# Determine the boot mode parameter of an Amazon EC2 AMI
<a name="ami-boot-mode"></a>

The AMI boot mode parameter is optional. An AMI can have one of the following boot mode parameter values: `uefi`, `legacy-bios`, or `uefi-preferred`.

Some AMIs don't have a boot mode parameter. When an AMI has no boot mode parameter, the instances launched from the AMI use the default value of the instance type, which is `uefi` on Graviton, and `legacy-bios` on Intel and AMD instance types.

------
#### [ Console ]

**To determine the boot mode parameter of an AMI**

1. Open the Amazon EC2 console at [https://console.aws.amazon.com/ec2/](https://console.aws.amazon.com/ec2/).

1. In the navigation pane, choose **AMIs**, and then select the AMI.

1. Inspect the **Boot mode** field.
   + A value of **uefi** indicates that the AMI supports UEFI.
   + A value of **uefi-preferred** indicates that the AMI supports both UEFI and Legacy BIOS.
   + If there is no value, the instances launched from the AMI use the default value of the instance type.

**To determine the boot mode parameter of an AMI when launching an instance**  
When launching an instance using the launch instance wizard, at the step to select an AMI, inspect the **Boot mode** field. For more information, see [Application and OS Images (Amazon Machine Image)](ec2-instance-launch-parameters.md#liw-ami).

------
#### [ AWS CLI ]

**To determine the boot mode parameter of an AMI**  
Use the [https://docs.aws.amazon.com/cli/latest/reference/ec2/describe-images.html](https://docs.aws.amazon.com/cli/latest/reference/ec2/describe-images.html) command to determine the boot mode of an AMI.

```
aws ec2 describe-images \
    --region us-east-1 \
    --image-id ami-0abcdef1234567890 \
    --query Images[].BootMode \
    --output text
```

The following is example output.

```
uefi
```

In the output, a value of `uefi` indicates that the AMI supports UEFI. A value of `uefi-preferred` indicates that the AMI supports both UEFI and Legacy BIOS. If there is no value, the instances launched from the AMI use the default value of the instance type.

------
#### [ PowerShell ]

**To determine the boot mode parameter of an AMI**  
Use the [https://docs.aws.amazon.com/powershell/latest/reference/items/Get-EC2Image.html](https://docs.aws.amazon.com/powershell/latest/reference/items/Get-EC2Image.html) cmdlet to determine the boot mode of an AMI.

```
Get-EC2Image -Region us-east-1 `
    -ImageId ami-0abcdef1234567890 | Format-List Name, BootMode, TpmSupport
```

The following is example output.

```
Name       : TPM-Windows_Server-2016-English-Full-Base-2023.05.10
BootMode   : uefi
TpmSupport : v2.0
```

In the output, the value of `BootMode` indicates the boot mode of the AMI. A value of `uefi` indicates that the AMI supports UEFI. A value of `uefi-preferred` indicates that the AMI supports both UEFI and Legacy BIOS. If there is no value, the instances launched from the AMI use the default value of the instance type.

------