Re: [Xen-devel] [RFC PATCH 0/3] Improve kexec support in Xen hypervisor

[Daniel Kiper <daniel.kiper@xxxxxxxxxx>]

On Wed, Jan 16, 2013 at 04:29:03PM +0000, David Vrabel wrote:
> This series of patches improves the kexec hypercall in the Xen
> hypervisor.  It is an incomplete prototype but I posting it early for
> comments on the proposed ABI/API.
>
> This allows a privileged Xen guest to load kexec images into the
> hypervisor from a userspace tool without using the Linux kernel's
> kexec subsystem.  It is the first step to supporting kexec of crash
> kernels from a pv-ops dom0 kernel (the required kernel and kexec-tools
> patches will be posted later).
>
> The kernel will require a kexec hypercall somewhere in the
> crash_kexec() path to actually exec the loaded image.  Any preferences
> on how the hook for this should be implemented?  Note that the kernel

This should be implemented as stub which be called by machine_kexec()
and later it would call relevant hypercall.

> won't be aware that an image as been loaded as it is loaded directly
> into the hypervisor and not via the kernel's kexec_load system call.

Maybe we should have sepcial kexec hypercall function which allow us
to ask hypervisor that image is loaded or not.

> Since the kexec hypercall is for use by dom0 I have removed the
> implementation of the old load/unload ops and thus guests will require
> updated kexec-tools to load images.  Is this acceptable?

Not yet. I think that old interface should stay as long as Xen Linux Kernel
could run on latest versions of hypervisor.

Daniel

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