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Diffstat (limited to 'Documentation/mbox_protocol.md')
-rw-r--r-- | Documentation/mbox_protocol.md | 21 |
1 files changed, 11 insertions, 10 deletions
diff --git a/Documentation/mbox_protocol.md b/Documentation/mbox_protocol.md index 5a0879e..70728e9 100644 --- a/Documentation/mbox_protocol.md +++ b/Documentation/mbox_protocol.md @@ -210,16 +210,17 @@ Given that a majority of command and response arguments are specified as a multiple of block size it is necessary for the host and BMC to agree on a protocol version as this determines the block size. In V1 it is hard coded at 4K and in V2 the BMC chooses and specifies this to the host as a response -argument to MBOX_GET_INFO. Thus the host must always call MBOX_GET_INFO before -any other command which specifies an argument in block size. - -The host must tell the BMC the highest protocol level which it supports. The -BMC will then respond with a protocol level. If the host doesn't understand -the protocol level specified by the BMC then it must not continue to -communicate with the BMC. Otherwise the protocol level specified by the -BMC is taken to be the protocol level used for further communication and can -only be changed by another call to MBOX_GET_INFO. The BMC should use the -request from the host to influence its protocol version choice. +argument to `MBOX_GET_INFO`. Thus the host must always call `MBOX_GET_INFO` +before any other command which specifies an argument in block size. + +When invoking `MBOX_GET_INFO` the host must provide the BMC its highest +supported version of the protocol. The BMC must respond with a protocol version +less than or equal to that requested by the host, or in the event that there is +no such value, an error code. In the event that an error is returned the host +must not continue to communicate with the BMC. Otherwise, the protocol version +returned by the BMC is the agreed protocol version for all further +communication. The host may at a future point request a change in protocol +version by issuing a subsequent `MBOX_GET_INFO` command. ### Window Management |