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036 - EC2 user selectable Kernels

Amazon EC2 allows developers to use kernels other than the default Amazon EC2 kernels with their instances.
An Amazon Kernel Image(AKI) is similar to an Amazon Machine Image(AMI). The latter is prefixed with "ami-"
while the former is prefixed with "aki-". In addition, Amazon EC2 supports Amazon RAM disk images(ARI)
which might be required by kernels and are prefixed with "ari-".
Anyone can use alternative kernels or RAM disks with their AMIs, but the ability to create and publish
kernels and ramdisks is restricted to Amazon EC2 and selected vendors.

Finding Available Kernel Images (AKIs) and RAM disks (ARIs):

ec2-describe-images -o self -o amazon

This command lists your AMIs and Amazon's public AMIs, AKIs and ARIs. The output might not exactly match that
shown above. Look for the lines containing image IDs starting with “aki-” or “ari-” (or use command line tools like
grep to filter them out). These are kernels and RAM disks, respectively. You will need the kernel ID for the next step.

The architecture of your AMI, RAM disk, and kernel must match. Even then, there is no guarantee a given combination will function correctly or boot successfully if they weren’t designed to be used together. Review the AKI’s release notes to see if it requires a RAM disk.



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Story | by Dr. Radut