Re: [Xen-devel] [PATCHv9 0/9] Xen: extend kexec hypercall for use with pv-ops kernels

[Daniel Kiper <daniel.kiper@xxxxxxxxxx>]

On Fri, Oct 11, 2013 at 10:56:25AM +0100, David Vrabel wrote:
> On 11/10/13 07:49, Jan Beulich wrote:
> >>>> On 10.10.13 at 23:24, Daniel Kiper <daniel.kiper@xxxxxxxxxx> wrote:
> >> On Thu, Oct 10, 2013 at 05:35:39PM +0100, David Vrabel wrote:
> >>> The register state on executing the image is undefined (this is the
> >>> specified ABI), so there is no need to set the registers to any
> >>> particular value.
> >>
> >> So let's look into the docs.
> >
> > "docs"?
>
> Yes, we should have some.  How about this as a start?
>
> --- a/xen/include/public/kexec.h
> +++ b/xen/include/public/kexec.h
> @@ -105,7 +105,20 @@ typedef struct xen_kexec_image {
>   * Perform kexec having previously loaded a kexec or kdump kernel
>   * as appropriate.
>   * type == KEXEC_TYPE_DEFAULT or KEXEC_TYPE_CRASH [in]
> + *
> + * Control is transferred to the image entry point with the host in
> + * the following state.
> + *
> + * - The image may be executed on any PCPU and all other PCPUs are
> + *   stopped.

OK.

> + * - Local interrupts are disabled.

OK.

> + * - Register values are undefined.

If Linux and kexec guys state that they do not care then I do not care too.
Let's wait what will happen in "kexec: Clearing registers just before
jumping into purgatory" thread.

> + * - The image segments have writeable 1:1 virtual to machine mappings.

OK.

> + *   The location of the page tables is undefined and the page table
> + *   frames are not be mapped.

OK.

Daniel

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