Dhcpcd prioritizes (unconnnected) LAN adapter over WLAN, causing a 5 min boot delay

[Albert Weichselbraun]

After upgrading to Ubuntu 24.04, dhcpcd spends over five minutes trying to obtain a DHCP lease for an unconnected LAN adapter during startup.
Only after this process times out, the boot process resumes.

Consequently, startup works flawlessly, if the laptop is connected to the LAN, but takes five additional minutes, if that's not the case.

Please find below the console output (obtained by pressing "ESC" during bootup)

Setting ip link enp0s... up
Setting ip link enx0... up
dhcpcd-10.0.6 starting
dev: loaded udev
no interfaces have a carrier
exiting due to oneshot
Sleeping 30 seconds before retrying getting a DHCP lease
dhcpcd-10.0.6 starting
dev: loaded udev
no interfaces have a carrier
exiting due to oneshot
Sleeping 60 seconds before retrying getting a DHCP lease
...
dhcpcd-10.0.6 starting
dev: loaded udev
no interfaces have a carrier
exiting due to oneshot
Sleeping 120 seconds before retrying getting a DHCP lease

After multiples tries to obtain a DHCP lease (which take approximately five minutes) the standard boot process resumes.

ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: initramfs-tools 0.142ubuntu25
ProcVersionSignature: Ubuntu 6.8.0-22.22-generic 6.8.1
Uname: Linux 6.8.0-22-generic x86_64
ApportVersion: 2.28.1-0ubuntu1
Architecture: amd64
CasperMD5CheckMismatches: ./preseed/ubuntu.seed ./pool/restricted/n/nvidia-graphics-drivers-535/nvidia-firmware-535-535.113.01_535.113.01-0ubuntu3_amd64.deb ./pool/restricted/n/nvidia-graphics-drivers-535/xserver-xorg-video-nvidia-535_535.113.01-0ubuntu3_amd64.deb ./pool/restricted/n/nvidia-graphics-drivers-535/nvidia-compute-utils-535_535.113.01-0ubuntu3_amd64.deb ./pool/restricted/n/nvidia-graphics-drivers-535/nvidia-kernel-source-535_535.113.01-0ubuntu3_amd64.deb ./pool/restricted/n/nvidia-graphics-drivers-535/nvidia-driver-535_535.113.01-0ubuntu3_amd64.deb ./pool/restricted/n/nvidia-graphics-drivers-535/nvidia-utils-535_535.113.01-0ubuntu3_amd64.deb ./pool/restricted/n/nvidia-graphics-drivers-535/nvidia-kernel-common-535_535.113.01-0ubuntu3_amd64.deb ./pool/restricted/n/nvidia-graphics-drivers-535/libnvidia-gl-535_535.113.01-0ubuntu3_i386.deb
CasperMD5CheckResult: fail
CurrentDesktop: ubuntu:GNOME
Date: Fri Apr 19 07:40:31 2024
InstallationDate: Installed on 2023-12-03 (138 days ago)
InstallationMedia: Ubuntu Legacy 23.10 "Mantic Minotaur" - Release amd64 (20231010)
PackageArchitecture: all
SourcePackage: initramfs-tools
UpgradeStatus: Upgraded to noble on 2024-04-18 (1 days ago)

[Benjamin Drung (bdrung)]

Thank you for taking the time to report this bug and contributing to Ubuntu. Is the LAN adapter the only network device on your machine? What are you kernel cmdline parameters?

[Albert Weichselbraun (albert-weichselbraun)]

The machine has a Wifi and a LAN adapter:

<snip cmd="lspci |grep -i net">
00:1f.6 Ethernet controller: Intel Corporation Ethernet Connection (4) I219-LM (rev 21)
01:00.0 Network controller: Intel Corporation Wireless 8265 / 8275 (rev 78)
</snip>

Kernel cmdline parameters:

<snip cmd="cat /proc/cmdline">
BOOT_IMAGE=/vmlinuz-6.8.0-22-generic root=UUID=50fe4fec-39c1-4ec0-8401-328516b4fa86 ro quiet splash i915.enable_psr=0
</snip>

[Benjamin Drung (bdrung)]

I see no ip parameter on the kernel cmdline. So dhcpcd should not run in the initramfs at all. Can you boot with `debug` and share the /run/initramfs/initramfs.debug then?

[Albert Weichselbraun (albert-weichselbraun)]

Sure - please find enclosed /run/initramfs/initramfs.debug

It looks like the problem is caused by `configure_networking` from `/usr/share/initramfs-tools/scripts/functions` which is called due to the installed `aoetools` package (which calls `configure_networking` in `/usr/share/initramfs-tools/scripts/local-top/aoe`).

[Benjamin Drung (bdrung)]

Thanks for the analysis. My conclusion is: initramfs-tools works as designed. The culprit is aoetools here.

Uninstalling aoetools would be one option. If that is not an option, aoetools should become smarter and only call `configure_networking` in case it needs an ATA over Ethernet device for booting. If the root UUID can be found locally, no network configuration is needed.

[Albert Weichselbraun (albert-weichselbraun)]

Thank you for helping debug this issue. I concur with your assessment.
- this should be handled by aoetools (probably similar to the way nfs versus nfsroot is handled).

[Benjamin Drung (bdrung)]

Thanks. Then I mark this bug as Invalid for initramfs-tools.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.