How to add a compile time configuration option to something in cpukit?

[Sebastian Huber]

Ralf Corsepius wrote:
> On 09/03/2009 01:41 PM, Sebastian Huber wrote:
>> Ralf Corsepius wrote:
>>   
>>> On 09/03/2009 01:35 PM, Sebastian Huber wrote:
>>>     
>>>> Ralf Corsepius wrote:
>>>>
>>>>       
>>>>> On 09/03/2009 12:18 PM, Sebastian Huber wrote:
>>>>>
>>>>>         
>>>>>> Hi,
>>>>>>
>>>>>> the FTP client resides in the cpukit.  It can use gethostbyname() to
>>>>>> obtain an
>>>>>> internet address from a DNS name.  The dependency on DNS adds 35k of
>>>>>> code
>>>>>> (THUMB op-codes).  I want to add a configuration option to disable
>>>>>> this
>>>>>> feature.  Can I add this with RTEMS_CPUOPT in cpukit/configure.ac?
>>>>>>
>>>>>>            
>>>>> As I repeatedly wrote, before: All -m* flags must be global (i.e.
>>>>> *.cfg)
>>>>>
>>>>> What you are trying to do violates the working principles of
>>>>> multilibs,
>>>>> so no way.
>>>>>
>>>>>          
>>>> Sorry now I am a little confused.  What is the connection to multilibs
>>>> if I can
>>>> enable or disable DNS support in the FTP client?
>>>>
>>>>        
>>> Here:
>>>
>>>     
>>>>    I want to add a configuration option to disable this
>>>>   feature.  Can I add this with RTEMS_CPUOPT in cpukit/configure.ac?
>>>>        
>>> "cpukit/configure.ac"
>>>
>>>
>>>      
>> So it is officially impossible to customize the cpukit via configure
>> options?
>>    
> Very oversimplified, more or less, yes.
> 
> Cpukit shares the same philosophy as "libc". Only global compile time
> options are allowed (e.g. optimization levels, enabling/disabling global
> features (.e.g. networking, profiling, ...), etc. ).
> 
> Per target/per bsp flags are not permitted, because they will be
> non-functional in multilib'ed configurations.

This is in the same category than profiling or debug support.  You can create a
cpukit that has the same functions, but one supports

open("/ftp/anonymous at www.rtems.com/robots.txt")

and the other one supports only

open("/ftp/anonymous at 67.63.146.250/robots.txt")

-- 
Sebastian Huber, embedded brains GmbH

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