Boot diagnostic: Initramfs unpacking failed: Decoding failed

[David Coe]

AMD 2400G dual-booting Eoan and Focal (beta) gives both unpacking and IOMMU diagnostics. Earlier CPUs (eg AMD FX-8350) only show the initramfs unpacking failure. Neither failure appears fatal!

Booting Eoan, boot screen diagnostic ...

     AMD-Vi: Unable to read/write to IOMMU perf counter

dmesg diagnostic ...

[ 0.226916] PCI: CLS 64 bytes, default 64
[ 0.226954] Trying to unpack rootfs image as initramfs...
[ 0.354744] Initramfs unpacking failed: Decoding failed
[ 0.354754] fbcon: Taking over console
[ 0.363736] Freeing initrd memory: 75116K
[ 0.363852] pci 0000:00:00.2: AMD-Vi: Unable to read/write to IOMMU perf counter.
[ 0.363964] pci 0000:00:00.2: can't derive routing for PCI INT A
[ 0.363965] pci 0000:00:00.2: PCI INT A: not connected

Booting Focal, boot screen is clean

dmesg diagnostic ...

[ 0.223341] PCI: CLS 64 bytes, default 64
[ 0.223389] Trying to unpack rootfs image as initramfs...
[ 0.360518] Initramfs unpacking failed: Decoding failed
[ 0.369668] Freeing initrd memory: 78244K
[ 0.369778] pci 0000:00:00.2: AMD-Vi: Unable to read/write to IOMMU perf counter.
[ 0.369879] pci 0000:00:00.2: can't derive routing for PCI INT A
[ 0.369880] pci 0000:00:00.2: PCI INT A: not connected

There is a lot of comment (and inconclusive workarounds) in <https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1835660> on the unpacking issue. The diagnostic can be removed by changing lz4 to gzip in /etc/initramfs-tools/initramfs.conf and rerunning update-initramfs -u.

I can't find guidance on the IOMMU problem - it's just concealed by grub configured not to take over the fbcon console and (presumably) affects the VGA port.

Both may require upstream attention (with the kernel) rather than with with the grub code or configuration. Could you route as appropriate? My thanks!

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: grub-efi-amd64-signed 1.137+2.04-1ubuntu22
ProcVersionSignature: Ubuntu 5.4.0-21.25-generic 5.4.27
Uname: Linux 5.4.0-21-generic x86_64
ApportVersion: 2.20.11-0ubuntu22
Architecture: amd64
CurrentDesktop: KDE
Date: Sat Apr 4 22:46:04 2020
InstallationDate: Installed on 2020-04-03 (1 days ago)
InstallationMedia: Kubuntu 20.04 LTS "Focal Fossa" - Beta amd64 (20200401)
SourcePackage: grub2-signed
UpgradeStatus: No upgrade log present (probably fresh install)