[Xenomai-help] atomic_t in userspace

[Xenomai-help] atomic_t in userspace

[Steven Seeger]

I just upgraded to the latest SVN after a few months of hiatus, and my
userspace app that used atomic_t through nucleus/asm/atomic.h no longer
works. It says it can't find atomic_t, and it seems that all the atomic
operations have been put inside a kernel only #if. Is there another way to
use atomics in my shadowed threads from userspace? Is there any equivalent?

Steven

Re: [Xenomai-help] atomic_t in userspace

[Philippe Gerum]

Steven Seeger wrote:
> I just upgraded to the latest SVN after a few months of hiatus, and my
> userspace app that used atomic_t through nucleus/asm/atomic.h no longer
> works. It says it can't find atomic_t, and it seems that all the atomic
> operations have been put inside a kernel only #if. Is there another way to
> use atomics in my shadowed threads from userspace? Is there any equivalent?
> 

Atomic ops were formerly obtained by including linux/include/asm/atomic.h, and 
doing so from user-space context caused a number of troubles, notably to C++ 
users. Additionally, doing so was clearly bad practice since we would cause 
namespace pollution and all sort of conflicts with kernel-only symbols. For this 
reason, it has been decided to (re-)implement the very few atomic ops we need in 
the user-space section of xenomai/include/asm-*/atomic.h, instead of reading them 
from the kernel file(s). But since atomic counters are not needed (anymore) by 
Xenomai's user-space code, they have not been provided.

You should implement your local copy of the missing stuff, or directly include 
linux/include/asm/atomic.h from your own headers, but at your own risk.

> Steven
> 
> 
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-- 

Philippe.