Determine the boot mode of an EC2 instance - Amazon Elastic Compute Cloud
Services or capabilities described in Amazon Web Services documentation might vary by Region. To see the differences applicable to the China Regions, see Getting Started with Amazon Web Services in China (PDF).

Determine the boot mode of an EC2 instance

The boot mode of an instance is displayed in the Boot mode field in the Amazon EC2 console, and by the currentInstanceBootMode parameter in the Amazon CLI.

When an instance is launched, the value for its boot mode parameter is determined by the value of the boot mode parameter of the AMI used to launch it, as follows:

  • An AMI with a boot mode parameter of uefi creates an instance with a currentInstanceBootMode parameter of uefi.

  • An AMI with a boot mode parameter of legacy-bios creates an instance with a currentInstanceBootMode parameter of legacy-bios.

  • An AMI with a boot mode parameter of uefi-preferred creates an instance with a currentInstanceBootMode parameter of uefi if the instance type supports UEFI; otherwise, it creates an instance with a currentInstanceBootMode parameter of legacy-bios.

  • An AMI with no boot mode parameter value creates an instance with a currentInstanceBootMode parameter value that is dependent on whether the AMI architecture is ARM or x86 and the supported boot mode of the instance type. The default boot mode is uefi on Graviton instance types, and legacy-bios on Intel and AMD instance types.

Console
To determine the boot mode of an instance (console)

  1. Open the Amazon EC2 console at https://console.amazonaws.cn/ec2/.

  2. In the navigation pane, choose Instances, and then select your instance.

  3. On the Details tab, inspect the Boot mode field.

Amazon CLI
To determine the boot mode of an instance

Use the describe-instances command to determine the boot mode of an instance. You can also determine the boot mode of the AMI that was used to the create the instance. 

aws ec2 describe-instances --region us-east-1 --instance-ids i-1234567890abcdef0

{
    "Reservations": [
        {
            "Groups": [],
            "Instances": [
                {
                    "AmiLaunchIndex": 0,
                    "ImageId": "ami-0e2063e7f6dc3bee8",
                    "InstanceId": "i-1234567890abcdef0",
                    "InstanceType": "m5.2xlarge",
                    ... 
                    },
                   "BootMode": "uefi",
                   "CurrentInstanceBootMode": "uefi"
                }
            ],
            "OwnerId": "1234567890",
            "ReservationId": "r-1234567890abcdef0"
        }
    ]
}
PowerShell
To determine the boot mode of an instance (Tools for PowerShell)

Use the Get-EC2Image Cmdlet to determine the boot mode of an instance. You can also determine the boot mode of the AMI that was used to the create the instance.

Get-EC2Image (Amazon Tools for Windows PowerShell)

(Get-EC2Instance -InstanceId i-1234567890abcdef0).Instances | Format-List BootMode, CurrentInstanceBootMode, InstanceType, ImageId 
					
BootMode                : uefi
CurrentInstanceBootMode : uefi
InstanceType            : c5a.large
ImageId                 : ami-0265446f88eb4021b

In the output, the following parameters describe the boot mode:

  • BootMode – The boot mode of the AMI that was used to create the instance.

  • CurrentInstanceBootMode – The boot mode that is used to boot the instance at launch or start.