[Buildroot] [PATCH 1/1] xenomai: Add choice for Cobalt/Mercury core

Arnout Vandecappelle arnout at mind.be
Sat Apr 8 14:22:28 UTC 2017



On 08-04-17 15:34, Thomas Petazzoni wrote:
> Hello,
> 
> On Fri,  7 Apr 2017 01:41:39 +0200, Pawel Sikora wrote:
> 
>> +choice
>> +	prompt "Xenomai core"
>> +	default BR2_PACKAGE_XENOMAI_MERCURY
>> +	help
>> +	  Manually select the Xenomai core. Default option depends if
>> +	  you selected BR2_LINUX_KERNEL_EXT_XENOMAI.
>> +	  If yes, then default option will be Cobalt.
>> +	  Otherwise you can use just the Mercury core with the
>> +	  native Linux kernel.
>> +
>> +config BR2_PACKAGE_XENOMAI_MERCURY
>> +	bool "Mercury"
>> +	depends on !BR2_LINUX_KERNEL_EXT_XENOMAI
>> +	help
>> +	  Select Mercury core for the Xenomai userspace.
>> +	  If you want Cobalt core, you need to enable
>> +	  BR2_LINUX_KERNEL_EXT_XENOMAI in the Linux Kernel ->
>> +	  Linux Kernel Extensions menu.
>> +
>> +config BR2_PACKAGE_XENOMAI_COBALT
>> +	bool "Cobalt"
>> +	depends on BR2_LINUX_KERNEL_EXT_XENOMAI
>> +	help
>> +	  Select Cobalt core for the Xenomai userspace.
>> +	  If you want Mercury core, you need to disable
>> +	  BR2_LINUX_KERNEL_EXT_XENOMAI in the Linux Kernel ->
>> +	  Linux Kernel Extensions menu.
> 
> Does it really make sense to have a "choice" when in fact it's
> impossible to have both options of the choice visible at the same time?
> One option depends on !BR2_LINUX_KERNEL_EXT_XENOMAI and the other
> option depends on BR2_LINUX_KERNEL_EXT_XENOMAI.
> 
> I'm not sure how to handle this. Do we automatically switch between
> Cobalt and Mercury depending on whether the Xenomai kernel extension is
> enabled?
> 
> Do we use Mercury by default, and offer a sub-option to explicitly
> enable Cobalt when the Linux kernel extension is available?

 The mercury option certainly only makes sense when the Xenomai extension in the
kernel is NOT selected, so that can be kept.

 However, the cobalt option still makes sense if the Xenomai extension is not
selected. For starters, it's possible that the kernel is built outside of
Buildroot. But also it's possible that we use a custom kernel that is already
Xenomai-patched, in which case the Xenomai extension is not used.

 So just remove the dependency from cobalt.

 I think indeed it does make sense to use Mercury by default, except when the
Xenomai extension is selected.

 Regards,
 Arnout

-- 
Arnout Vandecappelle                          arnout at mind be
Senior Embedded Software Architect            +32-16-286500
Essensium/Mind                                http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium           BE 872 984 063 RPR Leuven
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