Re: [Xen-devel] [PATCH v2 01/10] hvm/hpet: Add manual unit test code.

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 11.04.14 at 04:53, <dslutz@xxxxxxxxxxx> wrote:
> This is because "make test" gives me:

I don't think you need to be worried about this failing - just make sure
"make -C .../tools/tests/hpet" works, and ideally (again just like the
x86 emulator one) also have a "run" target in the Makefile.

> During my looking for what was happening, I added debug code
> that would allow me to force "diff" to selected values.  This was
> how I found out that "-diff > HPET_TINY_TIME_SPAN" would cause
> linux to report this and crash.  On closer looking into this, I was
> able to determine that the use extInt path would also fail even if I
> got xen to provide this interrupt.  The reason being that
> 
>   (uint32_t)(-HPET_TINY_TIME_SPAN-1)
> 
> Sets the  "delta" (ns) to more then 60 seconds in the future.  And
> the timer test happens in the 1st 5 seconds of a linux boot on my
> test server.
> 
> So I send out the v1 patch.
> 
> Later I found out that any value that is > ~3 seconds would also
> cause a linux crash even if xen is changed to provide extInt
> interrupts.

But Linux expectations shouldn't matter in this discussion at all,
except for verifying that changes don't break things. I.e. any
change you propose should be explained comparing with real
hardware behavior, not with what Linux (or Windows, or ...)
expect. OS expectation should become a reason for a change only
if there is something that we absolutely can't make behave
hardware like.

Jan


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