Re: [Xen-devel] [PATCH 22/27] docs/libxl: [RFC] Introduce CHECKPOINT_END to support migration v2 remus streams

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Mon, 2015-06-15 at 14:44 +0100, Andrew Cooper wrote:
> In a remus senario, libxc will write a CHECKPOINT record, then hand ownership

"scenario"

> of the fd to libxl.  Libxl then writes any records required and finishes with
> a CHECKPOINT_END record, then hands ownership of the fd back to libxc.

Seems like a plausible scheme to me, if that's what the RFC was for.

> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> CC: Ian Campbell <Ian.Campbell@xxxxxxxxxx>
> CC: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
> CC: Wei Liu <wei.liu2@xxxxxxxxxx>
> ---
>  docs/specs/libxl-migration-stream.pandoc |   15 ++++++++++++++-
>  tools/libxl/libxl_sr_stream_format.h     |    1 +
>  tools/python/xen/migration/libxl.py      |   11 +++++++++++
>  3 files changed, 26 insertions(+), 1 deletion(-)
> 
> diff --git a/docs/specs/libxl-migration-stream.pandoc 
> b/docs/specs/libxl-migration-stream.pandoc
> index 7235317..d41932a 100644
> --- a/docs/specs/libxl-migration-stream.pandoc
> +++ b/docs/specs/libxl-migration-stream.pandoc
> @@ -119,7 +119,9 @@ type         0x00000000: END
>  
>               0x00000003: EMULATOR_CONTEXT
>  
> -             0x00000004 - 0x7FFFFFFF: Reserved for future _mandatory_
> +             0x00000004: CHECKPOINT_END
> +
> +             0x00000005 - 0x7FFFFFFF: Reserved for future _mandatory_
>               records.
>  
>               0x80000000 - 0xFFFFFFFF: Reserved for future _optional_
> @@ -203,3 +205,14 @@ index            Index of this emulator for the domain, 
> if multiple
>  
>  emulator_ctx     Emulator context blob.
>  --------------------------------------------------------------------
> +
> +CHECKPOINT_END
> +--------------
> +
> +A checkpoint end record marks the end of a checkpoint in the image.
> +
> +     0     1     2     3     4     5     6     7 octet
> +    +-------------------------------------------------+
> +
> +The end record contains no fields; its body_length is 0.
> +
> diff --git a/tools/libxl/libxl_sr_stream_format.h 
> b/tools/libxl/libxl_sr_stream_format.h
> index 487f9e2..5dfa55f 100644
> --- a/tools/libxl/libxl_sr_stream_format.h
> +++ b/tools/libxl/libxl_sr_stream_format.h
> @@ -35,6 +35,7 @@
>  #define REC_TYPE_LIBXC_CONTEXT       0x00000001U
>  #define REC_TYPE_XENSTORE_DATA       0x00000002U
>  #define REC_TYPE_EMULATOR_CONTEXT    0x00000003U
> +#define REC_TYPE_CHECKPOINT_END      0x00000004U
>  
>  typedef struct libxl_sr_emulator_hdr
>  {
> diff --git a/tools/python/xen/migration/libxl.py 
> b/tools/python/xen/migration/libxl.py
> index 4e1f4f8..415502e 100644
> --- a/tools/python/xen/migration/libxl.py
> +++ b/tools/python/xen/migration/libxl.py
> @@ -36,12 +36,14 @@ REC_TYPE_end              = 0x00000000
>  REC_TYPE_libxc_context    = 0x00000001
>  REC_TYPE_xenstore_data    = 0x00000002
>  REC_TYPE_emulator_context = 0x00000003
> +REC_TYPE_checkpoint_end   = 0x00000004
>  
>  rec_type_to_str = {
>      REC_TYPE_end              : "End",
>      REC_TYPE_libxc_context    : "Libxc context",
>      REC_TYPE_xenstore_data    : "Xenstore data",
>      REC_TYPE_emulator_context : "Emulator context",
> +    REC_TYPE_checkpoint_end   : "Checkpoint end",
>  }
>  
>  # emulator_context
> @@ -176,6 +178,13 @@ class VerifyLibxl(VerifyBase):
>          self.info("  Index %d, type %s" % (emu_idx, 
> emulator_id_to_str[emu_id]))
>  
> 
> +    def verify_record_checkpoint_end(self, content):
> +        """ Checkpoint end record """
> +
> +        if len(content) != 0:
> +            raise RecordError("Checkpoint end record with non-zero length")
> +
> +
>  record_verifiers = {
>      REC_TYPE_end:
>          VerifyLibxl.verify_record_end,
> @@ -185,4 +194,6 @@ record_verifiers = {
>          VerifyLibxl.verify_record_xenstore_data,
>      REC_TYPE_emulator_context:
>          VerifyLibxl.verify_record_emulator_context,
> +    REC_TYPE_checkpoint_end:
> +        VerifyLibxl.verify_record_checkpoint_end,
>  }



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