres Klode (juliank)
tags: added: foundations-todo
removed: rls-mm-incoming
Revision history for this message
Adrien Nader (adrien-n) wrote :

Should dhcp really be oneshot? I don't know what dhclient was doing (I guess it was dhclient before) but it sounds difficult to synchronize this properly. I imagine it's also possible to run the dhcp client in oneshot mode in a loop with maybe 3 iterations and "sleep 1" in between.

Revision history for this message
Marian Rainer-Harbach (marianrh) wrote :

If I understand the process correctly, dhcpcd is already run in a loop. But the loop is over too quickly if the interface takes a few seconds to come up.

Revision history for this message
Dimitri John Ledkov (xnox) wrote :

I request this to be considered release critical, as this prevents all kernel team & certification team deployments of mantic systems, inhibiting our ability to test SRUs on all architectures.

tags: added: rls-mm-incoming
Revision history for this message
Adrien Nader (adrien-n) wrote :

Thanks for the precision Marian.

Dimitri, do you know if the "sleep 1" works in practice?

Revision history for this message
Michael Hudson-Doyle (mwhudson) wrote :

Is the point here that dhcpcd -1 exits immediately if it finds no devices, even if it has a -t argument?

Revision history for this message
Michael Hudson-Doyle (mwhudson) wrote :

https://code.launchpad.net/~mwhudson/ubuntu/+source/initramfs-tools/+git/initramfs-tools/+merge/452586 might be a fix? Not tested at all.

Revision history for this message
Launchpad Janitor (janitor) wrote :

This bug was fixed in the package initramfs-tools - 0.142ubuntu15

---------------
initramfs-tools (0.142ubuntu15) mantic; urgency=medium

  * scripts/functions: do not fail to configure networking too quickly. In
    particular make sure an unsuccessful attempt to run DHCP takes at least
    $ROUNDTTT seconds. (LP: #2037202)

 -- Michael Hudson-Doyle <email address hidden> Wed, 04 Oct 2023 12:02:13 +1300

Changed in initramfs-tools (Ubuntu):
status: New → Fix Released
Revision history for this message
Marian Rainer-Harbach (marianrh) wrote :

I tested on two machines where the boot failed previously. With the new `scripts/functions`, the boot now works properly. Thanks you!

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