chreipl aborts - Installation workaround for NVMe IPL

This document (000020258) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 15 SP3
IBM zSeries

Situation

The chreipl tool (part of s390-tools) selects the boot device to use after a reboot.
It is typically run at the end of an installer workflow, when the installed system is started for the first time.
Starting with version 2.14, the chreipl tool supports specifying NVMe devices as boot device.

When the target NVMe device supports multipathing, that is when the device's Controller Multi-Path I/O and Namespace Sharing Capabilities indicates that the NVMe subsystem may contain two or more controllers (CMIC bit 1 set).

The chreipl tool aborts with an error message:

chreipl: Could not read from "/sys/block/nvme0n1/device/device/function_id" (No such file or directory)

The target NVMe device is not correctly selected for reboot and the guest will not automatically boot into the installed system.

Resolution

Setting the "nvme-core.multipath=0" Kernel parameter as workaround makes a "chreipl node" succeed with NVMe devices.
This is needed for the installer only, not for the installed system.

Note:
The actual firmware boot support is not affected.
Assuming everything else is setup properly, a manually initiated boot from the associated NVMe device should still succeed.

Cause

Currently chreipl is missing multipath support.

Status

Reported to Engineering

Disclaimer

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