From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Vrabel <david.vrabel@citrix.com>
Subject: Re: [PATCHv9 0/9] Xen: extend kexec hypercall for use
 with pv-ops kernels
Date: Fri, 11 Oct 2013 10:56:25 +0100
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To: Jan Beulich <JBeulich@suse.com>
Cc: Daniel Kiper <daniel.kiper@oracle.com>, Keir Fraser <keir@xen.org>, Daniel Kiper <dkiper@net-space.pl>, xen-devel@lists.xen.org
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On 11/10/13 07:49, Jan Beulich wrote:
>>>> On 10.10.13 at 23:24, Daniel Kiper <daniel.kiper@oracle.com> 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.
+ *
+ * - Local interrupts are disabled.
+ *
+ * - Register values are undefined.
+ *
+ * - The image segments have writeable 1:1 virtual to machine mappings.
+ *   The location of the page tables is undefined and the page table
+ *   frames are not be mapped.
  */
 #define KEXEC_CMD_kexec                 0
 typedef struct xen_kexec_exec {

David