On 15/08/2025 00.37, Glenn Miles wrote:
...
I have some code that tests the instructions that are
specific to the PPE42. It is a very basic test written
in assembly. This can be found at:
https://github.com/milesg-github/ppe42-tests
There is also a prebuilt image there in the images
folder.
Building the image requires a forked version of an old
version of GCC, which can be found here:
https://github.com/open-power/ppe42-gcc
Even though everything that is necessary to build the
image is publicly available, it is not a simple task.
This is why I think it would be best to just use the
prebuilt image available on github instead of trying to
build it.
With the compiler being not available in the major distros, the idea with
the prebuilt image is better indeed.
Also, there is currently no support for having console
output (this is also not supported in the actual HW).
All logging on actual hardware is done using in-memory
trace buffers that requires a special tool for translation
to a human readable format. Because of this, I'm thinking
this is not a good candidate for using the QEMU
"tests/functional" framework, which seems to rely a lot
on console output.
I do think it would be possible to use the qtest framework
to load the image and run it.
The existing test will cause a checkstop if it fails.
This leads to dumping the cpu registers, which aids in
debug. There is currently no way to tell that the
test completed, other than checking the NIP address,
but this could be easily remedied by having the guest
code write some status to a fixed memory address and
then having the qtest code poll that memory address
to determine that the test completed within some reasonable
timeout period.
The one thing that I'm not sure about with using the
qtest framework is how to retrieve the image. If anyone
has suggestions or examples of that being done for a qtest,
please do share!
The qtest framework does not have any support for downloading images. I
think you're way better off using the functional framework for this. The
console output is just optional there, so if your image does not have any
serial console output, there are still other means of checking for success.
For example, if you can be sure that a successful test always ends up with a
certain NIP, you could use
output = vm.cmd('human-monitor-command', command_line='info registers')
to check the current status of the registers and check the NIP there.
And assuming that a checkstop will cause a QMP event, you could likely also
use one of the event functions from python/qemu/machine/machine.py to check
for a failure while waiting for the right NIP.
HTH,
Thomas
