Re: [Qemu-devel] trace: floating-point values blacklisted

["Alex Bennée" <alex.bennee@linaro.org>]

Philippe Mathieu-Daudé <philmd@redhat.com> writes:

> [I forgot to Cc the list, resending]
>
> Hi Stefan, Lluís,
>
> When trying to add a trace event to report a float value, I get:
>
> trace-events:11: Argument type 'float' is not in whitelist. Only
> standard C types and fixed size integer types should be used. struct,
> union, and other complex pointer types should be declared as 'void *'
> Traceback (most recent call last):
>   File "./scripts/tracetool.py", line 152, in <module>
>     main(sys.argv)
>   File "./scripts/tracetool.py", line 143, in main
>     events.extend(tracetool.read_events(fh, arg))
>   File "./scripts/tracetool/__init__.py", line 365, in read_events
>     event = Event.build(line)
>   File "./scripts/tracetool/__init__.py", line 283, in build
>     args = Arguments.build(groups["args"])
>   File "./scripts/tracetool/__init__.py", line 133, in build
>     validate_type(arg_type)
>   File "./scripts/tracetool/__init__.py", line 86, in validate_type
>     "declared as 'void *'" % name)
>
> Floating-point types are specified in the optional Annex F of the
> standard ("IEC 60559 floating-point arithmetic").
>
> Is there a specific reason to not trace them, or simply nobody ever had
> to trace them?

I suspect that latter. I can't see any reason not to have floats (and
doubles) in the allowed list although I wonder what happens with x86's
weird-ass 80bit values. Do floats in x86 accommodate that?

>
> Thanks,
>
> Phil.


--
Alex Bennée