On 02/06/2013 01:28 PM, Jan Kiszka wrote:
> On 2013-02-06 13:18, Gilles Chanteperdrix wrote:
>> On 02/06/2013 11:20 AM, Jan Kiszka wrote:
>>
>>> Hi Gilles,
>>>
>>> I just realized that there is now a 8253 clocksource in core-3.4+. How
>>> does this work together with Xenomai's TSC emulation via the 8254 in the
>>> x86 hal_32? Xenomai reprograms the PIT in rthal_setup_8254_tsc - is this
>>> harmless?
>>>
>>> I came across this while trying to get rid of Xenomai's "depends on
>>> !INPUT_PCSPKR" to avoid that circular Kbuild dependency.
>>
>>
>> This emulation replaces Xenomai's TSC emulation when the kernel boots on
>> a cpu without a TSC: the detection is made at run-time instead of
>> compilation time using self-modifying code (this in order to be able to
>> build Debian kernels which boots with any configuration).
>
> Hmm, that's for the kernel. But what prevents rthal_setup_8254_tsc from
> being executed in addition? I'm currently a bit lost in the #ifdefs.
rthal_setup_8254_tsc is not called.
>
>> There is no
>> reason to keep the compilation-time dependency on !INPUT_PCSPKR with
>> I-pipe core, as now the pc speaker is disabled at run-time too.
>> Unfortunately, I could not find how to arrange the Kconfig either.
>
> As this is only about practically unsupported combinations of Xenomai
> (2.6.x) and I-pipe (for kernel 2.6.x) on x86, we could move from a
> configure-time to a build-time detection (#ifdef CONFIG_INPUT_PCSPKR ->
> BUILD_BUG()).
There is already a run-time detection which simply does not declare the
PC speaker platform device when there is no tsc.
--
Gilles.
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