[Qemu-devel] Re: [uq/master patch 2/5] kvm: add logging count to slots

[Jan Kiszka]

Avi Kivity wrote:
> On 04/24/2010 10:34 AM, Jan Kiszka wrote:
>> Marcelo Tosatti wrote:
>>   
>>> Otherwise there is no way to differentiate between global and slot
>>> specific logging, so for example
>>>
>>> vga dirty log start
>>> migration start
>>> migration fail
>>>
>>> Disables dirty logging for the vga slot.
>>>      
>> This is not true (unless there is a bug): Migration logging is tracked
>> via KVMState::migration_log and vga logging via KVMSlot::flags. Both are
>> merged in kvm_set_user_memory_region. Thus no such change is required
>> for upstream.
>>    
> 
> It's still a good idea.  The current API assumes that there will be only
> one slot-based client (or that multiple clients will keep the refcount
> themselves).
> 
> After the bytemap -> multiple bitmaps conversion this can be extended to
> each client getting its own bitmap (and therefore, s/refcount/list of
> bitmaps/ and s/!refcount/list_empty()/).
> 

No concerns if
 - there is an existing use case for multiple clients, at least in
   qemu-kvm
 - the logging API is consistently converted, not just extended
   (IOW, migration_log is converted to logging_count)
 - someone signs he checked that current use of start/stop in qemu is
   completely symmetrical (I think to remember this used to be not the
   case, but I might be wrong)

Jan

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