> Date: Sat, 31 Dec 2011 16:32:20 +0100 > From: gilles.chanteperd...@xenomai.org > To: jan0...@hotmail.de > CC: firstname.lastname@example.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? > > Another exception is the __xn_rdtsc() function, which relies on most > platforms on the same mechanism in user and kernel-space to access the > machine high resolution counter, and so has an identical implementation. > > > -- > Gilles.
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