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Re: [PATCH v2] docs: update xenstore-migration.md



On 28.05.20 10:53, Paul Durrant wrote:
-----Original Message-----
From: Xen-devel <xen-devel-bounces@xxxxxxxxxxxxxxxxxxxx> On Behalf Of Juergen 
Gross
Sent: 28 May 2020 09:22
To: xen-devel@xxxxxxxxxxxxxxxxxxxx
Cc: Juergen Gross <jgross@xxxxxxxx>; Stefano Stabellini 
<sstabellini@xxxxxxxxxx>; Julien Grall
<julien@xxxxxxx>; Wei Liu <wl@xxxxxxx>; Andrew Cooper 
<andrew.cooper3@xxxxxxxxxx>; Ian Jackson
<ian.jackson@xxxxxxxxxxxxx>; George Dunlap <george.dunlap@xxxxxxxxxx>; Jan Beulich 
<jbeulich@xxxxxxxx>
Subject: [PATCH v2] docs: update xenstore-migration.md

Update connection record details: make flags common for sockets and
domains, and add pending incoming data.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
V2:
- added out-resp-len to connection record
---
  docs/designs/xenstore-migration.md | 71 +++++++++++++++++-------------
  1 file changed, 40 insertions(+), 31 deletions(-)

diff --git a/docs/designs/xenstore-migration.md 
b/docs/designs/xenstore-migration.md
index 34a2afd17e..5736bbad94 100644
--- a/docs/designs/xenstore-migration.md
+++ b/docs/designs/xenstore-migration.md
@@ -147,43 +147,59 @@ the domain being migrated.
  ```
      0       1       2       3       4       5       6       7    octet
  +-------+-------+-------+-------+-------+-------+-------+-------+
-| conn-id                       | conn-type     | conn-spec
+| conn-id                       | conn-type     | flags         |
++-------------------------------+---------------+---------------+
+| conn-spec
  ...
-+-------------------------------+-------------------------------+
-| data-len                      | data
-+-------------------------------+
++---------------+---------------+-------------------------------+
+| in-data-len   | out-resp-len  | out-data-len                  |
++---------------+---------------+-------------------------------+
+| data
  ...
  ```


-| Field       | Description                                     |
-|-------------|-------------------------------------------------|
-| `conn-id`   | A non-zero number used to identify this         |
-|             | connection in subsequent connection-specific    |
-|             | records                                         |
-|             |                                                 |
-| `conn-type` | 0x0000: shared ring                             |
-|             | 0x0001: socket                                  |
-|             | 0x0002 - 0xFFFF: reserved for future use        |
-|             |                                                 |
-| `conn-spec` | See below                                       |
-|             |                                                 |
-| `data-len`  | The length (in octets) of any pending data not  |
-|             | yet written to the connection                   |
-|             |                                                 |
-| `data`      | Pending data (may be empty)                     |
+| Field          | Description                                  |
+|----------------|----------------------------------------------|
+| `conn-id`      | A non-zero number used to identify this      |
+|                | connection in subsequent connection-specific |
+|                | records                                      |
+|                |                                              |
+| `flags`        | A bit-wise OR of:                            |
+|                | 0001: read-only                              |
+|                |                                              |
+| `conn-type`    | 0x0000: shared ring                          |
+|                | 0x0001: socket                               |
+|                | 0x0002 - 0xFFFF: reserved for future use     |
+|                |                                              |

Agreed with Julien... the above two would be better swapped to match the order 
of the fields in the record.

Yes.


+| `conn-spec`    | See below                                    |
+|                |                                              |
+| `in-data-len`  | The length (in octets) of any data read      |
+|                | from the connection not yet processed        |
+|                |                                              |
+| `out-resp-len` | The length (in octets) of a partial response |
+|                | not yet written to the connection (included  |
+|                | in the following `out-data-len`)             |
+|                |                                              |
+| `out-data-len` | The length (in octets) of any pending data   |
+|                | not yet written to the connection            |

So, IIUC out-data-len is inclusive of out-resp-len?

Yes.


+|                |                                              |
+| `data`         | Pending data, first read data, then written  |
+|                | data (any of both may be empty)              |

Perhaps be more explicit here:

"Pending data: first in-data-len octets of read data, then out-data-len octets of 
written data"

Okay.



-The format of `conn-spec` is dependent upon `conn-type`.
+In case of live update the connection record for the connection via which
+the live update command was issued will contain the response for the live
+update command in the pending write data.

s/write/written for consistency I think.

I'll use "... in the pending not yet written data".


Juergen



 


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