Hi,

I have a Debian VPS with Linode. Why does it come with an external Linode kernel?

I'm aware[1] that I can opt to reconfigure with a stock Debian kernel, but why should I have to? Why is the external kernel the default? Is this something to do with Xen (most hosts I use use KVM)?

What benefit does it add (to Linode or to the customer)?

[1]: See https://www.linode.com/docs/tools-reference/custom-kernels-distros/run-a-custom-compiled-kernel-with-pvgrub - complete with its broken link to "running a distribution-supplied kernel" at https://www.linode.com/docs/linode-platform/custom-instances/pv-grub-howto

I have tested both at home (Xen and KVM), and using an external kernel is the default in Xen, yes.

The main benefit I see is that you can be sure that it will work.

Also, you save about 165 MB in the root partition (math done on a Debian 8 system).

There are also historical reasons; before Xen guest support was in the mainline kernel, a special configuration was needed. Customizations might have also been required when Linode used UML, but I can't remember back that far. Over time, the management interface and user community has developed a built-in assumption that Linode will provide the kernel.