[Buildroot] [PATCH v3 3/4] support/testing: test can use the locally generated qemu host tool

[Etienne Carriere <etienne.carriere@linaro.org>]

Hello Ricardo,
Hello Thomas,

Thanks for your feedback and sorry for this late answers.

On Tue, 2 Apr 2019 at 09:06, Thomas Petazzoni
<thomas.petazzoni@bootlin.com> wrote:
>
> Hello Ricardo and Etienne,
>
> On Sat, 30 Mar 2019 00:30:01 -0300
> Ricardo Martincoski <ricardo.martincoski@gmail.com> wrote:
>
> > I am not strongly against it.
> > But let me ask:
> > Are you or someone else having trouble with any other test case when using
> > "old" qemu versions from host?
> >
> > If the answer is no, maybe we should keep things simple and use a patch very
> > similar to v2 of this one, just adding the host-qemu to the test case config
> > fragment and the 'local' argument to Emulator.run.
> > I say similar to v2 because I think your implementation in v3 with the
> > 'qemu_bin' variable is better than v2.

Up to my knowledge, when running qemu-system-arm without secure world
emulation, old Qemu versions are fine (I.e. v2.x).
But when emulating arm w/ trustzone (qemu-system-arm -machine
secure=on ...), one must use at least Qemu v2.10, and recommended
version is v3.1.
- v2.10 is necessary, because of commit b29fd33db578 ("target/arm: use
DISAS_EXIT for eret handling") that is mandated.
- v3.1 is recommended since commit fb23d693a3e0 ("hw/arm/virt: add DT
property /secure-chosen/stdout-path indicating secure UART"). Without
this fix, secure/non-secure world consoles are mixed resulting in
weird traces (unless one fully disables secure world runtime traces).

>
> I totally agree here. Having this option --local-emulator doesn't make
> much sense. We would have to use it for some tests, but not for some
> other tests.
>
> Instead, we want each test to know whether it needs a recent enough
> version of Qemu, or whether the system-provided Qemu version is good
> enough.

Fair enough.

>
> > Another approach "to have an generic option to script run-tests to build the
> > emulator within the test config" (quoting your reply to v2) would be:
> > Instead of adding a command line argument to run-tests, create a new flag in
> > the test case class, perhaps named "build_emulator". If that flag is True, the
> > host-qemu is automatically added to the config fragment by the test infra. The
> > same flag could be propagated to the Emulator.init so we don't need to pass
> > 'local' to Emulator.run.

Ok, I think I see your idea.
I'll come up with a v4 for this whole patch series.

Thanks again
etienne

>
> Yes, something like that sounds good.
>
> Best regards,
>
> Thomas
> --
> Thomas Petazzoni, CTO, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com