Re: Using signals to communicate two Qemu processes

[Anthony Liguori <anthony@codemonkey.ws>]

Dor Laor wrote:
> Passera, Pablo R wrote:
>> Hi all,
>>         I am trying to communicate two VMs using a virtio driver. 
>> Once a data is moved to the driver I want to notify the other Qemu 
>> process that there is new data available in the buffer. I was 
>> thinking about using linux signals to synchronize both processes but 
>> when I register my SIGUSR1 handler in Qemu I am seeing an strange 
>> behavior. After starting the VM and Linux gets loaded, Qemu is 
>> receiving SIGUSR2 at a regular time period. Looking a little bit at 
>> the code I realize that signals are being used for other purposes in 
>> Qemu, however, SIGUSR1 is not used. Is it possible to use signals to 
>> synchronize these processes or should I think about using a different 
>> mechanism?
>>
>>   
> SIGUSR2 is used as aio completion signal. You can use SIGUSR1 but you 
> need to know what you're doing (some threads block signals).
> Better fit would be a pipe.

Or even a unix domain socket.

Regards,

Anthony Liguori