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Re: [Xen-devel] [PATCH v4 03/14] libxc/migration: Specification update for CHECKPOINT records

On 05/12/2015 08:05 PM, Andrew Cooper wrote:
On 12/05/15 12:25, Yang Hongyang wrote:
From: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Checkpointed streams need to signal the end of a consistent view of VM state,
and the start of the libxl data.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
Signed-off-by: Yang Hongyang <yanghy@xxxxxxxxxxxxxx>
CC: Ian Campbell <Ian.Campbell@xxxxxxxxxx>
CC: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
CC: Wei Liu <wei.liu2@xxxxxxxxxx>
  docs/specs/libxc-migration-stream.pandoc | 33 +++++++++++++++++++++++++++++---
  tools/libxc/xc_sr_common.c               |  1 +
  tools/libxc/xc_sr_stream_format.h        |  1 +
  3 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/docs/specs/libxc-migration-stream.pandoc 
index 520240f..842938c 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_

               0x80000000 - 0xFFFFFFFF: Reserved for future _optional_
@@ -578,6 +578,33 @@ The verify record contains no fields; its body_length is 0.


+A checkpoint record indicates that all the preceding records 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.

The above paragraph needs deleting.  It was my mistake for not deleting
it in my series.

Ok, will delete it.


+If the stream is embedded in a higher level toolstack stream, the
+CHECKPOINT record marks the end of the libxc portion of the stream
+and the stream is handed back to the higher level for further
+The higher level stream may then hand the stream back to libxc to
+process another set of records for the next consistent VM state
+snapshot.  This next set of records may be terminated by another
+CHECKPOINT record or an END record.

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 @@ static const char *mandatory_rec_types[] =
      [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 
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



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