Remus PV domU requirements

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Remus supports most domU guests that can be run in PV, however, you may see this warning when you start Remus:

"WARNING: suspend event channel unavailable, falling back to slow xenstore signalling"

This means the kernel in the guest doesn't have "suspend event channel" support, which in turn basically Remus is going to work, but isn't going to perform well.

  • At the time of the Xen 4.5 release, the PVOPS kernel does not support this feature
  • At the time of writing, Ubuntu kernels do not generally have suspend event channel support
  • On the subject of adding support to a kernel's source, according to the author of Remus, "It is not a config option. It requires some code modification and cannot be selectively enabled, in a clean way."
  • The linux-2.6.18-xen.hg kernel from Xen does have support, but is old these days and probably not a great choice
  • OpenSUSE natively supports suspend event channel support, and is a good choice for testing
  • Yes, this does mean that it's not necessarily easy to start using Remus for production with any given domU in PV
  • Note: You can instead run your VM in HVM without requiring this support, if that is an option for you

References