Re: [Qemu-ppc] [PATCH] PPC: Fix via-cuda memory registration

[Alexander Graf]

Am 11.09.2011 um 12:41 schrieb Avi Kivity <address@hidden>:

> On 09/08/2011 07:54 PM, Alexander Graf wrote:
>> PS: Please test your patches. This one could have been found with an 
>> invocation
>>     as simple as "qemu-system-ppc". We boot into the OpenBIOS prompt by 
>> default,
>>     so you wouldn't even have required a guest image or kernel.
>> 
> 
> 
> Sorry about that.
> 
> Note that it's pretty hard to test these patches.  I often don't even know 
> which binary as the device->target relationship is not immediately visible, 

The patch was explicitly to convert ppc ;).

> and I don't really know what to expect from the guest.

The very easy check-fundamentals thing to do for ppc is to execute 
qemu-system-ppc without arguments. It should drop you into an OF prompt. Both 
memory api bugs on ppc I've seen now would have been exposed with that.

I agree that we should have something slightly more sophisticated, but doing 
such a bare minimum test is almost for free to the tester and covers at least 
basic functionality :). I don't mind people introducibg subtle bugs in corner 
cases - these things happen. But an abort() when you execute the binary? That 
really shouldn't happen ever. This one is almost as bad.

> It would be best if we had a kvm-autotest testset for tcg, it would probably 
> run in just a few minutes and increase confidence in these patches.

Yeah, I am using kvm-autotest today for regression testing, but it's very hard 
to tell it to run multiple different binaries. The target program variable can 
only be set for an execution job, making it impossible to run multiple targets 
in one autotest run.

Also, not all targets implement enough functionality for autotest. The e500 
machine for example doesn't support power off - real hw doesn't either. So we 
always have to kill the vm exposing potential data loss. But that's probably 
gone by now with cache=unsafe fixed with your previous patches :). However that 
means that a simple test run takes quite a while already thanks to timeouts.


Alex