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docs: update xenstore-migration.md
Update connection record details: - make flags common for sockets and domains (makes it easier to have a C union for conn-spec) - add pending incoming data (needed for handling partially read requests when doing live update) - add partial response length (needed for proper split to individual responses after live update) Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Paul Durrant <paul@xen.org>
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Juergen Gross authored and Ian Jackson committed
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@@ -147,43 +147,60 @@ the domain being migrated.
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```
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0 1 2 3 4 5 6 7 octet
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+-------+-------+-------+-------+-------+-------+-------+-------+
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| conn-id | conn-type | conn-spec
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| conn-id | conn-type | flags |
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+-------------------------------+---------------+---------------+
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| conn-spec
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...
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+-------------------------------+-------------------------------+
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| data-len | data
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+-------------------------------+
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+---------------+---------------+-------------------------------+
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| in-data-len | out-resp-len | out-data-len |
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+---------------+---------------+-------------------------------+
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| data
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...
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```
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| Field | Description |
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|-------------|-------------------------------------------------|
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| `conn-id` | A non-zero number used to identify this |
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| | connection in subsequent connection-specific |
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| | records |
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| | |
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| `conn-type` | 0x0000: shared ring |
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| | 0x0001: socket |
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| | 0x0002 - 0xFFFF: reserved for future use |
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| | |
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| `conn-spec` | See below |
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| | |
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| `data-len` | The length (in octets) of any pending data not |
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| | yet written to the connection |
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| | |
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| `data` | Pending data (may be empty) |
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| Field | Description |
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|----------------|----------------------------------------------|
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| `conn-id` | A non-zero number used to identify this |
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| | connection in subsequent connection-specific |
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| | records |
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| | |
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| `conn-type` | 0x0000: shared ring |
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| | 0x0001: socket |
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| | 0x0002 - 0xFFFF: reserved for future use |
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| | |
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| `flags` | A bit-wise OR of: |
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| | 0001: read-only |
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| | |
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| `conn-spec` | See below |
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| | |
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| `in-data-len` | The length (in octets) of any data read |
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| | from the connection not yet processed |
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| | |
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| `out-resp-len` | The length (in octets) of a partial response |
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| | not yet written to the connection |
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| | |
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| `out-data-len` | The length (in octets) of any pending data |
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| | not yet written to the connection, including |
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| | a partial response (see `out-resp-len`) |
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| | |
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| `data` | Pending data: first in-data-len octets of |
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| | read data, then out-data-len octets of |
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| | written data (any of both may be empty) |
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The format of `conn-spec` is dependent upon `conn-type`.
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In case of live update the connection record for the connection via which
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the live update command was issued will contain the response for the live
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update command in the pending not yet written data.
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\pagebreak
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The format of `conn-spec` is dependent upon `conn-type`.
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For `shared ring` connections it is as follows:
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```
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0 1 2 3 4 5 6 7 octet
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+-------+-------+
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| flags |
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+---------------+---------------+---------------+---------------+
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| domid | tdomid | evtchn |
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+-------------------------------+-------------------------------+
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@@ -198,8 +215,6 @@ For `shared ring` connections it is as follows:
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| | it has been subject to an SET_TARGET |
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| | operation [2] or DOMID_INVALID [3] otherwise |
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| | |
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| `flags` | Must be zero |
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| | |
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| `evtchn` | The port number of the interdomain channel used |
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| | by `domid` to communicate with xenstored |
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| | |
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@@ -211,8 +226,6 @@ For `socket` connections it is as follows:
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```
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+-------+-------+
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| flags |
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+---------------+---------------+---------------+---------------+
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| socket-fd | pad |
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+-------------------------------+-------------------------------+
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@@ -221,9 +234,6 @@ For `socket` connections it is as follows:
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| Field | Description |
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|-------------|-------------------------------------------------|
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| `flags` | A bit-wise OR of: |
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| | 0001: read-only |
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| | |
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| `socket-fd` | The file descriptor of the connected socket |
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This type of connection is only relevant for live update, where the xenstored
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@@ -398,4 +408,4 @@ explanation of node permissions.
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[3] See https://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=xen/include/public/xen.h;hb=HEAD#l612
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[4] https://wiki.xen.org/wiki/XenBus
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[4] https://wiki.xen.org/wiki/XenBus
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