IBM Support

Limitations using the legacy only boot order option - Servers

Troubleshooting


Problem

When using the Unified Extensible Firmware Interface (UEFI) System Firmware, System Configuration, and Boot Management menu item "Boot Manager", you can use "Add Boot Option" to add various items to the boot order. One item is "Legacy Only". Placing "Legacy Only in front of "Universal Serial Bus (USB) Storage" doesn't work as expected. It causes the UEFI System Firmware to skip the USB Storage device. "Legacy Only" is used to override the default boot method for dual boot media. A UEFI capable Operating System (OS) may be distributed on media that will install on a legacy computer or a UEFI computer. The IBM systems that support UEFI also support compatibility with legacy mode. Adding "Legacy Only" in front of "CD/DVD ROM" is the override to tell the UEFI System Firmware to boot the dual bootable CD/DVD ROM in legacy mode.

Resolving The Problem

Source

RETAIN Tip:H194972

Symptom

When using the Unified Extensible Firmware Interface (UEFI) System Firmware, System Configuration, and Boot Management menu item "Boot Manager", you can use "Add Boot Option" to add various items to the boot order. One item is "Legacy Only".

Placing "Legacy Only in front of "Universal Serial Bus (USB) Storage" does not work as expected. It causes the UEFI System Firmware to skip the USB Storage device.

"Legacy Only" is used to override the default boot method for dual boot media. A UEFI capable Operating System (OS) may be distributed on media that will install on a legacy computer or a UEFI computer. The IBM systems that support UEFI also support compatibility with legacy mode. Adding "Legacy Only" in front of "CD/DVD ROM" is the override to tell the UEFI System Firmware to boot the dual bootable CD/DVD ROM in legacy mode.

Affected configurations

The system may be any of the following IBM servers:

  • iDataPlex dx360 M2 Server, type 6380, any model
  • iDataPlex dx360 M2 Server, type 7321, any model
  • iDataPlex dx360 M2 Server, type 7323, any model
  • BladeCenter HS22, type 7870, any model
  • System x3550 M2, type 7946, any model
  • System x3650 M2, type 7947, any model

This tip is not software specific.

This tip is not option specific.

Workaround

To ensure that USB Storage device boots in legacy mode

Verify the UEFI boot image \EFI\BOOT\BOOTX64.EFI does not exist on the USB Storage device. Using "Legacy Only" in front of USB Storage is not required as the USB Storage device can be modified to not be bootable in UEFI mode.

Additional Information

"Legacy Only" is meant to be used in two specific cases:

  • Before "CD/DVD ROM", to boot a dual boot media in legacy mode instead of UEFI mode.
  • With a normal boot order after "Legacy Only" (for example; CD, HardDisk0, PXE) and a bootable disk adapter that is not recognized by the UEFI System Firmware, is installed.

"Legacy Only" would only be needed to boot a USB Storage key that has been formatted bootable in legacy mode and also had the file \EFI\BOOT\BOOTX64.EFI on it. This would be a dual boot USB Storage device.

User will have to remove or rename the \EFI\BOOT\BOOTX64.EFI file to boot a dual boot USB Storage key in legacy mode on any of these UEFI system.

Document Location

Worldwide

Operating System

BladeCenter:Operating system independent / None

System x:Operating system independent / None

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Document Information

Modified date:
19 April 2023

UID

ibm1MIGR-5079724

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