llvm dev - Dec 2014 - [LLVMdev] Newbee question: LLVM backend regression tests for thumb1 targets on simulator possible?

On 18 December 2014 at 04:02, Tim Northover <t.p.northover at gmail.com>
wrote:
>> You have some special version of qemu? My default distribution's
qemu
>> package did not have a cortex-M0 nor has qemu head freshly taken from
git:
>
> The trouble with Cortex-M0 (from a virtualised testing perspective) is
> that it doesn't have an MMU, so any "real" operating system
> environment will be far more artificial than we'd like, and probably
> very low down on qemu's list of priorities to boot.
>
> Testing a Thumb1 CPU with an MMU (I'm sure there are ARM11* CPUs with
> MMU but before Thumb2, but would need to dig into which is closest to
> v6m) would cover *most* issues, but obviously not the ways in which
> Cortex-M0 is closer to v7 than v6.
Why not test on real hardware?

https://developer.mbed.org/platforms/DipCortex-M0/

cheers,
--renato

On 19 December 2014 at 10:29, Bjoern Haase <bjoern.m.haase at web.de>
wrote:
> In my opinion there is more need for a regression test framework in a
> simulation environment in a first step. Of course an optional, second step
> with tests on real-world HW would not hurt. Actually qemu does not seem to
> be this bad for this purpose.
I get what you mean, and I agree with you. Testing "if it should work"
is one thing, and testing "if it actually works" is another. Plus the
difficulties of testing in real hardware that I know only too well.

Though, trying to create a simulated environment that will be relevant
for the system you care about might be as complicated as real hardware
tests, and it will never give you the guarantee that you're not
missing the point.

I would run Thumb1 tests on any Thumb1 emulator (no need to make it
look like an M0) and reduce the set of tests on a real M0 for the
things that you can actually test, and do it.

cheers,
--renato