PReP partition has 16 MB of size

This document (000020531) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 15 SP4
SUSE Linux Enterprise Server 15 SP3
SUSE Linux Enterprise Server 15 SP2
SUSE Linux Enterprise Server 15 SP1
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise Server 12 SP5
SUSE Linux Enterprise Server 12 SP4
SUSE Linux Enterprise Server 12 SP3
SUSE Linux Enterprise Server 12 SP2

Situation

After installing SLES on IBM Power the system fails to boot and prints the following error message:

PReP-BOOT : Unable to load full PReP image.
Loaded fb8000  out of fffe00  bytes.

PReP partition has 16 MB of size.

Resolution

The NVRAM variable real-base can be changed to accommodate the larger PReP image.
Boot the partition to the Restricted Open Firmware Prompt and run the following commands, which will change the NVRAM variable and then reboot the partition.

set_nvram_realbase 2000000
reset_partition

Cause

The memory region into which the bootloader can be loaded is defined by NVRAM variables load-base, which is where the bootloader/OS is loaded, and real-base, where Open Firmware is loaded. The image must fit within the two values. The partition's values for the NVRAM variables:

load-base = 0x4000
real-base = 0xc00000

With the current configuration, there is not enough room to load the 16MiB (0xfffe00 bytes) of PReP image.

Status

Reported to Engineering

Additional Information

Issue is reported to IBM. There is not yet an infrastructure in place for the bootloader/OS to adjust the NVRAM variables as needed. Work is underway in IBM Linux development to make those adjustments.

The reason the PReP partition has 16 MiB is because the device reports an optimal IO size of 16 MiB. And YaST tries by default to produce fully aligned partitions.

Note: Re-partitioning during Installation or in Rescue mode is not possible, even forcing PReP with 8 MB of size doesn't fix the non-booting issue.

Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.

Document ID:000020531
Creation Date: 30-Dec-2021
Modified Date:04-Jan-2022
- SUSE Linux Enterprise Server
- SUSE Linux Enterprise Server for SAP Applications

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