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I am booting up some Amazon EC2 instances. Specifically, Alestic instances in us-east for Ubuntu 10.04, 10.10 and 11.04. When I log into those machines I can use "uname -a" to check the kernel versions. And as expected, they are different: 2.6.32, 2.6.35 and 2.6.38.

To my great surprise, however, their AKI is actually the same! That is shown in the web-based management portal, and also by the ec2-describe-instances command.

When I look into the /boot directory, I can see the kernel image files, such as vmlinuz-2.6.38-8-virtual. The names are appropriate for what "uname -a" shows on that instance and they are also of different sizes.

So, what is going on here? I was under the impression that you can use specific AKIs to get different kernels in your machines. Here I see different kernels, but the same AKI?

If you could help me to understand this, I would much appreciate it.

Thank you very much...

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If this is using the pvgrub method ("User Provided Kernel"), the base aki is the same because it's chain loading into a user-defined (by Altesic) kernel. This is how kernels may now be (carefully) upgraded without breaking your box in previous AMIs.

Check that the AKI matches one listed in the PDF below.


"Enabling User Provided Kernels in Amazon EC2"

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