Re: [Qemu-devel] [RFC PATCH 0/5] FAULT INJECTION FRAMEWORK

[Philippe Mathieu-Daudé]

On 7/1/19 10:37 AM, Stefan Hajnoczi wrote:
> On Fri, Jun 28, 2019 at 02:45:29PM +0200, Damien Hedde wrote:
>> This series adds a python framework aiming to provide some ways to do fault
>> injection in a running vm. In its current state, it allows to easily interact
>> with memory, change gpios and qom properties.
>>
>> The framework consists in a python script based on the qmp existing module
>> which allows to interact with the vm.
> 
> How does this compare to qtest?  There seems to be a lot of overlap
> between them.
> 
> Why is it called "fault injection"?  The commands seem to be
> general-purpose device testing functions (like qtest and libqos), not
> functions for testing error code paths as would be expected from a fault
> injection framework.

I understand qtest is to test QEMU, while this framework/command is to
test how the guest react to an hardware faults.

To use the qtest_mem commands you need to run QEMU with the qtest
chardev backend, while this series expose a QMP interface.

To avoid the overlap, a cleaner follow up might be to have qtest wrap
these QMP commands (mostly like HMP commands do).

Another note while looking at a glance, qtest uses the 1st cpu address
space view, this series allow to select a specific cpu.

It makes sense to me to be able to select address spaces by name (more
generic, not restricted to a cpu view, since one might want to inject
fault in a device ram not always mapped to a cpu: dma, emac desc).

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