Re: [Qemu-devel] [PATCH RFC] ps2: set the keybord output buffer size as the same as kernel

[Juan Quintela]

"Gonglei (Arei)" <address@hidden> wrote:
>> 
>> Hi, Gerd and Juan.
>> 
>> Thanks for your guides about the confuse live migration about changing the
>> keyboard buffer size.
>> According your suggestion, I got two solutions to address the issue:
>> 
>> - Keep the data array 256 bytes long, change the rptr/wptr/count/data array 
>> at
>> post_load(), both
>>  Ps/2 keyboard and mouse. This solution can be compatible with older qemu
>> versions, which can
>>  do live migration each other.
>> 
>> -Change the data array to 16 bytes, still save as PS2_QUEUE_SIZE. Reset the
>> rptr/wptr/count at
>> post_load(), both ps/2 keyboard and mouse. Add VMSTATE_UNUSED(256-16) in
>> struct vmstate_ps2_common.
>> This solution just save the 16 bytes buffer and drop the rest, So we can't
>> migrate vm to older qemu versions.
>> But migration from old qemu to new qemu is ok.
>> 
> Sorry, the second solution also support cross-version live migration each 
> other.

Second solution is better in the sense that it allows forward and
backward migration.   The first one only allows forward migration.

Please use second one.

Later, Juan.

>
>> I have tested the two solutions, but which one is better? Expect your reply.
>> Thanks!
>> 
>
> Best regards,
> -Gonglei