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Re: [MINI-OS PATCH v2 07/14] mini-os: kexec: add support for handing over some memory across kexec


  • To: Juergen Gross <jgross@xxxxxxxx>, <minios-devel@xxxxxxxxxxxxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxxx>
  • From: Jason Andryuk <jason.andryuk@xxxxxxx>
  • Date: Tue, 15 Jul 2025 13:56:17 -0400
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  • Cc: <samuel.thibault@xxxxxxxxxxxx>
  • Delivery-date: Tue, 15 Jul 2025 17:56:41 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On 2025-07-15 09:29, Juergen Gross wrote:
Especially for support of Xenstore-stubdom live update some memory must
be handed over to the new kernel without moving it around: as the
9pfs device used for storing and retrieving the state of Xenstore
needs to be kept operational across kexec (it can't be reopened due to
Xenstore not being available without access to the device), the ring
pages need to be accessible via active grants by the backend all the
time.

Add the basic support for that by reserving a pre-defined number of
memory pages at the top of the memory. This memory area will be
handed over to the new kernel via specifying it as a module in
struct hvm_start_info.

The contents of the memory area are described via a generic table of
contents in the last page of the memory.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>

Reviewed-by: Jason Andryuk <jason.andryuk@xxxxxxx>

Thanks for the expanded comment.

Regards,
Jason



 


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