Take Control disk EFI Boot Verification

  • 7018215
  • 31-Oct-2016
  • 29-Nov-2016

Environment

Systems booted with the Take Control Disk

Situation

Using the Take Control Disk it may be necessary to determine if the source system booted using EFI or if it booted in BIOS mode.

Resolution

To determine if the Take Control Disk booted using EFI or BIOS mode, verify the boot parameters via the following command once a helper or debug console has been accessed via ALT_F7 or ALT_F2 respectively.

Execute the following command once a console has been accessed:

cat /proc/cmdline

The BOOT_IMAGE parameter specifies the location of the kernel booted from the Take Control Disk. The BOOT_IMAGE parameter provides information that can be used to determine if the source system booted up as BIOS or EFI.  The BOOT_IMAGE can also be used to determine if the Take Control Disk booted in 32 or 64 bit mode.

For BIOS systems  booting with the "ps" option, the output should look similar to this:

initrd=/i586/initrd.gz root=/dev/ram0 init=/linuxrc rw vga=0x34 ramdisk_size=15700 DEBUG=TRUE BOOT_IMAGE=/i586/vmlinuz

Note that the BOOT_IMAGE path is /i586. This suggests that the source was booted in BIOS mode with a 32 bit architecture.

For BIOS systems booting with the "ps64" option, the output should look similar to this:

initrd=/x86_64/initrd.gz root=/dev/ram0 init=/linuxrc rw vga=0x34 ramdisk_size=15700 DEBUG=TRUE BOOT_IMAGE=/x86_64/vmlinuz

The example above denotes an 64 bit architecture booted in BIOS Mode. 

For an EFI system, the bootloader is ELILO. If the ELILO information isn't seen at boot, the command will display the something similar to the following:

BOOT_IMAGE=dev001:\EFI\BOOT\vmlinux root=/dev/init=linuxrc rw vga=0x314 ramdisk_size=157000 DEBUG=TRUE

Note: EFI mode is not available on 32 bit architectures.

Cause

Incorrect BIOS settings, boot option selection or other issues may not allow a user to determine what mode the disk booted into.

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