From mboxrd@z Thu Jan  1 00:00:00 1970
From: Juergen Gross <jgross@suse.com>
Subject: Re: [PATCH v3 2/5] build: Hook the schedulers into
 Kconfig
Date: Fri, 8 Jan 2016 17:13:01 +0100
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To: Jonathan Creekmore <jonathan.creekmore@gmail.com>, Andrew Cooper <andrew.cooper3@citrix.com>
Cc: George Dunlap <george.dunlap@eu.citrix.com>, xen-devel@lists.xenproject.org, Dario Faggioli <dario.faggioli@citrix.com>
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On 08/01/16 17:02, Jonathan Creekmore wrote:
> 
> Andrew Cooper writes:
> 
>> On 08/01/16 15:47, Konrad Rzeszutek Wilk wrote:
>>> On Thu, Jan 07, 2016 at 11:29:18AM -0600, Jonathan Creekmore wrote:
>>>> Allow the schedulers to be independently enabled or disabled at
>>>> compile-time. To match existing behavior, all four schedulers are
>>>> compiled in by default, although the Credit2, RTDS, and ARINC653 are
>>>> marked EXPERIMENTAL to match their not currently supported status.
>>> By unmarking all of them in sequence I was able to get this:
>>>
>>> #
>>> # Schedulers
>>> #
>>> # CONFIG_SCHED_CREDIT is not set
>>> # CONFIG_SCHED_CREDIT2 is not set
>>> # CONFIG_SCHED_RTDS is not set
>>> # CONFIG_SCHED_ARINC653 is not set
>>> # CONFIG_SCHED_CREDIT_DEFAULT is not set
>>> # CONFIG_SCHED_CREDIT2_DEFAULT is not set
>>> # CONFIG_SCHED_RTDS_DEFAULT is not set
>>> # CONFIG_SCHED_ARINC653_DEFAULT is not set
>>> CONFIG_SCHED_DEFAULT="credit"
>>>
>>>
>>> And the hypervisor did build with:
>>>
>>> [konrad@char xen]$ nm --defined xen-syms |grep schedulers
>>> ffff82d080290d58 D __end_schedulers_array
>>> ffff82d080290d58 D __start_schedulers_array
>>>
>>> :-)
>>>
>>> Not exactly sure if there is some way to make us _not_ shoot
>>> ourselves in the foot by mistake.
>>>
>>> Perhaps the build should complain if the size of the
>>> __schedulers_array is zero?
>>
>> Hmm yes - an ASSERT() at the bottom of the linker file would be a very
>> good defensive measure.
>>
>> A hypervisor without any schedulers compiled in will be rather sad.
> 
> I can definitely add that in.

I think there should be an ASSERT (or some other measure) to
ensure the default scheduler is available.


Juergen