[Xenomai-help] Re: [Xenomai-core] possible future conflict w LOCAL_APIC

[Jan Kiszka <jan.kiszka@domain.hid>]

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Jan Rüdiger wrote:
> Jan Kiszka wrote:
>> Jan Rüdiger wrote:
>>> Hello
>>>
>>> Few months ago there was a discussion about disabling local apic in the
>>> kernel. The last point in this discussion was:
>>>
>>>> update:
>>>>
>>>> Ingo Molnar has voiced strong preference that the config option remain,
>>>> citing 60kb growth in its removal.  So its probably safe for now ;-)
>>> Now i have the problem that i cant disable the X86_UP_APIC anymore when
>>> building the kernel 2.6.19. Normally this isn't a problem since it is
>> ???
>>
>> There is no "select X86_UP_APIC" in kbuild that would make this mandatory.
> 
> Thanks for your fast reply. Actually the option X86_UP_APIC is missing
> when doing "make menuconfig" under "Processor type and Feature" and also
> in the .config file. Thats why i can't disable it.
> As far as i understood it, this option was taken away an replaced with
> the possibility to have noapic flag at boot time.
> With this, however, xenomai ist still build with APIC enabled and
> refuses to run.

Do you happen to have SMP on? It takes away the choice of UP_APIC,
because it assumes to find an APIC in any case.

> 
> My 2.6.19.2 kernel was downloaded from kernel.org. All i did was "make
> cloneconfig" and then enabling xenomai and a few other things
> (preemption etc.)

Unless you need it otherwise, CONFIG_PREEMPT is not required for good
Xenomai latencies.

Jan


PS: Please take care of CC, I re-added xenomai-help.


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