Re: [PATCH v3 3/6] libxc/migration: Specification update for CHECKPOINT records

[Yang Hongyang <yanghy@cn.fujitsu.com>]

On 05/12/2015 05:35 PM, Andrew Cooper wrote:
> Checkpointed streams need to signal the end of a consistent view of VM state,
> and the start of the libxl data.

Ah, now I know what's CHECKPOINT record mean, the name is OK for me then.

>
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
> CC: David Vrabel <david.vrabel@citrix.com>
> CC: Ian Campbell <Ian.Campbell@citrix.com>
> CC: Ian Jackson <Ian.Jackson@eu.citrix.com>
> CC: Wei Liu <wei.liu2@citrix.com>
> CC: Yang Hongyang <yanghy@cn.fujitsu.com>
>
> ---
>
> After discusions with David, we have come to the conclusion that a CHECKPOINT
> record alone is sufficient for the remus case.  There is no functional need to
> explicitly identify the stream as being of arbitrary length.
> ---
>   docs/specs/libxc-migration-stream.pandoc |   23 ++++++++++++++++++++---
>   tools/libxc/xc_sr_common.c               |    1 +
>   tools/libxc/xc_sr_stream_format.h        |    1 +
>   3 files changed, 22 insertions(+), 3 deletions(-)
>
> diff --git a/docs/specs/libxc-migration-stream.pandoc b/docs/specs/libxc-migration-stream.pandoc
> index 520240f..97edd7d 100644
> --- a/docs/specs/libxc-migration-stream.pandoc
> +++ b/docs/specs/libxc-migration-stream.pandoc
> @@ -37,8 +37,6 @@ Not Yet Included
>   The following features are not yet fully specified and will be
>   included in a future draft.
>
> -* Remus
> -
>   * Page data compression.
>
>   * ARM
> @@ -227,7 +225,9 @@ type         0x00000000: END
>
>                0x0000000D: VERIFY
>
> -             0x0000000E - 0x7FFFFFFF: Reserved for future _mandatory_
> +             0x0000000E: CHECKPOINT
> +
> +             0x0000000F - 0x7FFFFFFF: Reserved for future _mandatory_
>                records.
>
>                0x80000000 - 0xFFFFFFFF: Reserved for future _optional_
> @@ -578,6 +578,23 @@ The verify record contains no fields; its body_length is 0.
>
>   \clearpage
>
> +CHECKPOINT
> +----------
> +
> +A checkpoint record indicates that the records thusfar in the stream represent
> +a consistent view of VM state.
> +
> +     0     1     2     3     4     5     6     7 octet
> +    +-------------------------------------------------+
> +
> +The checkpoint record contains no fields; its body_length is 0
> +
> +A stream containing checkpoint records must have indicated itself as a
> +checkpointed stream in the Image Header.  Conversely, a stream not identified
> +as checkpointed must not contain checkpoint records.
> +
> +\clearpage
> +
>   Layout
>   ======
>
> diff --git a/tools/libxc/xc_sr_common.c b/tools/libxc/xc_sr_common.c
> index 59e0c5d..945cfa6 100644
> --- a/tools/libxc/xc_sr_common.c
> +++ b/tools/libxc/xc_sr_common.c
> @@ -34,6 +34,7 @@ const char *dhdr_type_to_str(uint32_t type)
>       [REC_TYPE_TOOLSTACK]            = "Toolstack",
>       [REC_TYPE_X86_PV_VCPU_MSRS]     = "x86 PV vcpu msrs",
>       [REC_TYPE_VERIFY]               = "Verify",
> +    [REC_TYPE_CHECKPOINT]           = "Checkpoint",
>   };
>
>   const char *rec_type_to_str(uint32_t type)
> diff --git a/tools/libxc/xc_sr_stream_format.h b/tools/libxc/xc_sr_stream_format.h
> index d116ca6..6d0f8fd 100644
> --- a/tools/libxc/xc_sr_stream_format.h
> +++ b/tools/libxc/xc_sr_stream_format.h
> @@ -74,6 +74,7 @@ struct xc_sr_rhdr
>   #define REC_TYPE_TOOLSTACK            0x0000000bU
>   #define REC_TYPE_X86_PV_VCPU_MSRS     0x0000000cU
>   #define REC_TYPE_VERIFY               0x0000000dU
> +#define REC_TYPE_CHECKPOINT           0x0000000eU
>
>   #define REC_TYPE_OPTIONAL             0x80000000U
>
>

-- 
Thanks,
Yang.