Re: [Qemu-devel] [PATCH] optionally specify vm stop message

[Anthony Liguori <anthony@codemonkey.ws>]

Gleb Natapov wrote:
> On Thu, Jan 15, 2009 at 02:46:06PM -0600, Anthony Liguori wrote:
>   
>> Gleb Natapov wrote:
>>     
>>> Should be applied on top of ENOSPC series.
>>>   
>>>       
>> How about just adding a new vm_stop reason?  That will work out better  
>> when we introduce the improved monitor.
>>
>>     
> We may want to specify different message for the same reason. For
> instance we may want to print the name of the file we failed to write
> to.

I'm thinking about this from a management tool perspective.  When we 
have a better monitor interface, this would generate an async 
notification.  Instead of generating an arbitrary string, it could send 
a reason code that has a well defined meaning.

For now, within vm_stop, it can say if (reason == VM_STOP_ENOSPC) 
printf("ran out of space"); or something.

There are other places we stop a vm, like when -no-shutdown is used, 
where using a reason code would be very useful.

>  Also non zero reasons a handled differently by vm_stop. Don't know
> why.
>   

It's an ugly hack for gdbstub.  It notifies gdb when a breakpoint 
occurs.  We have far too many state tracking mechanisms.  Anyway, gdb 
can pass something like VM_STOP_BP and that can be used to trigger the 
callback.

Regards,

Anthony Liguori

> --
> 			Gleb.
>
>
>