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Date: Sun, 01 Jan 2012 21:54:21 +0100
From: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
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Subject: Re: [Xenomai-core] user and kernel space
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To: Jan-Erik Lange <jan0385@domain.hid>
Cc: xenomai@xenomai.org

On 01/01/2012 01:56 PM, Jan-Erik Lange wrote:
> 
> 
> 
> 
>> Date: Sat, 31 Dec 2011 16:32:20 +0100 From:
>> gilles.chanteperdrix@xenomai.org To: jan0385@domain.hid CC:
>> xenomai@xenomai.org Subject: Re: [Xenomai-core] user and kernel
>> space
>> 
>> On 12/31/2011 12:18 PM, Jan-Erik Lange wrote:
>>> 
>>> Hello,
>>> 
>>> I have a question concerning user space and kernel space. I'm
>>> dealing with the native API and I read, that this API provides
>>> the same funtkions for both kernel and user space.
>>> 
>>> When looking at the sourcecode of buffer.h for example, there I
>>> find a section called public interface. When looking at the
>>> function rt_buffer_create(); for example, how does the
>>> Implementation von this function in userspace differs to the
>>> implementation for this function kernel space? Or is it the same
>>> implementation for user and kernel space.
>> 
>> For most services such as buffer services, user functions emit
>> system calls which implementation in kernel-space use the
>> corresponding kernel service.
>> 
>> There are some exceptions such as mutexes implementation where we
>> try hard to avoid system calls and so provide both a user-space 
>> implementation and a kernel-space implementation.
> 
> 
> Ok, but the names of the API function are the same for user and
> kernel space. How is it realized to take the implementation A for
> kernel space and the implementation B for userspace? Is this realzied
> in the linking process?

Yes, kernel and user-space are separated execution space, there is no
possible confusion.

-- 
                                                                Gilles.